Feasibility Study For A Wvo Radiant Heat System In Allegheny`s

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Allegheny College Allegheny College DSpace Repository http://dspace.allegheny.edu Projects by Department or Interdivisional Program Academic Year 2016-2017 2017-04-03 Feasibility Study for a WVO Radiant Heat System In Allegheny’s Greenhouse Gould, Bennett http://hdl.handle.net/10456/42791 All materials in the Allegheny College DSpace Repository are subject to college policies and Title 17 of the U.S. Code. Feasibility Study for a WVO Radiant Heat System In Allegheny’s Greenhouse By Bennett Gould Department of Environmental Science Allegheny College Meadville, Pennsylvania April 2017 Table of Contents: Acknowledgements: iii Abstract: iv Introduction: 1 Preliminary Design Considerations: 5 Heat Distribution: 5 Boiler Intake and Ventilation: 7 Methods: 9 Modeling Heating and Fuel Demand: 9 Fuel Availability: 16 Boiler Selection: 16 Component Selection and Pricing: 17 Results: 18 Heating and Fuel Demand: 18 Fuel Availability: 19 Boiler Selection: 20 Component Selection and Pricing: 21 Discussion: 22 Heating and Fuel Demand: 22 Fuel Availability: 22 Boiler Selection: 22 Component Selection and Pricing: 23 • Heating Elements/Piping • Included Equipment • Manifold/Header • Venting Next Steps 25 Works Cited: 26 ii Acknowledgements: My friends and family: For believing in my ideas and all the generous support. Kelly Boulton: For four wonderful years working together, willingness to lend an ear, and all you do for the Allegheny Community. Professor Ian Carbone: For guiding me through the Comp process and always having great new ideas. Kerstin Martin: For your insights on winter growing and greenhouse design. Professor Eric Pallant: For planting the idea that eventually developed into this Comp. Professor Rich Bowden: For being my Advisor and, more importantly, my “Mountain Father.” Constellation’s E2 Energy to Educate Grant Program: For providing the financial backing that will take this project from concept to reality. iii Name: Bennett Gould Major: Environmental Science Thesis Committee: Ian Carbone, Kelly Boulton Title: Date: Spring, 2017 Feasibility Study for a WVO Radiant Heat System in Allegheny’s Greenhouse This comprehensive thesis serves to examine the feasibility, design, and cost of a waste vegetable oil (WVO) fueled hydronic heating system for the proposed greenhouse in Allegheny College’s Carr Hall garden. By utilizing waste products as a fuel source, the proposed system will be carbon neutral while maintaining high efficiency and extending the growing season on either end of Meadville’s winter. Virtual Grower software was utilized to perform calculations for greenhouse heating demand and fuel consumption, while data from campus dining halls indicated WVO fuel availability on campus. From this data, numerous waste oil boilers for hydronic heat systems were examined for suitability to the greenhouse’s requirements. Results indicate that Allegheny College has ample fuel available to heat the greenhouse with WVO and a boiler and heat distribution system that meets the heating demand, budgetary allowances, and design requirements of the greenhouse is entirely feasible. As such, this thesis is able to select and recommend a boiler and components needed to implement a WVO fueled hydronic heating system in the Carr Hall Garden Greenhouse. iv Introduction: In February 2013, Allegheny College broke ground on a 3,000 square foot garden located next to Carr Hall. The “Carrden” serves as a hands-on educational tool for the student body and greater Meadville community while sustainably providing fresh, local, organic food to the campus dining halls. In return, the dining halls collect and compost their food scraps, sending nutrient-rich soils back to the Carrden for fertilization of the growing beds. (Allegheny College, 2017) The Carrden is one of many community gardens in Meadville, PA that host a growing network of individuals interested in small-scale agriculture, healthier eating, community food access, and locally-sourced produce. While there has been increasing emphasis on sustainable production of local foods, off-season growing remains a major hurdle in terms of energy intensity and efficiency for northern regions that rely on greenhouses for winter growing. (Carbone, Boulton, & Pallant, 2016) To address this challenge, Allegheny College will be constructing a small-scale demonstration greenhouse in the Carrden, utilizing funding from the Constellation Energy to Educate Grant Program to develop greenhouse heat and power systems that make use of recoverable or otherwise wasted sources of energy. (Stockwell, 2016) This greenhouse will serve as a model for application of new technologies elsewhere and an educational tool for hundreds of students in the surrounding communities. (Allegheny News and Events, 2017; Belson, 2017; Carbone et al., 2016) Professor Ian Carbone envisions the greenhouse as a “useful educational tool [where] students can learn about season extension when growing food…optics and how some solar technologies work… energy efficient building design, and also… waste energy and biofuels.” (Belson, 2017) For power generation, the roof will be built with integrated Luminescent Solar Concentrators (LSCs), which are “a novel photovoltaic technology that can generate electricity from ‘wasted’ light… allowing photosynthetically active light to reach the plants below while converting unusable wavelengths into electricity.” (Carbone et al., 2016) Further, this facility will serve as a spotlight for student-designed systems, adaptive reuse of building materials, rainwater capture, high-efficiency building envelopes, and energy usage monitoring systems. (Allegheny News and Events, 2017; Belson, 2017) While the superstructure, floor plan, and solar power system have already been designed, there remains a need for design of a greenhouse heating system that can efficiently and economically maximize the growing season through Meadville’s cold winter months, while mitigating environmental impact and carbon footprint of the operation through renewable energy sources. Traditionally-heated greenhouses often utilize fossil fuels, such as natural gas, heating oil, gasoline, diesel, or fossil fuel-derived electricity as the means of powering boiler/hydronic or forced air heating systems. However, these traditional energy sources are nonrenewable and produce significant greenhouse gas emissions that contribute to global climate change. Allegheny College has examined a number of alternative energy sources for the greenhouse heat needs, most notably including feasibility studies for a geothermal/geoexchange well 1 system and on-campus wind turbine electricity generation. Ultimately, attention turned to the large supply of used fryer oil produced on campus by Parkhurst Dining Services. Though presently being sent to a regional biodiesel producer, this supply of free waste vegetable oil (WVO) presents an inviting fuel source for a greenhouse heating system. WVO, also known as Used Cooking Oil (UCO) or Triglyceride Burner Fuel (TBF), is preferable to fossil fuel energy sources and even other renewables, such as biodiesel, for a number of reasons. (Turner & Turner, 2016) For starters, WVO is a renewable, plant-derived fuel source with potential for full carbon emission neutrality when the utilized WVO would otherwise become landfilled waste if not diverted into fuel use. (Leue, 2002; Leue & Horowitz, n.d.; Shepley, 2010; Turner & Turner, 2016) Compared to fossil fuels, WVO requires significantly less refining and processing, does not have to be drilled and extracted, and has far less polluting exhaust emissions during combustion in terms of greenhouse gas levels, acid/sulfur, unburned hydrocarbons, soot, and carbon monoxide. (Leue, 2002; Leue & Horowitz, n.d.) These benefits can be attributed to WVO’s beginnings as a non-toxic, biodegradable, food-grade product that is regularly consumed by humans. (Leue & Horowitz, n.d.) Even compared to biodiesel, WVO has a number of benefits including less processing time, resources, and space needed to clean/refine the fuel; no need for toxic chemicals used in the biodiesel production process; and fewer waste products (just some leftover food bits and water) that are compostable and pose no hazardous waste restrictions. (Leue & Horowitz, n.d.; Pahl, 2007; Turner & Turner, 2016) Economically speaking, use of WVO as a fuel source is a viable option. There are a number of farms around the country that are already using WVO to heat greenhouses through a variety of systems. (Collins, 2009; Grubinger, 2008; Harper & Grubinger, 2008; Pahl, 2007; Shepley, 2010; Turner & Turner, 2016) Given that WVO is generally very low cost (or even free) relative to fossil fuel oils, the economic benefits of using a cheap fuel source outweigh higher upfront installation costs of a WVO burner vs. a conventional oil burner, even when factoring in higher maintenance labor costs in a WVO system. (Collins, 2009; Grubinger, 2008; Shepley, 2010) It is possible to design a home-fabricated burner (Addison, 2005) or to purchase a WVO specific burner assembly. (Leue, 2002; Leue & Horowitz, n.d.) However, in the vast majority of WVO heated greenhouses, farmers are using off the shelf “waste oil” heaters from a variety of manufacturers with little to no modification. (Collins, 2009; Grubinger, 2008; Harper & Grubinger, 2008; Pahl, 2007; Shepley, 2010; Turner & Turner, 2016) Waste oil heaters are designed to burn a number of fossil-fuel based waste oil products including motor oil, hydraulic fluid, transmission fluid, #2 heating oil, etc. and are being used in both forced air heating systems and hydronic heating systems. (Clean Burn, 2016; Collins, 2009; Grubinger, 2008; Harper & Grubinger, 2008; Pahl, 2007; Shepley, 2010; Turner & Turner, 2016) In a forced air system, a burner heats air that is then moved through a building using ductwork 2 and a blower. Hydronic heating, also commonly referred to as radiant heating, involves a heater that warms water or some other liquid medium that is then circulated through piping to heat exchangers such as radiators, baseboard heaters, or in-surface piping in a space that is to be heated. Once at the radiator, heat is released into the general area via electromagnetic radiation (hence radiant heat). (Bradford White Corporation, 2016; EWEB, n.d.; Hydronic Heating, 2016a, 2016c; Olesen, 2002; PB Heat, LLC., 2013) This type of hydronic heating system in its basic parts involves a water boiler, fluid pump, pipe work to and from heat exchangers, and a thermostatic control. (Bartok & Grubinger, 2012; Hydronic Heating, 2016c) Forced air and hydronic heating systems both have distinct pros and cons, but ultimately hydronic heating seems a more logical choice for the Carrden Greenhouse. Hydronic heating gets an immediate advantage over forced air as water and other fluids are better conductors of heat than air, giving hydronic systems higher efficiency. (Black Diamond Plumbing & Mechanical, Inc., 2013; Franco, 2017; Hydronic Heating, 2016a, 2016d; KompareIt, 2017; Olesen, 2002) Efficiency is also increased in hydronic systems by use of closed loop system piping that retains any unused heat, recirculating the still warm water back through the system. (Franco, 2017) This literally watertight sealed setup also has the thermal benefit of no leaking heat as often occurs in unsealed forced air ductwork. (Hydronic Heating, 2016b) Further, forced air systems create a pressure gradient between the inside and outside of a structure, leading to either heated air wastefully being pushed out of the structure or colder outside air being drawn into the structure, creating drafts. Hydronic heating does not circulate air, thus avoiding draft issues. (Bradford White Corporation, 2016; Hydronic Heating, 2016d; Olesen, 2002) With all of these efficiency advantages over forced air, the higher upfront cost of a hydronic heat system over forced air can be offset by lower operating costs in the long term. (Black Diamond Plumbing & Mechanical, Inc., 2013; Hydronic Heating, 2016b; KompareIt, 2017) Related to airflow are a number of other problems with forced air that radiant heat systems mitigate. When a forced air system heats and blows air, the air tends to lose moisture content, creating imbalanced humidity. (Hydronic Heating, 2016d) While this can be corrected in a forced air system with the introduction of a humidifier, hydronic heating avoids the issue altogether by not heating the air directly or moving it around, leading to more balanced, natural levels of humidity within a structure. Of particular concern in a greenhouse is the issue of air movement’s impact on transpiration of water out of plants. As the amount of airflow passing over a plant increases, the rate of transpiration increases while pockets of otherwise humid air directly surrounding the plant created by transpiration are blown away, being replaced by drier air. (USGS, 2016) This means that plants in a high airflow environment will lose, and therefore require, more water than plants in a more stationary air environment such as those created in a hydronic heating system. In a radiant heat system, limited air movement also means lower levels of 3 suspended airborne particulates, allergens, and mites than are found in forced air systems, leading to positive respiratory health benefits. (Hydronic Heating, 2016d; Olesen, 2002; PB Heat, LLC., 2013) Lack of an air blower (excluding potential blower used within a boiler’s combustion processes) in a hyrdonic heat system also leads to generally quieter operation than the forced air alternative. (Bradford White Corporation, 2016; Olesen, 2002; PB Heat, LLC., 2013) Hydronic heating systems can also be designed to work with multiple pipe circuits, creating capacity to have independent temperature-controlled zones. (Bradford White Corporation, 2016; EWEB, n.d.; Olesen, 2002) With forced air, the furnace generally produces one temperature of air for the entire structure while individual room/zone temperatures are controlled by airflow dampers, limiting temperature customization options across rooms/zones. Beyond individually controlled temperature zones/circuits, hydronic heating tends to provide a more even heat distribution without the hot and cold spots caused in a forced air system by convection. (Bradford White Corporation, 2016; Hydronic Heating, 2016b; PB Heat, LLC., 2013) When it gets down to the physical infrastructure of hydronic heat versus forced air heating, radiant heating has three major advantages. First, if space constraints are a factor, the plumbing for a hydronic heat system tends to take up significantly less room than forced air ductwork. (Bradford White Corporation, 2016; Olesen, 2002) Second, when placed overhead, forced air ducting also tends to cause shading of plants within greenhouses. This is exemplified in the rooftop greenhouse located on Allegheny College’s Biology and Chemistry building. Third, the plumbing of a radiant heat system does not require any cleaning or maintenance after it is installed, as it is a closed loop system. (EWEB, n.d.; Olesen, 2002) As with any heating system, hydronic heat does have a few minor trade offs and easily addressed issues. Compared to forced air systems, hydronic radiant heat systems generally have a longer lag time between startup and realized change in building temperature. Once up to temperature, however, hydronic systems retain their heat much better than forced air systems. (Black Diamond Plumbing & Mechanical, Inc., 2013; Franco, 2017; Hydronic Heating, 2016b; KompareIt, 2017) Additionally, if the heat distribution piping of a hydronic setup develops a leak, two problems can follow. First, air can enter the distribution lines, causing an inefficiency of heat transfer, remedied by purging the lines of air. (EconoHeat, Inc., 2015; Franco, 2017) The second complication associated with plumbing leaks is risk of water damage to the enclosing building. In the Carrden Greenhouse application, any errant water from a leak is not likely to pose much threat to the structure as greenhouses, by design, are built to withstand humid conditions and irrigation inputs. The only other significant drawback to hydronic heat systems is the potential for boiler and distribution line freezing, and consequent damage to components, during a cold weather event that occurs while the boiler is shut down (not turned on for the season or turned off for 4 maintenance). (KompareIt, 2017) While a valid concern, freezing can be eliminated by introduction of antifreeze to the boiler water circuit. Many boiler manufactures have recommendations for antifreeze concentrations and approved brands/types. (EconoHeat, Inc., 2015) Considering the numerous benefits of WVO as a fuel source and hydronic heating as a means of distributing heat, the purpose of this comprehensive thesis is to examine the feasibility of using a WVO fueled boiler/hydronic heat system in Allegheny College’s Carrden Greenhouse. Preliminary Design Considerations: Heat Distribution: With this goal in mind, an early task of this study was to narrow down various hydronic heat system options to those that would best reflect the Carrden Greenhouse’s needs. The Carrden Greenhouse will have a fairly small footprint at only 12 feet by 16 feet, meaning that internal space will need to be used efficiently. As a teaching tool and demonstration model for a variety of pioneering technologies and growing methods, the Carrden Greenhouse will likely be a fluid structure in terms of its interior organization. At present, growing bed designs have not been finalized and growing methods are likely to evolve throughout the growing season, with bench top beds and/or pots as well as at-grade raised beds and/or in ground planters all being considered. Further, conversations with Kerstin Martin, Carr Hall Garden Manager, revealed that it is her intent to keep the greenhouse at roughly 35 degrees F for the first few winter seasons, simply maintaining plants rather than holding a higher temperature for crop production or seed germination. On the other end of the spectrum, Kerstin indicated that full winter production of a heat-intensive crop, such as tomatoes, would not be out of the question, requiring heating capacity up to 85 degrees F. (Boulton & Martin, 2017; Martin, 2017) As such, the primary consideration when choosing a heating system setup was to maximize flexibility in terms of future greenhouse interior design, growing bed construction, and temperature settings. Within the realm of hydronic heat/boiler systems, there are a number of options for system design and configuration that should be considered, including radiant floors, root zone heating, under-bed piping, unit heaters, and many more. These varying setups ultimately impact system efficiency, in turn impacting boiler sizing and fuel needs. Further, each design poses different limitations on space use within the greenhouse. Radiant floor heating, in which hot water pipes are either imbedded in or run below a floor surface, has numerous merits in terms of efficiency and even distribution of heat throughout a space. (USDOE, n.d.) However, such a system relies on the installation of flooring material such as concrete slabs, tile, wood, or layered subfloors that sandwich the water tubing. (Olesen, 2002; USDOE, n.d.) At the time of decision-making, greenhouse floor type had not been finalized. Concrete flooring was under 5 consideration, but was predicted to be cost-prohibitive, while dirt or gravel floors seemed like more feasible options. In order to maintain flexibility of final greenhouse design and to avoid timing conflicts between greenhouse build-out and radiant floor installation, this method of heat distribution was removed from consideration. Another heat distribution design possibility was root zone heating, wherein the hot water pipes run through or directly below the growing bed soil, thereby heating the roots of plants/crops and enabling ambient temperature in the greenhouse to be five to fifteen degrees Fahrenheit cooler than traditional heating methods, increasing the overall efficiency of the heating system. (Bartok, 2015; Bartok & Grubinger, 2012; Christenbury, 1990) In the 35 degree F temperature scheme proposed for the first few years of greenhouse operation, it would no longer be feasible to reap the efficiency benefits of root zone heating from lower ambient air temperature as the desired air temperature is already at the minimum for plant growth, thus removing the efficiency-creating temperature differential. Further, growing bed designs have not yet been finalized and adding in-soil piping would pose an additional layer of design complexity for the growing beds. While presently ruled out for the first iteration of the Carrden Greenhouse’s heating system design due to these factors, root zone heating remains an intriguing technology that should be considered for future use in the greenhouse, should operating temperature be increased to levels warm enough to realize the efficiency benefits of root zone heating. Future utilization of root zone heating may also pose an opportunity for Allegheny College to pioneer new heating methodology as literature reviews have revealed WVO-fueled greenhouses and greenhouses using root zone heating setups to be fairly common, but no examples of greenhouses using both technologies in conjunction were found. With this in mind, creating the capacity to add in root zone heating at a later time became a consideration in the component selection of the proposed Carrden Greenhouse system. (see Results/Discussion - Heating System Component Budget) Similar in concept to root zone heating, another option was to use exposed hot water pipes placed under raised growing beds. In this design, the soil and roots get the most direct heat rising from below while the ambient air is also warmed by the exposed pipes, which can be either finned or bare. (USDA ARS, 2016a) Again, bed designs have not been finalized and this system has been ruled out to allow for removal and/or reorganization of growing tables/benches as well as possibility of in-ground growing beds for which exposed below-bed piping would not work. Ultimately the heat distribution method that will be best suited to the Carrden Greenhouse is perimeter hot water piping. This design will maximize flexibility for greenhouse flooring options and various bed designs such as ground level, raised, or bench top growing beds. (Kovalycsik, 2016) By tucking the piping along the walls of the greenhouse, an open floor plan will be maintained with the heating infrastructure out of the way of any future reconfigurations of the interior growing space. In 6 larger greenhouse setups, a solely perimeter-based heat distribution setup may fail to keep the deep interior of the greenhouse warm enough, as perimeter heat is typically used to augment a primary, centrally distributed heat system. (Kovalycsik, 2016) This is not likely to be an issue for the Carrden Greenhouse given its relatively small footprint, heavy insulation, and low rate of air exchange (estimated at 0.5 exchanges per hour or lower per Virtual Grower software). (Ceres Greenhouse Solutions, 2016; USDA ARS, 2016a; Zanoni, 2017) The pipes in a perimeter heat system can be either finned or bare, with finned pipes having better heat distribution efficiency due to their greater element surface area. Boiler Intake and Ventilation: The next major design consideration relates to the air intake and exhaust of the boiler. Out of the box, many waste oil boilers are designed to draw combustion air from the room in which they are placed (atmospheric combustion) and expel exhaust gases via draft (gravity/natural ventilation) through a vertical chimney pipe extending above the roof peak. (See Figure 1 – Conventional Venting vs. Power Venting with Combustion Air) (Field Controls, LLC, 2008; Morrison, 2017b; Sims, 2015) A number of factors render this boiler configuration problematic for the Carrden Greenhouse. On the exhaust side of the boiler, use of a traditional vertical chimney pipe exiting through the roof would take away valuable space from a roof-based array of Luminescent Solar Concentrators that will supply electricity to the greenhouse and the electric grid. Further, a large chimney through the interior would take up valuable space in the relatively small structure. In light of this, a side/wall exit exhaust will be needed. On the intake side of the boiler, utilizing atmospheric combustion has the potential to cause a number of undesirable conditions. In atmospheric combustion, any air drawn into the boiler from within the structure will exit to the outside in the exhaust gases. As such, a negative air pressure is created within the greenhouse relative to the outside air. (ATI of NY, 2017; Sims, 2015) For every cubic foot of air evacuated from the building by atmospheric combustion, another cubic foot of air must enter the structure from the outside. (Sims, 2015) With this setup, the boiler is burning pre-heated air from inside the structure and sending it out the exhaust, thereby wasting some measure of already warm air, while drawing in cold outside air via negative structure pressure to replenish the air supply in the building. (ATI of NY, 2017; Sims, 2015) This makes atmospheric combustion a rather inefficient process. Alternatively, separated combustion utilizes a boiler air intake extending outside the structure and does not use any air from within the greenhouse. (ATI of NY, 2017; Sims, 2015) By separating the ambient air in the structure from the combustion air and exhaust system, no pressure differences are created between the inside and outside of the structure, eliminating colder air infiltration and waste of already heated air. This gives separated combustion systems the ability to be much more efficient than atmospheric combustion, with many separated combustion boilers and furnaces reaching up to and 7 beyond 90% efficiency. (Sims, 2015; USDA ARS, 2016b) While increased efficiency played a part in the decision to use separated combustion in the Carrden Greenhouse’s boiler heat system, a number of other factors came into play as well. For structures with many air gaps/high rates of air turnover, the negative pressure gradient created in atmospheric combustion can be balanced fairly quickly as outside air is able to move into the building rather easily. However, the Ceres greenhouse plans being adapted for the Carrden Greenhouse call for a very well sealed building, making for a very low air exchange rate (estimated to be 0.5 exchanges per hour or lower, per Virtual Grower software). (Ceres Greenhouse Solutions, 2016; USDA ARS, 2016a) With such a well-sealed structure, it is possible that outside air will not be able to enter the building quickly enough to balance the pressure differences created by removal of interior air. Under these conditions, the negative pressure in the structure may become great enough to drop or reverse exhaust draft (“back draft”), thereby causing a buildup of dangerous exhaust gases within the boiler and/or building that can lead to boiler explosion and/or lack of sufficient oxygen for human occupants. (ATI of NY, 2017; Sims, 2015) With separated combustion, negative pressure is not created within the structure, greatly reducing the risk of exhaust gas buildup. (Sims, 2015) Further, the outside air utilized by separated combustion tends to be cleaner than inside air used in atmospheric combustion. Within a structure, the air may contain vapors, such as those from cleaning agents, which can corrode burner/boiler parts as well as suspended particles, such as dust and dirt kicked up in a greenhouse, which can clog burners/boilers and necessitate more frequent cleaning. (ATI of NY, 2017; Sims, 2015) Likewise, air within a structure may contain errant flammable vapors that could cause an explosion when sucked into an atmospheric combustion boiler (same principal as keeping sinking flammable gases away from the pilot light on the furnace or hot water heater in a house). For these reasons, use of separated combustion/outside air can prolong the life of a boiler and extend the time between cleanings. (ATI of NY, 2017; Sims, 2015) Given the need for a side exit exhaust and separated combustion, the boiler in the Carrden Greenhouse heating system will need to utilize a combined power-venting device. Devices such as the industry standard Field Controls ComboVent CV-4 (See Results/Discussion - Heating System Component Budget) feature a blower motor that serves to suck exhaust gases out of the boiler, thereby removing need for natural draft, while drawing in external air to be supplied to the boiler’s burner assembly, all contained in one ventilation unit that is placed through an external wall of the structure. (See Figure 1 – Conventional Venting vs. Power Venting with Combustion Air) (Field Controls, LLC, 2008; Kreider, 2017; Morrison, 2017b) 8 Figure 1 – Conventional Venting vs. Power Venting with Combustion Air (Field Controls, LLC, 2008) Methods: Modeling Heating and Fuel Demand: In order to size a waste oil boiler for the Carrden Greenhouse, it was necessary to have an idea of the building’s heating demands during the maximum heating scenarios it might encounter. In order to calculate maximum BTU (British Thermal Units) output as well as fuel consumption throughout the heating season, I utilized a Virtual Grower, a software program produced by the U.S. Department of Agriculture, Agricultural Research Service to assist growers in determining heating and lighting costs, as well as crop production rates, for a variety of greenhouse setups in a theoretical computerized model. With numerous inputs to its model, Virtual Grower has become a widely used tool for growers around the country. (USDA ARS, 2017) Prior to running the model, Virtual Grower walks the user through a number of setup options, beginning with location to determine weather data. While Meadville, PA was not an available location setting in the software, I was able to select Franklin, PA for use in the model, roughly 30 miles southeast of Meadville and only 135 feet higher in elevation sitting at 1542 feet above sea level. (US Climate Data, 2017; USDA ARS, 2016a) Location settings in the software then draw from a historical weather database sourced from the National Renewable Energy Laboratory to gather “typical values of temperature, light, and cloud cover… for each hour over the course of 12 months.” (USDA ARS, 2016b) The weather data 9 then used in running the model is a representation of typical conditions for each day and time, not average values over a period of time. (See Figure 2 – Virtual Grower Typical Daily Light Integral and Temperature Range Data for Franklin, PA) (USDA ARS, 2016b) Figure 2 – Virtual Grower Typical Daily Light Integral and Temperature Range Data for Franklin, PA (USDA ARS, 2016a) 10 The next setup step is to tell the Virtual Grower program how the greenhouse is constructed, beginning with dimensions and shape. The Carrden Greenhouse designed by Ceres will ultimately have a single-sloped roof with no peak. (See Figure 3 – Example Ceres Greenhouse Solutions Greenhouse with Single-Slope Roof) (Ceres Greenhouse Solutions, 2016) While providing options for multi-peak, multiarch, half-arch, and Quonset-style, greenhouse shapes, Virtual Grower does not give the user an option for single slope roof designs with no peak. As such, I went with a traditional single-peak roof design (with a sloping roof on each side of the peak) in the model. (See Figure 4 – Virtual Grower Assumed Greenhouse Shape, with Materials Insulation Values) When setting the peak and top plate heights (eave overhang does not impact internal volume) equal for the model’s single peak roof to those of the high and low side, respectively, of the Ceres design single slope roof, the internal volume of the greenhouse above the top plate remains the same, even though shape is different. I set footprint dimensions at 11.125 feet by 15.5 feet to reflect the actual footprint of the Ceres 12 by 16 foot design. Side height was set at 7.1 feet with the roof peak at 8.92 feet to reflect the “high side” height of the real greenhouse’s single slope roof. (Ceres Greenhouse Solutions, 2016; Zanoni, 2017) These dimensions give the greenhouse a footprint of 172.4 square feet, a volume of 1381.2 cubic feet, and a surface area of 583.4 square feet. (USDA ARS, 2016a) Figure 3 – Example Ceres Greenhouse Solutions Greenhouse with Single-Slope Roof (Schiller, 2016) 11 Figure 4 – Virtual Grower Assumed Greenhouse Shape, with Materials Insulation Values (USDA ARS, 2016a) Virtual Grower then allows the user to select building materials for the greenhouse. The software assumes that each section of wall/roof is one continuous surface of the material selected, such as an entire wall of plastic sheeting in a hoop house. However, the Carrden Greenhouse will be more of a building, having well-insulated walls and a number of windows. (See Figure 3 – Example Ceres Greenhouse Solutions Greenhouse with Single-Slope Roof) As such, I manipulated the model by exaggerating the kneewall heights in the software to roughly reflect the sections of greenhouse surface that are not filled with windows. For example, my inputs to Virtual Grower were all four walls being constructed out of double pane glass with kneewall heights of three feet constructed of solid insulation foam. On the rear wall of the greenhouse, there will ultimately be no windows, but the Virtual Grower software does not allow for this option. Rather, the software model thinks that the rear wall is full double pane glass, with an insulation foam kneewall coming up to 7.1 feet to reflect the lack of windows in the real greenhouse. Note that the actual back wall of the final Carrden Greenhouse will be just shy of nine feet tall. As mentioned previously, I had to use a model greenhouse design with a center roof peak and top plate on both sides of 7.1 feet. As such, the software was not able to account for the roughly two foot difference in rear wall material height, which might ultimately cause a slight overestimation of heating demand. For 12 the greenhouse roof, I input single pane glass as the material to best reflect the construction of the Luminescent Solar Concentrators that will be installed. Virtual grower assumes the following material Uvalues and light transmittance values for the materials used in the model: Figure 5 – Virtual Grower Assumed Material U-values and Light Transmittance (USDA ARS, 2016b) Material -1 °F -1 -2 ft ) Glass U-value (Btu hr 1.13 Glass double layer 0.65 70 Solid insulation foam 0.23 0 Light Transmittance (%) 75 Virtual Grower then uses these material inputs to construct a model of the greenhouse that reflects overall insulation and light transmittance values for each part of the structure that are later used in heating calculations. (See results below and Figure 4 – Virtual Grower Assumed Greenhouse Shape, with Materials Insulation Values) (USDA ARS, 2016b) It is important to note that Virtual Grower does not take foundations or flooring into its building design algorithms as the software is primarily used for modeling much larger greenhouses or hoop houses with no floor. In the case of the Carrden Greenhouse, the floor surface will most likely be dirt or gravel with a greenhouse foundation comprised of concrete piers. Further, a “Swedish Skirt” design of horizontal, in-ground insulation may be employed in order to maintain a pocket to warmer ground underneath the greenhouse. (See Figure 6 – Example Swedish Skirt Insulation Design) (Ceres Greenhouse Solutions, 2015) Not factoring in this extra ground insulation would serve to slightly inflate Virtual Grower heating demand results. 13 Figure 6 – Example Swedish Skirt Insulation Design (Ceres Greenhouse Solutions, 2015) The next stage of building modeling revolves around air infiltration into the greenhouse. I selected inputs of no gaps in the structure, no malfunctioning vent covers, no permanently open outside air intakes, no adjoining buildings with separate heating systems, and no internal “air curtain”. Given the Carrden Greenhouse’s anticipated high insulation values and thorough air sealing, the Virtual Grower model set anticipated air exchange, or “number of volumes of air equivalent to the inside of your greenhouse [that] gets exchanged with outside air,” at 0.5 exchanges per hour, which is typical for a wellmaintained newer greenhouse structure. (USDA ARS, 2016b) Finally, Virtual Grower asks users to set up a model for the heating system. The software is capable of modeling a wide array of system designs from forced air to steam heat to boilers using many different distribution methods, fuel sources, and ventilation options. For the Carrden Greenhouse system, I input a hot water boiler with a software default operating efficiency of 78 percent. This value can be overridden at a later time for a specific manufacturer’s claimed boiler efficiency and is increased by use of separated combustion. Further boiler information included setting for new age of the boiler and annual boiler cleaning/maintenance, both of which were the best settings for efficiency. As described previously, the boiler was input with separated combustion, which increases overall building heating efficiency. Heat distribution was set to perimeter piping, with models later being run for both bare and finned piping. I was able to manually input the fuel source as WVO with a custom BTU capacity of 120,000 BTU per gallon. (AgSolutions, LLC, n.d.-b; Bartok, 2013) 14 Figure 7 – Example of Virtual Grower Heating System Setup Inputs for Carrden Greenhouse (USDA ARS, 2016a) From here, I was able to specify multiple heating schedules to run through the model that would reflect different heat settings that may be utilized in the greenhouse. Carr Hall Garden Manager Kerstin Martin intends to keep the greenhouse at 35 degrees F for the first few winters. (Boulton & Martin, 2017; Martin, 2017) I used this as a base temperature model of lowest demand on the system. In the future, if Martin wants to maintain a higher temperature in the greenhouse for crop production and seed germination, she suggested a temperature of 75 degrees F, which I used as my mid-level system demand heating scheme. In the event that the Carrden Greenhouse is used to grow a heat-intensive crop, such as tomatoes, throughout the winter, it is possible that temperature settings could reach as high as 85 degrees F. This temperature was set as the high-demand heating model, which is also the model from which boiler sizing can be determined. While the greenhouse may never be heated to 85 degrees F for a full winter, it is in everyone’s best interest if a boiler is selected that has this capacity in order to keep options open in the future and ensure that the heating system is able to cope with any unusually cold winter temperatures. 15 These three heating schemes, at 35, 75, and 85 degrees F, were each run through Virtual Grower’s output functions to gain data on maximum boiler BTU capacity needed for each heating schedule as well as amounts of fuel used on a yearly and monthly basis. Each heating scheme was run through the model twice, once with bare perimeter pipe heat distribution and once with finned perimeter pipe heat distribution to see if finned versus bare had any major effect on system efficiency, fuel use, and BTU output requirements. Fuel Availability: Prior to calculating heating needs for the Carrden Greenhouse, it seemed prudent to know how much Waste Vegetable Oil might be available on campus as a fuel source. At present, Allegheny College sells all of its used fryer oil from Brooks and McKinley’s dining halls to Buffalo Biodiesel Inc. After acquiring their monthly WVO pickup data for 11/2014 through 2/2016, I was able to generate estimates of how much fuel is available for a given year. At pickup, Buffalo Biodiesel tracks the WVO barrel’s percent fill, what percentage of the liquid in the barrel was usable oil (versus water, food scraps, sludge, etc.), and the total usable gallons collected over the data period. (Buffalo Biodiesel, Inc., 2016) No data was provided for total gallons of usable oil on a month-by-month basis. I was able to extrapolate data from the 16 month reporting period to find average usable gallons of WVO generated per month, per dining hall and per year, per dining hall. Combining these numbers gave total averages for all WVO available on campus in a given month or year. Boiler Selection: To begin the process of boiler selection, I initially created a cross-comparison spreadsheet of twelve waste oil burners, most of which were listed as capable of burning WVO. Of these twelve, five were immediately ruled out as they had BTU outputs far exceeding the output required of the Carrden Greenhouse under maximum possible heating demand, as found from the above heating demand methodology. From here, I called boiler manufacturers, researched more detailed model specifications, obtained pricing quotes, and compared included accessory components. Of the seven boilers still in consideration, three models were removed after finding that the manufacturer had either gone out of business or been absorbed by another manufacturer who discontinued the models, one was determined to be too large for the Carrden Greenhouse application, and one was not recommended for use with straight WVO by the manufacturer. This left two boiler models that were compared in depth. Of these, one was within the sizing needs and budget constraints while the other was more costly and had too large of a physical footprint relative to the greenhouse’s available interior space. 16 Component Selection and Pricing: With boiler selection narrowed down to one specific model that would best fit the needs of the Carrden Greenhouse, I obtained a formal price quote from the manufacturer for the boiler, freight costs, and a list of included accessories. Analysis of the boiler’s installation and service manuals provided insights as to additional components that would be needed for boiler operation and discussions with multiple boiler manufacturers gave an estimate of heat distribution piping quantity and cost. A list of anticipated equipment and materials needs was compiled and pricing information was gathered from a variety of heating system suppliers, such as Supply House, that were recommended by the boiler manufacturers. (Kreider, 2017; Morrison, 2017b, 2017c) 17 Results: Heating and Fuel Demand: Virtual Grower Outputs for BTU Demand and Fuel Consumption for Carrden Greenhouse Model Under Different Heating Schemes and Heat Distribution Setups Temp Set/Style Max BTU Output/hour * 35° F perimeter 35° F perimeter finned 75° F perimeter 22852 75° F perimeter finned 85° F perimeter 42300 85° F perimeter finned 47162 Total gal fuel/year 66.16 65.24 700.37 690.64 944.43 931.32 * “Largest heat loss rate for your greenhouse design, location, and heat schedule,” that the system will experience during a winter. (USDA ARS, 2016b) Virtual Grower Monthly Fuel Consumption Output for Carrden Greenhouse Model Under Different Heating Schemes and Heat Distribution Setups Temp Set / Style of Pipe: (gallons per month) 35° F 75° F perimeter 75° F perimeter 85° F finned perimeter finned perimeter 85° F perimeter finned Month: 35° F perimeter January 11.2 11.0 98.6 97.3 124.2 122.5 February 22.9 22.5 102.8 101.4 125.7 124.0 March 6.5 6.4 75.8 74.8 99.6 98.2 April 3.2 3.1 57.4 56.6 78.0 76.9 May 0.4 0.4 43.6 43.0 62.6 61.8 June 0.0 0.0 15.2 15.0 29.1 28.7 July 0.1 0.1 13.1 13.0 26.8 26.4 August 0.0 0.0 18.5 18.2 34.4 33.9 September 0.1 0.1 31.1 30.6 48.3 47.6 October 0.4 0.4 47.2 46.6 68.8 67.8 November 5.1 5.0 84.9 83.7 109.5 108.0 16.5 16.3 112.1 110.5 137.6 135.6 66.2 65.2 700.4 690.6 944.4 931.3 December Yearly Totals: (gal./year) 18 Fuel Availability: WVO Availability on Campus – Extrapolated from Buffalo Biodiesel Collection Data from 11/2014 to 2/2016 (Buffalo Biodiesel, Inc., 2016) McKinley’s Dining Hall Total usable oil collected over 16 month reporting period Avg. usable gal/month collected (total/16 months) Usable oil/year (monthly avg. * 12 months) 1869 gal 116.8 gal/month 1401.8 gal/year Brooks Dining Hall Total usable gal collected over 16 month reporting period Avg. usable gal/month collected (total/16 months) Usable oil/year (monthly avg. * 12 months) 1206 gal 75.375 gal/month 904.5 gal/year Combined Dining Halls: Total usable oil/year (sum yearly averages) 2306.25 gal/year This table examines the Buffalo Biodiesel collection totals over the reporting period for each dining hall, calculates average oil production per month, and uses that average to calculate the average usable oil available per dining hall, per year. 19 Boiler Selection: WVO Boiler Model Comparison Conclusion Capacity (BTU/hr) Burner Fuel Consumption (Gal/hr) Dimensions (Inches) Shipping Weight (lbs) Cost EconoHeat OMNI OWB-9 Recommended Boiler 76,500 Output 0.60 23 x 24 x 25 530 $6,719.00 Glenwood Econo-Flame WOB 7510 100,000 Output / 24 x 84 x 24 800 $7,400.00 KingBuilt KBB110 Too large of footprint and too expensive Manufacturer does not recommend straight WVO use Company appears out of business Company bought by INOV8, model no longer available Company bought by INOV8, model no longer available Data Source (EconoHeat Inc., 2015; Morrison, 2017a) (Glenwood Heaters, LLC, n.d.; Obadiah’s Wood Stoves, n.d.) INOV8 B120 Too Big Colombia LVWO AgSolutions B105 KingBuilt KBB85 60,000 to 168,000 Output 0.5 to 1.5 20x 20 x 43 490 / (Columbia Boiler Company, 2006) 105,000 Input 0.85 23 x 21 x 33 250 / (AgSolutions LLC, n.d.-a) 74,000 Output 0.6 to 0.75 26 x 24 x 34 330 / (KingBuilt, Inc., 2007) 98,000 Output 0.8 31 x 24 x 34 403 / 122,000 Output 0.95 34 x 24 x 34 476 / (KingBuilt, Inc., 2007) (INOV8 International, Inc., 2017) Note: other models examined that were ruled out immediately due to their far larger size than needed (200,000 BTU or greater output) include: CleanBurn CBT-200, EnergyLogic EL-200B, Lanair 9130MBX250, CleanEnergy CE-340WOB, and Alternate Heating AHS250 20 Component Selection and Pricing: Heating System Component Budget Component Boiler and Burner Circulator Pump Controls / Aquastat Air Compressor Fuel supply pump and filter Expansion tank Supply & Return Zone Manifold / Header Power Vent Controls for Power Vent Intake Ducting Exhaust Ducting Exhaust Ducting Exhaust Ducting Perimeter pipe Fuel storage tank(s) Misc. fittings, valves, and other expenses Unit Cost # Need Total Cost EconoHeat $6,719 1 $6,719 EconoHeat / 1 / EconoHeat / 1 / EconoHeat / 1 / Included w/ boiler EconoHeat / 1 / not needed / / / / Make/Model EconoHeat OMNI OWB-9 Included w/ boiler Included w/ boiler Honeywell L8148A Aquastat Included w/ boiler 1-1/2" Boiler Header with 3/4" Outlets (3 Branches) Field Controls ComboVent CV-4 Field Controls Oil Control Kit CK-61 4" x 8 Ft. Flexible SemiRigid Aluminum Duct w/ Clamps 4" by 2' Z-Vent Single Wall Pipe 4" x 45° Z-Vent Single Wall Elbow 5" (Crimped) to 4" Stainless Steel Reducer Slant/Fin E75 3/4" Baseboard Element - 5' Length, box of 2 Plastic caged cubes, drums Supplier Notes $29 2 $58 Patriot Supply Believe boiler has 1 1/2" output and return fittings. 3 branches allow up to 3 zones or split loops for system expansion in future. 4" connectors for intake and exhaust. Up to 170,000 BTU capacity. $418 1 $418 Supply House Should also look at kit models CK-62 and CK-63 $253 1 $253 Supply House Citation/ Source (Morrison, 2017a) (Morrison, 2017c) (MatcoNorca, 2017) (Field Controls, LLC, 2017a) (Field Controls, LLC, 2017b) $13 1 $13 $33 1 $33 (Lambro Industries, 2017) (Novaflex, Inc., 2017a) Supply House $39 2 $78 (Novaflex, Inc., 2017b) Supply House $24 1 $24 $78 10 $780 Free from local source / 1 / Rough estimate / / $500 Supply House Supply House Supply House Local Source Local Source This piece may need to be longer or shorter for building code Estimate based on (Kreider, 2017). 3/4 copper finned pipe can radiate 500 BTU/foot and need to radiate ~50k BTU to heat greenhouse. Therefore need ~100 feet of heating element TOTAL $8,876 21 (Novaflex, Inc., 2017c) (Kreider, 2017; Slant/Fin Corporation, 2017b, 2017a) Discussion: Heating and Fuel Demand: The Virtual Grower heating demand outputs provide a glimpse into the expected sizing needs of the boiler for the Carrden Greenhouse heating system. By analyzing numerous input variables pertinent to the Carrden Greenhouse’s design, the software is able to generate a report that includes maximum BTU output necessary to maintain the set temperature of the heating schedule during the harshest conditions of the heating season. This maximum BTU rating is the “largest heat loss rate for your greenhouse design, location, and heat schedule,” that the system will experience during a winter. (USDA ARS, 2016b) As such, the appropriate boiler for the structure must have a higher BTU output capacity per hour than this maximum demand number in order to be able to provide adequate heating under all circumstances. By sizing a boiler with capacity higher than the expected maximum demand, the system gains built in “headroom,” or a capacity safety buffer of sorts such that it may keep up with unexpectedly high heating demands from unusually low temperatures. As indicated in the results table above, the Carrden Greenhouse highest intensity heating schedule model (set point of 85 degrees F for full-winter tomato production) creates a maximum demand just shy of 50,000 BTU/hr. Consequently, any boiler purchased for the greenhouse’s system should therefore have a capacity of 50,000 BTU/hr or higher. Fuel Availability: The Virtual Grower outputs also report predicted fuel consumption for each heating scheme. Under the maximum intensity 85 degree F heating schedule, the system is predicted to use just shy of 950 gallons of WVO. Comparing this number to the roughly 2,300 gallons of WVO produced on campus annually, it is clear that there will be more than enough fuel available for the greenhouse. Brooks dining hall alone could nearly meet this fuel demand with its annual production around 900 gallons, and McKinley’s dining hall has ample stand-alone supply at approximately 1,400 gallons per year. Given the abundance of fuel from both locations relative to the heating system demand, the Carrden Greenhouse is afforded the opportunity to be picky in its fuel source; i.e. WVO can be gathered primarily from whichever dining hall is found to produce higher quality WVO in terms of low water, food, and sludge content, with the lower quality WVO still being sold to Buffalo Biodiesel Inc. or another purchaser for profit. Boiler Selection: In the world of commercial waste oil boilers capable of burning WVO, the Carrden Greenhouse’s 50,000 BTU/hr heating demand is a relatively low output requirement. Of the boilers in the waste oil market segment, most have minimum heating outputs of 200,000 BTU/hr or more, and only a handful fall 22 into the under 100,000 BTU/hr output range. As outlined in the methods section and boiler comparison table above that cross examines all of the potential boilers with outputs under 100,000 BTU, one boiler model clearly rises above the rest as the most suitable for use in the Carrden Greenhouse: the EconoHeat OMNI OWB-9. All other boiler models examined were too large, too expensive, or no longer available. The OWB-9 has a maximum output of 76,500 BTU/hr, exceeding our maximum heating requirements and providing ample headroom to address any uncharacteristically cold temperatures that may arise in the growing seasons ahead, and perhaps even meet the needs of any future greenhouse expansions. This boiler is significantly cheaper than the runner-up alternative Glenwood Econo-Flame WOB 7510, while including many more accessory components in the price. (See Discussion – Component Selection and Pricing below) (EconoHeat, Inc., 2015; Morrison, 2017a; Obadiah’s Wood Stoves, n.d.) Further, EconoHeat is one of the only boiler manufactures to fully endorse straight WVO fuel use in their boilers. I recommend purchase of the EconoHeat OMNI OWB-9 for the Carrden Greenhouse as the boiler around which to base the hydronic heating system. Component Selection and Pricing: Heating Elements/Piping: As noted in the methods for calculating heating system demand and fuel use, models were run for each of the three temperature schemes two separate times; once with finned perimeter piping for heat distribution and once with bare perimeter piping. This was done to look for differences in fuel use between the two heat distribution systems. Finned pipes were found to be more efficient in their fuel consumption compared to bare pipes for each heating schedule. In the model for the highest intensity 85 degree F heat schedule, the two fuel consumption totals were less than 15 gallons different over the course of an entire heating season. This is under a 1.4 percent difference in consumption. In a larger or less well-insulated and sealed greenhouse, these fuel consumption differences between finned and bare distribution pipes may be more drastic. Given that WVO will be a completely free fuel source for the Carrden Greenhouse, these small differences in fuel consumption between finned and bare pipe will have no impact on operating cost for the heating system as long as the WVO remains cost-free. As such, design of the perimeter piping system and selection of either bare of finned pipe will ultimately come down to materials cost. Finned pipe is more expensive, but has a much greater surface area and is therefore able to radiate far more BTUs per hour per foot of pipe, whereas bare pipe is cheaper but requires much more pipe footage to reach the surface area needed to transfer an equivalent amount of heat. There are many factors that go into the design of a heat distribution piping system to determine necessary pipe/element length, perhaps the most important of which is ensuring that the temperature of water returning to the boiler at the end of the 23 distribution loop(s) is within a certain range of tolerance for the boiler. If returning water is too cold, it can thermally shock the cast iron in the boiler, leading to boiler failure. (Morrison, 2016) While the numerous calculations needed to determine the layout of the heat distribution piping will ultimately need to be conducted by a HVAC professional, rough calculations can be run to estimate the cost of the heating elements/pipes. As noted previously, any given pipe has a thermal radiation capacity measured in the number of BTUs that can be transferred from the water per hour per foot of pipe. (Kreider, 2017; Slant/Fin Corporation, 2017a) Copper finned heating elements (such as those used in residential hydronic baseboard heaters) are able to radiate ~500 BTU/hr./ft. (Kreider, 2017; Slant/Fin Corporation, 2017b) The Carrden Greenhouse has a heating demand of ~50,000 BTU/hr. Some simple division then indicates that roughly 100 linear feet of copper finned heating element will therefore be needed in order to radiate enough heat to meet the building’s demands. (Kreider, 2017; Slant/Fin Corporation, 2017b) With this rough estimation on hand, it is then possible to estimate cost of heat distribution piping/elements, as represented in the budget breakdown in the Results section above. Included Equipment: The EconoHeat OMNI OWB-9 is a nearly turn-key package with the majority of the ancillary components necessary for operation included with the boiler. Included accessories include a circulator pump for the heating circuit(s); boiler controls and aquastat; on-board air compressor for atomization of fuel in the burner assembly; and a fuel supply pump, hose, and filter for connection to a fuel storage tank. (EconoHeat, Inc., 2015; Morrison, 2016) Further, EconoHeat has noted that an expansion tank is not likely to be needed with the OWB-9 boiler due to the low pipe pressure it runs. (Morrison, 2017c) Manifold/Header: As noted previously, root zone heating will not be utilized in the initial iteration of the Carrden Greenhouse heating system, but it would be wise to keep the option open for a root zone system in the future. As such, a manifold/header is needed for both the water output and return sides of the boiler in order to split the system into multiple heating circuits/zones. The OWB-9 boiler has 1 ½ inch pipe fittings for both output and return, leading me to select a manifold that splits 1 ½ inch pipe into three ¾ inch outputs/returns. (EconoHeat, Inc., 2015) This three branch manifold/header will enable up to three heating zones to be used off of one boiler, thereby allowing for addition of a root zone heating circuit in the future or even splitting of the perimeter heat circuit into smaller circuits in order to independently control temperature/flow or to shorten the loops so as to reduce water heat loss and risk of thermal shock to the boiler. (Matco-Norca, 2017) Manifolds/headers with different fitting sizes are also available. Ventilation: While conducting boiler comparisons, multiple manufactures recommended use of a Field Controls brand Power Venter in order to perform separated combustion with an outside air intake and 24 through-wall horizontal exhaust. (Kreider, 2017; Morrison, 2017b) The Field Controls ComboVent is specifically designed for use with oil boilers and combines powered ventilation of the exhaust with a connector for a fresh outside air supply to the boiler’s burner assembly. (Field Controls, LLC, 2008) The CV-4 model of ComboVent is capable of venting boilers with up to 170,000 BTU capacity, well above the needed venting power of the OWB-9 boiler. (Field Controls, LLC, 2008) Further, the CV-4 is capable of handling the OWB-9’s five inch exhaust flue. (EconoHeat, Inc., 2015; Field Controls, LLC, 2008) Installation of a ComboVent will require a control system that automatically turns on the vent any time the boiler’s burner starts up, monitors negative pressure in the exhaust ducting, and post-purges the system of exhaust gasses after the burner shuts back off. Field Controls makes three different models of controller for their ComboVent line, from which the eventual boiler installer should choose the model most suited to the Carrden Greenhouse’s needs. (Field Controls, LLC, 2008) The rest of the ventilation system will be comprised of intake and exhaust ducting, the latter of which must have sufficient vertical rise to meet boiler and building code requirements. (EconoHeat, Inc., 2015) Next Steps: Going forward, it will be necessary to hire an HVAC professional to perform the installation of the boiler and design the heat distribution pipe system in order to ensure sufficient heat distribution throughout the structure and proper wiring, plumbing, and venting of the boiler to meet manufacturer and building code requirements. In the meantime, Allegheny College can move forward with purchase of the EconoHeat OMNI OWB-9 boiler, Field Controls CV-4 ComboVent, and other finalized system components under the Constellation Energy to Educate Grant Program funding. (Stockwell, 2016) Fuel handling will be another hurdle to address, as systems will need to be developed to collect and store fuel from the dining halls. A fuel tank inside the greenhouse will be necessary for supplying the boiler while keeping the WVO warm enough to prevent sludge buildup and high oil viscosity. Additionally, long-term fuel storage tanks will be needed to allow WVO to sit and settle out any water, food bits, or other contaminants prior to consumption in the boiler. (Morrison, 2016) Prior to the first heating season, it would be advisable to collect WVO well in advance to begin this settling process. As with any fuel handling, safety and environmental regulations, such as secondary containment requirements, must be examined and met. 25 Works Cited (APA 6th ed.): Addison, K. (2005, April 8). Journey to Forever’s forced-air biofuel heater. Journey to Forever. Retrieved from http://journeytoforever.org/biofuel_library/ethanol_motherearth/me9.html AgSolutions, LLC. (n.d.-a). Waste Oil Burners / Heaters: B-105. Retrieved December 10, 2016, from http://www.agsolutionsllc.com/waste-oil-burners/waste-oil-burners-heaters-B105.htm AgSolutions, LLC. (n.d.-b). Waste Oil Heater Frequently Asked Questions. Retrieved December 13, 2016, from http://www.agsolutionsllc.com/waste-oilburners/waste_oil_burning_facts.html#What_is_the_BTU_potential_of_a_typical_gallon_of_was te_oil_ Allegheny College. (2017). Carr Hall Garden. Retrieved February 20, 2017, from http://sites.allegheny.edu/envsci/facilities/carr-hall-garden/ Allegheny News and Events. (2017, January 30). Allegheny College Awarded $37,500 Grant to Heat, Power Greenhouse. Retrieved from http://sites.allegheny.edu/envsci/2017/01/30/alleghenycollege-awarded-37500-grant-to-heat-power-greenhouse/ ATI of NY. (2017). DRP Separated Combustion Unit Heater. Retrieved March 9, 2017, from http://www.atiofny.com/products/gas-fired-heating-ventilation/drp-separated-combustion-unitheater/ Bartok, J., Jr. (2013). Fuels and Alternate Heat Sources for Commercial Greenhouses. Retrieved December 14, 2016, from https://ag.umass.edu/greenhouse-floriculture/fact-sheets/fuels-alternateheat-sources-for-commercial-greenhouses Bartok, J., Jr. (2015, March 6). Root Zone Heat - Installation Techniques. Retrieved April 15, 2016, from https://ag.umass.edu/fact-sheets/root-zone-heat-installation-techniques Bartok, J., Jr., & Grubinger, V. (2012, March 23). Root Zone Heating Systems for Greenhouses. Retrieved April 15, 2016, from http://articles.extension.org/pages/59546/root-zone-heatingsystems-for-greenhouses Belson, R. (2017, February 9). College Receives Grant to Construct Greenhouse. The Campus, pp. 1–5. Meadville, PA. Black Diamond Plumbing & Mechanical, Inc. (2013, November 25). Comparing Forced-Air Heating to Radiant Options. Retrieved April 3, 2017, from https://blackdiamondtoday.com/article/comparing-forced-air-heating-radiant-options Boulton, K., & Martin, K. (2017, February 8). Notes From 2/8/17 Meeting with Kelly Boulton and Kerstin Martin. Bradford White Corporation. (2016). Hydronic Heating - What it is and why you want it! Retrieved April 15, 2016, from http://www.laars.com/hydronic-heating.aspx Buffalo Biodiesel, Inc. (2016). McKinley and Brooks Pickup Reports 11/03/2014 - 02/29/2016. Tonawanda, NY. 26 Carbone, I., Boulton, K., & Pallant, E. (2016). Growing zero waste, organic food using multiple forms of sustainable energy: photovoltaics, biomass, and waste vegetable oil (Constellation E2 Energy to Educate Grant Proposal). Meadville, PA: Allegheny College. Ceres Greenhouse Solutions. (2015, January 15). Insulating Your Foundation. Retrieved from http://www.ceresgs.com/solar-greenhouse-basics-insulating-your-foundation/ Ceres Greenhouse Solutions. (2016). 12 x 16 Greenhouse Plans (No. CERS16-16478) (pp. 1–30). Ft. Collins, CO. Christenbury, G. D. (1990). Energy Management With Root-Zone Heating (No. EC 662) (pp. 1–11). Clemson University Cooperative Extension Service. Retrieved from http://www.clemson.edu/psapublishing/PAGES/HORT/EC662.pdf Clean Burn. (2016). About Waste Oil. Retrieved April 15, 2016, from https://www.cleanburn.com/oilrecycling/about-waste-oil/ Collins, M. (2009). Alternative Fuels in the Greenhouse. Small Farm Digest, 1–4. Columbia Boiler Company. (2006). Columbia LVWO Waste Oil Boiler Specifications and Data (No. MIP-2660). Pottstown, PA. Retrieved from http://www.columbiaboiler.com/docs/models/lvwo/LVWOspecsheet.pdf EconoHeat, Inc. (2015). Waste Oil Fired Boiler - Installation, Operation, and Service Manual: OWB-9, OWB-15 120v (pp. 1–36). Spokane Valley, WA. Retrieved from http://www.econoheat.com/manuals/OWB-9,_-15_Furnace_Manual_for_120V.pdf EWEB. (n.d.). Hydronic Heating Systems. Retrieved April 15, 2016, from http://www.eweb.org/saveenergy/home/hydronic Field Controls, LLC. (2008). Oil Venting Guide (pp. 1–14). Kinston, NC. Retrieved from http://www.fieldcontrols.com/filebin/pdfs/4318OilVentingGuide.pdf Field Controls, LLC. (2017a). Field Controls CV-4. Retrieved March 27, 2017, from http://www.patriotsupply.com/products/showitem.cfm/FIELD_CONTROLS_46521801# Field Controls, LLC. (2017b). Oil Control Kit w/ Electronic Post Purge. Retrieved March 27, 2017, from http://www.supplyhouse.com/Field-Controls-CK-61-Oil-Control-Kit-w-Electronic-Post-Purge Franco, M. (2017). Baseboard Heating 101. Retrieved April 3, 2017, from https://www.bobvila.com/slideshow/9-sneaky-ways-to-cut-your-home-heating-bills-49500/howto-save-electricity Glenwood Heaters, LLC. (n.d.). Glenwood Econo-Flame Waste Oil Boiler Brochure (pp. 1–2). Middletown, PA. Retrieved from http://woodstoves.net/documents/Glenwood%20Heaters/Econoflame_Waste_oil_Boiler_Brochur e.pdf 27 Grubinger, V. (2008, December 1). Heating a Greenhouse with Waste Vegetable Oil. Growing. Retrieved from http://www.growingmagazine.com/vegetables/heating-a-greenhouse-with-waste-vegetableoil/ Harper, W. S., & Grubinger, V. (2008, November 13). Using Waste Vegetable Oil in a Clean Burn Furnace for Greenhouse Heat and Electrical Power from Photovoltaics. The University of Vermont. Retrieved from http://www.uvm.edu/vtvegandberry/meetings/Cedar%20Circle%201113-08.pdf Hydronic Heating. (2016a). How Does Hydronic Heating Work? Retrieved April 15, 2016, from http://www.hydronicheating.net/how-it-works.html Hydronic Heating. (2016b). Hydronic Heating Vs Gas Forced Air Heating. Retrieved April 15, 2016, from http://www.hydronicheating.net/hydronic-vs-gfa.html Hydronic Heating. (2016c). Types of Radiant Heating Systems. Retrieved April 15, 2016, from http://www.hydronicheating.net/types.html Hydronic Heating. (2016d). What are the Benefits of a Hydronic Heating System? Retrieved April 15, 2016, from http://www.hydronicheating.net/benefits.html INOV8 International, Inc. (2017). INOV8 Multi-Fuel Waste Oil Burning Boilers (pp. 1–2). La Crosse, WI. Retrieved from http://cdn.shopify.com/s/files/1/0206/4088/files/BBoiler_Brochure_2012.pdf?1430 KingBuilt, Inc. (2007). KBB Series Multi-Oil Fired Boiler Systems (pp. 1–9). Eau Claire, WI. Retrieved from http://kingbuilt.com/images/KingBuilt_Boiler_Brochure.pdf KompareIt. (2017). Compare a Boiler vs a Furnace Costs. Retrieved April 3, 2017, from http://www.kompareit.com/homeandgarden/hvac-compare-boiler-vs-furnace.html Kovalycsik, M. (2016). Get Greater Flexibility With Perimeter Heat. Retrieved April 3, 2017, from http://www.deltatsolutions.com/enews/GreenhousePerimeterHeat.html Kreider, J. (2017, March 27). Phone Conversation with John Kreider, Owner, Glenwood Heaters, LLC [Phone]. Lambro Industries. (2017). 4" x 8 Ft. Flexible Semi-Rigid Aluminum Duct w/ Clamps. Retrieved April 2, 2017, from http://www.supplyhouse.com/Lambro-Industries-3120L-4-x-8-Ft-Flexible-SemiRigid-Aluminum-Duct-w-Clamps Leue, T. (2002, September 22). New use for waste vegetable oil. Retrieved from http://www.informconnect.org/communities/alldiscussions/printmessage?MID=1637&Printable=1&ssopc=1 Leue, T., & Horowitz, S. (n.d.). Yellow Heat Burner. Retrieved April 15, 2016, from http://www.yellowheat.net/burner.html Martin, K. (2017, January 27). Notes From 1/27/17 Meeting With Kerstin Martin. 28 Matco-Norca. (2017). 1-1/2“ Boiler Header with 3/4” Outlets (3 Branches). Retrieved April 2, 2017, from http://www.supplyhouse.com/HydroPEX-1-1-2X3-4Header-3-1-1-2-Boiler-Header-with-3-4Outlets-3-Branches-9680000-p Morrison, B. (2016, December 2). Phone Conversation with Britt Morrison, Sales Representative, Econo Heat, Inc. [Phone]. Morrison, B. (2017a). Updated Allegheny College OWB-9 Price Quote (No. 123106–270317) (p. 1). Spokane Valley, WA: Equipment Pros, Inc. Morrison, B. (2017b, February 8). Phone Conversation with Britt Morrison, Sales Representative, Econo Heat, Inc., Regarding Boiler Venting Options [Phone]. Morrison, B. (2017c, March 27). Phone Conversation with Britt Morrison, Sales Representative, Econo Heat, Inc., Regarding Boiler Pricing [Phone]. Novaflex, Inc. (2017a). 4" x 2’ Z-Vent Single Wall Pipe. Retrieved April 2, 2017, from http://www.supplyhouse.com/Z-FLEX-2SVEPWCF0402-4-x-2-Z-Vent-Pipe-9790000-p Novaflex, Inc. (2017b). 4" x 45° Z-Vent Single Wall Elbow. Retrieved April 2, 2017, from http://www.supplyhouse.com/Z-FLEX-2SVEEWCF0445-4-Z-Vent-45-Elbow-9780000-p Novaflex, Inc. (2017c). 5“ (Crimped) to 4” Stainless Steel Reducer. Retrieved April 2, 2017, from http://www.supplyhouse.com/Z-FLEX-2RD5R4X-5-Crimped-to-4-Stainless-Steel-Reducer Obadiah’s Wood Stoves. (n.d.). Glenwood Econo Flame 7510 Waste Oil Boiler. Retrieved December 10, 2016, from http://woodstoves.net/glenwood-heaters/econo-flame-7510-waste-oil-boiler.htm Olesen, B. W. (2002). Radiant floor heating in theory and practice. American Society of Heating, Refrigeration and Air Conditioning Engineers, Inc. Journal, 44(7), 1–19. Pahl, G. (2007). Straight Veg. In The Citizen-Powered Energy Handbook: Community Solutions to a Global Crisis (pp. 218–223). Chelsea Green Publishing. Retrieved from https://books.google.com/books?id=ShOtOrhOIrEC&pg=PA221&lpg=PA221&dq=greenhouse+ heat+wvo&source=bl&ots=7UIMhksiBq&sig=TuEEdyO_9FZb7vy2IM7TekyyFv0&hl=en&sa= X&ved=0ahUKEwjfsfq7z4_MAhXLcj4KHbe6Ats4ChDoAQgwMAQ#v=onepage&q=greenhous e%20heat%20wvo&f=false PB Heat, LLC. (2013). Hydronic Heating Basics. Retrieved April 15, 2016, from http://www.peerlessboilers.com/Products/WhyPeerless/HydronicHeatingBasics/tabid/189/Default .aspx Schiller, L. (2016, August 31). Year-Round Greenhouse. Retrieved from http://www.ceresgs.com/yearround-greenhouse_ceres-greenhouse_twarry/ Shepley, J. (2010). Assess and Quantify the Benefit of Alternative and Renewable Energy for Greenhouse Operations (SARE Project Report No. FNE07-620) (pp. 1–19). Sustainable Agriculture Research and Education. Retrieved from http://mysare.sare.org/wp-content/uploads/939176fne07-620.pdf Sims, J. (2015, January 26). Furnace Combustion: Atmospheric vs. Sealed. Retrieved March 9, 2017, from http://www.simsheatingandcooling.com/blog/furnace-combustion-atmospheric-vs.-sealed 29 Slant/Fin Corporation. (2017a). Bare Elements Product Information Sheet (pp. 30–31). Mississauga, Ontario. Retrieved from http://s3.supplyhouse.com/product_category_files/Slant%20Fin%20%20Cat%2018172%20-%20Product%20Overview.pdf Slant/Fin Corporation. (2017b). E-75, 3/4" Baseboard Element - 5’ Length. Retrieved March 27, 2017, from http://www.supplyhouse.com/Slant-Fin-101002050-E-75-3-4-Baseboard-Element-5-Length Stockwell, C. (2016, November 16). Constellation E2 Energy to Educate Award Notification. Constellation, an Exelon Company. Turner, R. F., & Turner, L. L. (2016). Renewables. Retrieved April 15, 2016, from http://www.laughingstockfarm.com/renewables/ US Climate Data. (2017). Geography and Map: Meadville, PA. Retrieved March 9, 2017, from http://www.usclimatedata.com/climate/meadville/pennsylvania/united-states/uspa1020 USDA ARS. (2016a). Virtual Grower (Version 3.0). U.S. Department of Agriculture - Agricultural Research Service. Retrieved from https://www.ars.usda.gov/research/software/download/?softwareid=309 USDA ARS. (2016b, May 2). Manual for Virtual Grower 3.0. U.S. Department of Agriculture Agricultural Research Service. Retrieved from https://www.ars.usda.gov/research/software/download/?softwareid=309 USDA ARS. (2017, February 28). Virtual Grower 3 Model. Retrieved March 10, 2017, from https://www.ars.usda.gov/midwest-area/wooster-oh/application-technology-research/docs/virtualgrower-3-model/ USDOE. (n.d.). Radiant Heating. Retrieved March 8, 2017, from https://energy.gov/energysaver/radiantheating USGS. (2016, May 3). Transpiration - The Water Cycle. Retrieved May 6, 2016, from http://water.usgs.gov/edu/watercycletranspiration.html Zanoni, B. (2017, January 25). Greenhouse Dimensions [Email]. 30