Lineset App Data Sheet E1fb 90-240

Transcript

APPLICATION DATA SHEET General Piping Recommendations and Refrigerant Line Length for Split-System Air Conditioners and Heat Pumps INTRODUCTION The tables and application data in this publication will help you to better apply split system cooling and heat pump systems to achieve maximum efficiency and performance, improved reliability, and greater customer satisfaction. This guideline includes information for: • General piping practices • Vapor and liquid line sizing • Total line length limitations • Elevation limitations • Orifice changes • Slope horizontal suction lines on cooling only systems approximately 1 inch every 20 feet toward the outdoor unit to facilitate proper oil return. Since the flow of refrigerant is bi--directional on heat pumps, all horizontal vapor lines should be level. Pre--charged lines with excess tubing should be coiled horizontally in an inconspicuous location to avoid oil trapping. Never coil excess tubing vertically. • Use long radius elbows wherever possible, except when fabricating oil return traps. Short radius elbows should be used on traps to keep the oil volume returning to the compressor as small as possible. See Figure 2. • System charging • Special considerations for long line lengths (2) SHORT RADIUS 45° STREET ELBOWS GENERAL GUIDELINES The following guidelines apply to the application on either factory line sets or field fabricated tubing for cooling only and heat pump systems: • Many service problems can be avoided by taking adequate precautions to provide an internally clean and dry system and by using procedures and materials that conform with established standards. • The lines should be installed so that they will not obstruct service access to the indoor coil, air handling system or filter. Install the lines with as few bends as possible. Care must be taken not to damage the couplings or kink the tubing. Care must also be used to isolate the refrigerant lines to minimize noise transmission from the equipment to the structure. • Never solder vapor and liquid lines together. They can be taped together for convenience and support purposes, but they must be completely insulated from each other. 90° SHORT RADIUS ELBOW FIGURE 2 - Recommended Construction of oil traps • Use PVC piping as a conduit for all underground installations. See Figure 3. Buried lines must be kept as short as possible to minimize the build up of liquid refrigerant in the vapor line during long periods of shutdown. If runs exceed 10 feet, an accumulator must be installed on cooling only units. • Support all refrigerant lines at minimum intervals with suitable hangers and brackets. Tape and suspend the refrigerant lines as shown in Figure 1. DO NOT ALLOW METAL--TO--METAL CONTACT. FIGURE 3 - Underground Application FIGURE 1 - Refrigerant Line Support Unitary Products Group • Pack fiberglass insulation and a sealing material such as permagum around refrigerant lines where they penetrate a wall to reduce vibration and to retain some flexibility. 036-61920-001 Rev. C (502) 036-61920-001 Rev. C (502) • Do not install a filter drier since one is factory installed in every outdoor unit. • Insulate all vapor lines with a minimum of 1/2 inch of foam rubber. Liquid lines that will be exposed to direct sunlight must also be insulated. The following additional guidelines apply to field fabricated piping: • Use hard drawn “L” type copper tubing where no appreciable amount of bending around pipes or obstructions is necessary. If soft copper must be used, care should be taken to avoid sharp bends which may cause a restriction. ELEVATION DIFFERENCES Elevation differences between the indoor and outdoor units can cause system performance and reliability problems if special considerations are not made to line sizes and orifice sizes. Both of these are covered in detail in the Line Sizing section below. LINE SIZING Every split system unit is shipped with a factory--mounted sweat fitting. Standard system fittings are shown below: (Refer to the unit instructions for specific size used.) Unit Size 012 to 024 030 to 036 042 to 060 • Braze all copper to copper joints with Silfos--5 or equivalent brazing material. DO NOT USE SOFT SOLDER. • During brazing operations, flow an inert gas such as nitrogen through the system to prevent internal scaling and contamination. • NEVER ADD OIL TO THE SYSTEM TOTAL LINE LENGTH The total length of interconnecting tubing is the sum of all horizontal and vertical runs from the indoor unit to the outdoor unit. Total measured line lengths are limited to: Heat Pump Cooling UNIT SIZE 012 to 060 012 to 018 024 to 060 LINE LENGTH 75 or 125 feet* 125 feet 175 feet * See Heat Pump installation instructions for correct maximum line length. The limiting factor on heat pumps is the storage capacity of the accumulator. The limiting factor on cooling units is oil sump capacity in the compressor. Total equivalent line lengths must only be used when calculating pressure drop. Therefore use the following table to calculate equivalent lengths for elbows. (NOTE: See Figure 2 for number of ells in suction line trap.) Table 1: Equivalent Lengths of Elbows LINE SIZE INCHES (O.D.) 1/4 5/16 3/8 1/2 5/8 3/4 7/8 1-1/8 90°° SHORT RADIUS ELBOW (FT.)* 0.7 0.8 0.9 1.2 1.5 1.6 1.8 2.4 90°° LONG RADIUS ELBOW (FT.) 0.6 0.7 0.8 1.0 1.3 1.4 1.6 2.0 *Two 45° radius ells equals one 90° radius ell. 2 Liquid Line OD 3/8" 3/8" 3/8" Vapor Line OD 5/8" 3/4" 7/8" 1-1/8” on E4TS For split system heat pumps, interconnecting refrigerant lines should be sized to match the factory supplied fittings. Vapor lines may be increased by one size to minimize pressure drop. Liquid lines must NEVER be increased or decreased. The additional charge required for larger liquid lines will overflow the accumulator in the heating cycle. For cooling systems where the indoor and outdoor sections are installed at the same elevation, refrigerant line sizes can usually be matched with the factory supplied fittings. There are a few exceptions for total line lengths exceeding 100 feet where pressure drop limitations are exceeded. In some cooling system applications, especially where elevation differences exist between the indoor and outdoor sections, suction and liquid line sizes can be increased (or decreased) to minimize pressure loss (or gain) and improve oil return to the compressor. When sizing refrigerant lines for split system cooling units, the following factors must be considered: 1. 2. 3. 4. Suction line pressure loss due to friction. Suction line velocity for oil return. Liquid line pressure loss due to friction. Liquid line pressure loss (or gain) due to static head. The effects that each of these factors have on a cooling system depend on the orientation of the indoor and outdoor sections; e.g., indoor unit above the outdoor unit. Before we discuss the various orientations, it is important to understand a few things about suction and liquid lines. First, let's consider suction lines. Suction pressure loss reduces system capacity by 1% per psi. This can be a serious problem if suction lines are not sized properly and pressure loss is 8 or 9 psi. Therefore, in order to minimize capacity loss and maximize efficiency, suction pressure loss must be minimized. This is achieved by increasing the size of the suction line. As a good achievable guideline, suction pressure loss should not be allowed to exceed 3 psi (5 psi for R-410A). Unitary Products Group 036-61920-001 Rev. C (502) Another important consideration when sizing suction lines is refrigerant gas velocity in a suction riser in cooling and 500 ft. in heating. Velocity of at least 1000 (1250 FPM-R410A) feet per minute is required to carry oil up a suction riser. Of course, this is only a factor when the outdoor unit is above the indoor unit and the oil must overcome the pull of gravity to return to the compressor. Greater refrigerant velocities are obtained by decreasing the size of the suction line. In applications where smaller tubing is required for a suction riser and larger tubing is needed to minimize pressure drop, the riser must be sized to achieve a velocity of at least 1000 feet per minute while the horizontal runs can be sized larger to minimize pressure drop. Liquid lines must also be sized to minimize pressure change. The total pressure change in a liquid line is the sum of the loss due to friction and the loss (or gain) due to static head in the vertical line. Liquid pressure loss reduces the amount of liquid sub--cooling at the rate of 1 degree for every 3 psi of pressure loss. If the liquid pressure drop is high enough to deplete all of the liquid sub--cooling in a system, liquid will start to flash reducing the refrigerant flow through the indoor coil metering device. Although a system can tolerate some flash gas at the metering device, under certain conditions the indoor coil can be starved and the coil will freeze. As a general guideline, total liquid pressure loss must never exceed 30 psi. R-407C has the same piping requirements as R-22. INDOOR UNIT ABOVE OUTDOOR UNIT With this configuration, a common problem with the cooling cycle (air conditioning or heat pump) is that the amount of liquid sub--cooling varies as operating conditions change (such as outdoor ambient). Under some conditions, it is possible that flashing will actually occur in the liquid riser. As long as only liquid is present in the liquid riser, the liquid static pressure loss can be calculated at 1/2 psi per foot of rise. However, as soon as flashing starts, the rate of pressure loss increases and continues to increase as the amount of gas increases. For this reason, the restrictions on elevation differences for this configuration must be based on the entire range of operating conditions. When the indoor unit is above the outdoor unit, the pressure loss in the liquid line during the cooling cycle will limit the amount of elevation difference allowed. Since both friction and static head contribute to pressure loss, it can be stated that the elevation difference allowed decreases as the total equivalent line length (horizontal plus vertical) increases. Table 2 shows elevation limits for each size unit with various size liquid lines over a range of total line lengths. This table should be used to size liquid lines based on the total equivalent line length of the system and the amount of rise required for the installation. Never exceed the elevation limit shown and always choose the smallest liquid line possible to minimize the total system charge. For example, a 3 ton system with 100 feet of total equivalent line length and 35 feet of lift will require a 3/8 liquid line. The same system with only 5 feet of lift will require a 5/16 liquid line. Unitary Products Group Remember, never increase liquid line size on heat pumps. Table 2: Elevation Limits - Indoor Unit Above Outdoor Unit FRIC- TOTAL EQUIV. LINE LENGTH - FEET TION UP UNIT LINE LOSS TO 50 *75 100 *125 150 175 SIZE SIZE PSI/ 25 100 ft. MAXIMUM ELEVATION - FEET 1/4 15.0 25 45 38 30 22 15 8 12 5/16 3.7 25 50 50 50 50 49 47 12 NR NR NR NR 28 1/4 32.0 25 37 33 40 44 48 50 25 18 5/16 7.8 50 50 50 50 50 50 25 2.7 3/8 5/16 12.5 25 48 41 35 29 22 16 24 3/8 4.8 25 50 50 50 48 46 43 5/16 19.0 25 41 32 22 12 3 NR 30 3/8 7.1 25 50 49 46 42 39 35 5/16 26.0 25 34 21 8 NR NR NR 36 3/8 9.7 25 50 45 41 36 31 26 1/2 2.1 25 50 50 50 50 50 50 3/8 12.0 25 48 42 36 30 24 18 42 1/2 2.7 25 50 50 50 50 50 50 3/8 17.5 25 42 34 25 16 8 NR 48 1/2 3.8 25 50 50 50 50 49 47 3/8 24.4 25 38 23 11 NR NR NR 60 1/2 5.3 25 50 50 49 47 44 41 * = 75 or 125 feet maximum total line length depending on model (see heat pump installation instructions for correct maximum line length.) NR = Not Recommended As a result of liquid line pressure drop, system capacity is lost because the flow of refrigerant through the expansion device is reduced. To compensate for this pressure drop, the orifice device can be increased in size to allow more refrigerant through. Table 3 shows orifice corrections for various ranges of liquid pressure losses. Friction losses can be calculated using Table 4, which shows pressure drop per 100 feet for various liquid line sizes. Static pressure loss can be calculated at 1/2 psi per foot of rise. REMEMBER, TOTAL PRESSURE LOSS IS THE SUM OF THE FRICTION AND STATIC LOSSES. Example: Given a 3 ton system with a #63 orifice, 5/16 liquid line, total equivalent piping length of 75 feet and 20 feet of liquid line lift; Friction loss Static loss = 75 ft. x 26 psi/100 ft. = = 20 ft. x 1/2 psi/ft. = Total loss = 19.5 psi 10.0 psi 29.5 psi From Table 3, increase orifice from #63 to #67. 3 036-61920-001 Rev. C (502) With this unit configuration, suction gas velocity is not a problem because oil can flow down to the outdoor unit. Therefore, the only consideration with the suction line is pressure loss. Table 5 shows pressure drop per 100 feet for various suction line sizes. This table should be used to size suction lines to minimize pressure drop. OUTDOOR UNIT ABOVE INDOOR UNIT Elevation differences for this configuration are limited to the following: Heat Pumps Cooling Table 3: Recommended Orifice Size LIQUID LINE PRESSURE LOSSES (PSI) 51 41 31 21 11 STANDARD 11 21 ORIFICE Thru Thru Thru Thru Thru Thru Thru SIZE 60 50 40 30 20 20 30 CORRECTED CORRECT ORIFICE SIZE ORIFICE SIZE 39 41 43 45 39 41 43 45 47 41 43 45 47 49 51 53 55 43 45 47 49 51 53 55 57 45 47 49 51 53 55 57 59 47 49 51 53 55 57 59 61 49 51 53 55 57 59 61 63 51 53 55 57 59 61 63 65 53 55 57 59 61 63 65 67 55 57 59 61 63 65 67 69 57 59 61 63 65 67 69 71 59 61 63 65 67 69 71 73 61 63 65 67 69 71 73 75 63 65 67 69 71 73 75 78 65 67 69 71 73 75 78 81 69 71 73 75 75 78 81 84 71 73 75 78 78 81 84 87 75 75 78 81 81 84 87 90 78 78 81 84 84 87 90 93 81 81 84 87 87 90 93 96 84 84 87 90 90 93 96 99 87 87 90 93 93 96 99 102 90 90 93 96 96 99 102 105 93 93 96 99 99 102 105 105 LIQUID LINE PRESSURE GAINS (PSI) For example, using a 3/4 inch suction line on a 3 ton system with 100 feet of total equivalent line length would result in a pressure drop of 7 psi, which is equivalent to a 7% decrease in capacity. Using a 7/8 inch suction line on the same system would result in a pressure drop of 3 psi. NOTE: Horizontal suction lines (for cooling only units) should be pitched at least 1 inch every 20 feet in the direction of the cooling cycle refrigerant flow to aid the return of oil to the compressor. Elevation Limit 50 feet 125 feet 150 feet COOLING CYCLE When the outdoor unit is above the indoor unit, the static pressure gain in the liquid line vertical drop (1/2 psi per foot) may overcome the frictional pressure loss resulting in a total pressure gain. A pressure gain in the liquid line is not detrimental to the performance of the system, but it could cause an overfeeding of the indoor coil which could effect the reliability. This problem can be overcome by using a TXV or decreasing the size of the orifice device. Table 3 shows orifice corrections for various ranges of pressure gain. Friction losses can be calculated using Table 4, which shows pressure drop per 100 feet for various liquid line sizes. Static pressure gain can be calculated at 1/2 psi per foot of drop. Example: Given a 2 ton system with a #55 orifice, 5/16 liquid line, total equivalent piping length of 48 feet and 34 feet of liquid line drop. Friction loss Static gain = 48 ft. x 12.5 psi/100 ft. = 34 ft. x 1/2 psi/ft. Net gain = --6.0 psi = 17.0 psi = 11.0 psi From Table 3, decrease orifice from #55 to #53. On cooling only systems where the outdoor unit is located high above the indoor coil, it may even be possible to reduce the size of the liquid line. The static gain in the vertical drop will offset the increased friction loss caused by smaller tubing. In addition, the reduction in the total system charge due to the smaller liquid line will enhance the reliability of the system. However, as noted previously, never change the liquid line size on heat pumps. With this configuration, gas velocity in the vapor riser must be kept above 1000 feet per minute for R-22 and R-407C, 1250 FPM for R-410A, oil return and below 3000 feet per minute to avoid noise and vibration problems. Table 5 shows friction losses and refrigerant gas velocities for various size vapor lines on each unit size. This table should be used to size vapor lines for proper oil return and minimum pressure loss. NOTE: For either heat pump or cooling only systems in this 1. 2. 3. 4 Unit Size 012 to 060 012 to 018 024 to 060 configuration with elevation differences greater than 3 feet, install traps in the suction riser using the following guidelines: For lifts up to 50 feet, only one trap at the bottom of the riser is required. For lifts between 50 and 100 feet, install a second trap halfway up the riser. For lifts over 100 feet, install traps at 1/3 intervals. Unitary Products Group 036-61920-001 Rev. C (502) Suction Lines Table 4: Refrigerant R-22 (105° F Condensing and 40°F Saturated Evaporator) (Typical Flow Rates) 1674 1042 Pressure drop 100 Ft. 5.9 1.9 Capacity Loss BTUH 777 249 0.0016 0.0024 1565 1048 3.9 1.5 775 296 0.039 0.058 5/8 3/4 0.0016 0.0024 2080 1398 6.6 2.5 1741 662 0.039 0.058 7.5 5/8 3/4 7/8 0.0016 0.0024 0.0033 2581 1729 1244 9.1 3.4 1.6 3266 1240 562 0.039 0.058 0.082 3 9 5/8 3/4 7/8 0.0016 0.0024 0.0033 3095 2072 1492 12.6 4.8 2.2 5454 2068 936 0.039 0.058 0.082 3.5 10.5 3/4 7/8 1 1/8 0.0024 0.0033 0.0057 2418 1741 1021 6.3 2.9 .8 3196 1444 399 0.058 0.082 0.158 4 12 3/4 7/8 1 1/8 0.0024 0.0033 0.0057 2765 1990 1167 8.1 3.6 1 4663 2105 581 0.058 0.082 0.158 5 15 7/8 1 1/8 0.0033 0.0057 2487 1458 5.5 1.5 3951 1088 0.082 0.158 7.5 22.5 1 1/8 1 3/8 1 5/8 0.0057 0.0087 0.0123 2188 1437 1015 3.2 1.1 .5 3421 1237 535 .9# 1.4# 1.9# 10 30 1 3/8 1 5/8 2 1/8 0.0087 0.0123 0.0215 1916 1354 778 1.9 .8 .2 2789 1204 317 1.4# 1.9# 3.3# 12.5 37.5 1 1/8 1 3/8 1 5/8 2 1/8 0.0057 0.0087 0.0123 0.0215 2421 1710 983 3.2 1.4 .4 5251 2263 594 1.4# 1.9# 3.3# 15 45 1 3/8 1 5/8 2 1/8 0.0087 0.0123 0.0215 2873 2030 1167 4.1 1.8 .5 8813 3792 993 1.4# 1.9# 3.3# 20 60 1 3/8 1 5/8 2 1/8 0.0087 0.0123 0.0215 3832 2707 1556 6.9 3 3.3 20017 8593 2243 1.4# 1.9# 3.3# 25 75 1 5/8 2 1/8 0.0123 0.0215 3384 1945 4.5 1.2 16325 4226 1.9# 3.3# Tons of AC Flow Rate Lbs/Min. Type L tubing OD Area SQ. Ft. Velocity FPM 1 3 1/2 5/8 0.001 0.0016 1.5 4.5 5/8 3/4 2 6 2.5 Unitary Products Group R22 oz. Ft. R22- #’s per 100 ft. 0.024 0.039 5 036-61920-001 Rev. C (502) Liquid Lines Table 5: Refrigerant R-22 (105 F Condensing and 40 F Saturated Evaporator) (Typical Flow Rates) Tons of AC Flow Rate Lbs/Min 1 3 6 Type L tubing OD 1/4 5/16 181 106 Press. Drop PSI/100' 10 2.8 Velocity FPM OZs Refrigerant Lbs Refrigerant per foot per 100 ft 0.22 0.38 1.5 4.5 1/4 5/16 3/8 272 160 99 20.3 5.7 1.8 0.22 0.38 0.62 2 6 5/16 3/8 213 132 9.5 3 0.38 0.62 2.5 7.5 5/16 3/8 1/2 266 165 88 14 4.5 1 0.38 0.62 1.15 3 9 5/16 3/8 1/2 319 198 106 19.4 6.2 1.4 0.38 0.62 1.15 3.5 10.5 3/8 1/2 231 124 8.1 1.8 0.62 1.15 4 12 3/8 1/2 263 141 10.3 2.3 0.62 1.15 5 15 3/8 1/2 5/8 329 177 110 15.3 3.5 1.1 0.62 1.15 1.86 7.5 22.5 1/2 5/8 3/4 265 165 111 7.1 2.3 .9 7.2 11.6 17.4 10 30 1/2 5/8 3/4 354 220 147 11.9 3.8 1.5 7.2 11.6 17.4 12.5 37.5 5/8 3/4 275 184 5.7 2.2 11.6 17.4 15 45 5/8 3/4 7/8 330 211 159 7.9 3 1.4 11.6 17.4 24.1 20 60 5/8 3/4 7/8 440 295 212 13.2 5 2.3 11.6 17.4 24.1 25 75 3/4 7/8 1 1/8 368 265 156 7.5 3.4 1 17.4 24.1 41.1 Unitary Products Group 036-61920-001 Rev. C (502) Suction Lines Table 6: Refrigerant R-410A (105° F Condensing and 40°F Saturated Evaporator) (Typical Flow Rates) 1 Flow Rate Lbs/Min. 3 Type L tubing OD 1/2 5/8 1.5 4.5 2 6 2.5 0.001 0.0016 Velocity FPM 1161 726 5/8 3/4 0.0016 0.0024 1085 726 2.5 1 345 131 0.064 0.08 5/8 3/4 0.0016 0.0024 1449 970 4.3 1.6 776 295 0.064 0.08 7.5 5/8 3/4 7/8 0.0016 0.0024 0.0033 1810 1212 873 6.4 2.4 1.7 1453 552 250 0.064 0.08 0.128 3 9 5/8 3/4 7/8 0.0016 0.0024 0.0033 2172 1454 1047 9 3.4 1.5 2430 921 417 0.064 0.08 0.128 3.5 10.5 3/4 7/8 1 1/8 0.0024 0.0033 0.0057 1696 1221 716 4.5 2 0.6 1422 643 178 0.08 0.128 0.208 4 12 3/4 7/8 1 1/8 0.0024 0.0033 0.0057 1939 1395 818 5.7 2.6 0.7 2074 936 259 0.08 0.128 0.208 5 15 7/8 1 1/8 0.0033 0.0057 1744 1023 3.9 1.1 1758 484 0.128 0.208 6.3 19.1 7/8 1 1/8 0.0033 0.0057 2197 1289 5.9 1.6 3382 929 0.8 1.3 7.5 22.5 1 1/8 1 3/8 1 5/8 0.0057 0.0087 0.0123 1535 1008 712 2.2 0.8 0.4 1522 550 238 1.3 2 2.8 10 30 1 1/8 1 3/8 1 5/8 0.0057 0.0087 0.0123 2046 1344 949 3.8 1.4 0.6 3440 1241 536 1.3 2 2.8 12.5 37.5 1 1/8 1 3/8 1 5/8 0.0057 0.0087 0.0123 2558 1680 1187 5.7 2.1 .9 6491 2336 1007 1.3 2 2.8 15 45 1 3/8 1 5/8 2 1/8 0.009 0.0123 0.0215 2015 1424 818 2.9 1.2 .3 3920 1687 442 2 2.8 4.8 20 60 1 3/8 1 5/8 2 1/8 0.009 0.0123 0.0215 2687 1898 1091 4.9 2.1 .6 8902 3822 998 2 2.8 4.8 25 75 1 5/8 2 1/8 0.0123 0.0215 2373 1364 3.2 .8 7220 1880 2.8 4.8 Tons of AC Unitary Products Group Area Sq. Ft. Pressure Capacity drop 100 Ft. Loss BTUH 3.8 346 1 131 R410A oz. Ft. 0.003 0.064 (#'s R410A per 100 ft.) 7 036-61920-001 Rev. C (502) Liquid Lines Table 7: Refrigerant R-410A (105° F Cond. and 40°F Saturated Evap.) (Typical Flow Rates) Tons of AC Flow Rate Lbs/ Min 1 3 8 Type L tubing OD 1/4 5/16 211 124 Pressure drop 100 FT. 10.9 3 Velocity FPM R410A oz. Ft. R410A-#'s per 100 ft. .19 .34 1.5 4.5 1/4 5/16 3/8 317 186 115 22.2 6.2 2 .19 .34 .54 2 6 5/16 3/8 248 154 10.4 3.3 .34 .54 2.5 7.5 5/16 3/8 1/2 310 192 103 15.4 4.9 1.1 .34 .54 1.00 3 9 5/16 3/8 1/2 372 231 124 21.3 6.6 1.5 .34 .54 1.00 3.5 10.5 3/8 1/2 269 145 8.9 2 .54 1.00 4 12 3/8 1/2 308 165 11.3 2.6 .54 1.00 5 15 3/8 1/2 5/8 385 206 129 16.9 3.8 1.2 .54 1.00 1.85 7.5 22.5 1/2 5/8 3/4 310 193 129 7.8 2.5 1 6.3 10 15 10 30 1/2 5/8 3/4 354 220 147 11.9 3.8 1.5 7.2 11.6 17.4 12.5 37.5 5/8 3/4 275 184 5.7 2.7 11.6 17.4 15 45 5/8 3/4 7/8 330 221 159 7.9 3 1.4 11.6 17.4 24.1 20 60 5/8 3/4 7/8 440 295 212 13.2 5 2.3 11.6 17.4 24.1 25 75 3/4 7/8 1 1/8 368 265 156 7.5 3.4 1 17.4 24.1 41.1 3.4 6.3 10 Unitary Products Group 036-61920-001 Rev. C (502) Suction Lines Table 8: Refrigerant R-407C (105°F Cond. and 40°F Saturated Evap.) 7.5 22.5 1 1/8 1 3/8 1 5/8 0.0057 0.0087 0.0123 2188 1437 1015 3.2 1.1 .5 3421 1237 535 R407C #'s per100 ft. 0.9 1.4 1.9 10 30 1 3/8 1 5/8 2 1/8 0.0087 0.0123 0.0215 1916 1354 778 1.9 .8 .2 2789 1204 317 1.4 1.9 3.3 12.5 37.5 1 1/8 1 3/8 1 5/8 2 1/8 0.0057 0.0087 0.0123 0.0215 3648 2395 1692 973 8.1 2.9 1.9 .3 14595 5251 2263 594 0.9 1.4 1.9 3.3 15 45 1 3/8 1 5/8 2 1/8 0.0087 0.0123 0.0215 2873 2030 1167 4.1 1.8 .5 8813 3792 993 1.4 1.9 3.3 20 60 1 3/8 1 5/8 2 1/8 0.0087 0.0123 0.0215 3832 2707 1556 6.9 3 .8 20017 8593 2243 1.4 1.9 3.3 75 1 5/8 2 1/8 2 5/8 0.0123 0.0215 0.033 3384 1945 1261 4.5 1.2 0.4 16235 4226 1479 1.9 3.3 5.1 Tons of AC Flow Rate Lbs/ Type L tubing Min OD 25 Area SQ. Ft. Velocity FPM Pressure drop Capacity Loss 100 ft. BTUH Liquid Lines Table 9: Refrigerant R-407C (105° F Cond. and 40°F Saturated Evap.) (Typical Flow Rates) 283 176 118 Pressure drop 100 FT. 7.6 2.4 .9 R407C-#'s per 100 ft. 6.8 11 16.4 1/2 5/8 3.4 377 235 157 12.6 4.1 1.6 6.8 11 16.4 37.5 5/8 3/4 293 196 6 2.3 11 16.4 15 45 5/8 3/4 7/8 352 236 170 8.4 3.2 1.5 11 16.4 22.7 20 60 5/8 3/4 7/8 469 314 226 14.1 5.4 2.4 11 16.4 22.7 25 75 3/4 7/8 1 1/8 393 283 166 8 3.6 1 16.4 22.7 38.8 Tons of AC Flow Rate Lbs/Min Type L tubing OD Velocity FPM 7.5 22.5 1/2 5/8 3/4 10 30 12.5 Unitary Products Group 9 036-61920-001 Rev. C (502) HEATING CYCLE (Heat Pumps Only) In the heating mode, liquid will travel from the indoor unit up the liquid riser to the outdoor unit. This will result in a liquid line pressure drop and a starved outdoor coil. Since heat pumps have a defrost cycle, coil freeze--up is not a problem. However, the resulting lower suction pressure will decrease the capacity and efficiency of the system. Figures 4 thru 7 are curves which show the heating and efficiency losses for elevation differences at various outdoor ambients. There is nothing that can be done to correct this problem since line sizes cannot be changed on heat pumps and capillary tubes are used for expansion at the outdoor coil. Fortunately, all capacity and efficiency losses decrease as the outdoor ambient decreases, which is advantageous to the heat pump system performance. The third application is using a sweat connect unit with field supplied tubing. Remember, all sweat connect units are shipped from the factory with enough refrigerant for the first (15 or 25) feet of standard size piping. (See installation instructions for proper charge included in unit.) The charge requirement for the vapor and liquid lines can be determined by multiplying the total line length in excess of the factory line charge by each of the appropriate factors from Table 6. Example: For a 3 ton sweat--connect system using a 3/8 liquid line and a 3/4 vapor line and having 50 total measured feet of piping. (35 ft. greater than factory line charge of 15 ft.) Liquid line charge add = 35 ft. x 0.62 oz./ft. = 21.7 oz. Vapor line charge add = 35 ft. x 0.06 oz./ft. = 2.1 oz. 23.8 oz. (round to 24 oz.) ADDITIONAL REFRIGERANT In many applications, additional refrigerant will have to be added to the system. The actual amount of charge that must be added is determined by adding the following: 1. The indoor coil charge adjustment from the Product Tech Guide. This is always a predetermined amount based on the outdoor unit/indoor coil combination being used. 2. The additional charge required for the interconnecting piping. This is dependent on the type of unit being used (i.e., sweat or quick--connect) and the size of the vapor and liquid lines. There are three possible applications for the interconnecting tubing, each of which requires a different amount of additional charge. These three applications are explained below. The first and easiest combination is using a unit with quick-connects and factory--supplied pre--charged line sets. This combination does not require any additional refrigerant for the interconnecting tubing. The only additional charge required is that for the indoor coil adjustment. The second application is using a quick--connect unit with stub kits and field supplied tubing. The additional charge requirement can be determined by multiplying the total measured line length of the vapor and liquid lines by the appropriate factors from Table 6. Example: For a system using a 3/8 liquid line and a 3/4 suction line with a total measured length of 50 feet, Liquid line 50 feet x 0.62 oz./foot Suction line 50 feet x 0.06 oz./foot Charge add for interconnecting tubing = = = 31 oz. 3 oz. 34 oz. Table 10: Line Charge SUCTION 1/2 5/8 3/4 7/8 1-1/8 10 R-22 LINE CHARGE 0Z./FT. LIQUID 0.02 1/4 0.04 5/16 0.06 3/8 0.08 1/2 0.14 ADDITIONAL REQUIREMENTS If not provided as standard features, the following items are required when measured piping lengths exceed fifty (50) feet: 1. Low Voltage Start Kit (2SA06701006) -- single phase units on 208V application. 2. Off Cycle Timer (2TD08700124) -- if item 1 is used. 3. Crankcase Heater (025--19961--001) -- except units with a scroll compressor. On cooling only systems with measured piping lengths greater than seventy--five (75) feet, one of the accumulators in Table 7 must be field installed near the outdoor unit. The accumulator should be sized based on total system charge. The total system charge is determined by adding the outdoor unit charge and the indoor coil adjustment from the Product Tech Guide and the additional charge required for the interconnecting piping. NOTE: If underground piping runs exceed 10 feet, an accumulator must be installed. Example 1 Given a 3 ton heat pump with a 208V application using sweat connections and factory supplied crankcase heater. Assume the orifice required for this system is a #69 and the additional charge from the tech guide orifice chart is 4 oz. Total equivalent vapor line length is 75 feet plus one long radius elbow and two 90° short radius elbows for trap. Total equivalent liquid line length is 75 feet plus two long radius elbows. 3/4" Vapor line = 75 ft. + 1 ells (1.4 ft.) + 2 ells (1.6 ft) = 79.6 ft. 7/8" Vapor line = 75 ft. + 1 ells (1.6 ft.) + 2 ells (1.8 ft) = 80.2 ft. 5/16" Liquid line = 75 ft. + 2 ells (.5 ft.) = 76.0 ft. OZ./FT. 0.23 0.40 0.62 1.12 Vapor Line --. The factory supplied vapor connection on a 3 ton unit is 3/4. From Table 5, a 3/4 vapor line will result in a 5.6 psi pressure drop (79.6 ft. x 7 psi/100 ft.). The vapor line may be increased one size on heat pumps, therefore, using a 7/8 line will result in a 2.4 psi pressure drop (80.2 ft. x 3 psi/ 100 ft.). The gas velocity for the 7/8 line is 1770 ft./min., which is adequate for oil return. Unitary Products Group 036-61920-001 Rev. C (502) Liquid Line --. Liquid lines on heat pumps must match the standard factory supplied fitting. In this example, the liquid line must be 5/16. Orifice Change -- From Table 4, the liquid line pressure change is: Friction loss Static gain = 76.4 ft. x 26 psi/100 ft. = 50 ft. x 0.5 psi/ft. Net gain of = --19.9 psi = 25.0 psi = 5.1 psi Suction line --. The factory supplied suction connection on a 3 ton unit is 3/4. From Table 5, a 3/4 suction line will result in a 4.4 psi pressure drop (62.8 ft. x 7 psi/100 ft.). Increasing the suction line to 7/8 will result in a 1.9 psi pressure drop (63.2 ft. x 3 psi/100 ft.). Choosing the 7/8 suction line will minimize capacity loss. Liquid line --. The factory supplied liquid connection is 5/16. However, from Table 2, a 3 ton unit with a 5/16 liquid line and a total equivalent line length between 50 and 75 feet is allowed only 21 feet of lift. A 3/8 liquid line is allowed 45 feet of lift. Therefore, the 3/8 liquid line must be used. Orifice change -- . From Table 4, the liquid line pressure change is: From Table 3, no change to the orifice is required. Additional Charge --. Using a 3/8 liquid line and 7/8 suc- Friction loss= 61.6 ft. x 9.7 psi/100 ft.= --6.0 psi Static loss= 35 ft. x 0.5 psi/ft.= --17.5 psi Net loss of = --23.5 psi tion line, from Table 6, the additional charge required for the 60' beyond the 15' factory charge allowance is calculated as follows: Additional charge from tech guide orifice chart Liquid line Vapor line 75 ft. x 0.40 oz./ft. 75 ft. x 0.08 oz./ft. = 4 oz. = 37 oz. = 5 oz. 46 oz. Heat Cycle Capacity and Efficiency Losses -- . From Figure 7,heating cycle capacity and efficiency losses resulting from the 50 ft. elevation difference are as follows: Additional Requirements -- . Since the total piping length exceeds 50 feet, the following items must be field installed if not provided as standard factory equipment: Low voltage start kit Off cycle timer Crankcase heat is factory supplied. Example 2 Given a 3 ton cooling system with a 208V application using quick connects and stub kits. No crankcase heater supplied. Assume the orifice required for this system is a #73 and the additional charge from the tech guide orifice chart is 4 oz. Total equivalent line length is 60 feet plus two long radius elbows. From Table 3, the required orifice for this system is #78. Additional Charge --. Using a 3/8 liquid line and a 7/8 suction line, from Table 6, the additional charge required is calculated as follows: Additional charge from tech guide orifice chart Liquid line Suction 60 ft. x 0.62 oz./ft. 60 ft. x 0.08 oz./ft. = 4.0 oz. = 37.2 oz. = 4.8 oz. 46.0 oz. Additional Requirements -- . Since the total piping length exceeds 50 feet, the following items must be field installed if not provided as standard factory equipment: • Low voltage start kit • Off cycle timer • Crankcase heater 3/4" Suction line = 60 ft + 1 ells (1.4 ft.) + 2 ells (1.6 ft) = 64.6 ft. 7/8" Suction line = 60 ft + 1 ells (1.6 ft.) + 2 ells (1.8 ft.) = 65.2 ft. 3/8" Liquid line = 60 ft + 2 ells (.5 ft.) = 61.0 ft. Unitary Products Group 11 036-61920-001 Rev. C (502) EXAMPLE 3 - 20 TON REFRIGERATION PIPING FIGURE 27: 20 TON REFRIGERATION PIPING To put the guidelines in the piping manual to practical application, we'll use the example above to size the suction and liquid refrigeration lines. The unit is a 20 ton split unit with 2 stages of cooling operation, or 50% capacity reduction. Our measured line length is 150 feet. Note that our example shows a single suction and single liquid line. The new 20 ton condensing unit would require two suction and liquid lines, one set for each circuit. Sizing would be identical for each set of lines. SUCTION LINE - Based on a pressure drop of 1.9 PSI per 100' at 10 tons of capacity, we've chosen a 1 3/8" O.D. copper line to begin our calculations. Our example shows a single suction riser, 38 feet in length. With a riser greater than 3 feet, we must add a trap. The trap consists of (2) 45° elbows and (1) 90° elbow. For equivalent length purposes, two 45° elbows equal one 90° elbow. This is a total of 5 elbows (2 short, three long radius) in the suction line. Rounded to the next highest whole foot, this adds 13 feet of equivalent length (see the fitting loss table for length per fitting) to our measured length of 150 feet, for a total equivalent length of 163 feet. of a pound pressure drop should not be a problem. If you suspect the unit is very closely matched to the load, you should consider using the next higher line size. The velocity of 1916 fpm is well within our 1000 FPM minimum and 3000 FPM maximum. LIQUID LINE - In our example above, the liquid line shows both a liquid rise (57') and a liquid fall (38'). If we subtract the fall from the rise, this leaves us with a net rise of 19' or a pressure loss of 9.5 lbs. The pressure drop in 5/8" O.D. copper pipe at 10.0 tons is 3.8 lbs for 100' of line. Our measured length is 150', so we have a pressure drop due to friction of 5.7 pounds. Four 5/8" long radius elbows have an equivalent length of 1.3' per elbow, adding 5 feet of equivalent length. Our system has a liquid line dryer (2 lbs), a sight glass (2 lbs) and a solenoid valve (3 lbs). Adding the numbers shows a calculated total pressure drop in our line is 27.2 pounds. Based on our above calculations, the suction line would be 1 3/8" and the liquid line would be 5/8". The pressure drop in 163 feet of 1 3/8" O.D. copper is 3.097 psi. This is slightly over our 3 psi recommended maximum, however if capacity loss is not an issue, the additional tenth 12 Unitary Products Group 036-61920-001 Rev. C (502) PIPING GUIDE WORKSHEET SPLIT SYSTEM AIR CONDITIONERS AND HEAT PUMPS Project Name: ___________________________ Project Date: ___/___/___ (Must be used with 036-61920-001) LIQUID LINE WORKSHEET Unit Model_____________________________ Unit Size ____________ Tons Rated Capacity ____________ BTU/HR Coil Model _____________________ Orifice Size For Coil Match ____________ Orifice Size Shipped In Coil ____________ Charge Adder For Coil Selection_____________OZS. Does Liquid Flow Up A Vertical Riser? q Yes q No Standard Line Size (Choice 1) (Choice 2) O.D. O.D. PSI/100 FT. PSI/100 FT. 3. From Tables, list the refrigerant charge per foot. OZ./FT. OZ./FT. 4. Divide line 2 by 100 (pressure drop per foot). PSI/FT. PSI/FT. FT. FT. 1. From Tables, pick two liquid lines. NOTE: Standard line size only on heat pump. 2. From Tables, list the friction loss for each. 5. Measure the lineal feet of liquid line. 6. From Tables, find the equivalent length of fittings. fittings x equivalent length FT. fittings x equivalent length FT. fittings x equivalent length FT. fittings x equivalent length FT. 7. Total equivalent length (line 5 plus section 6). FT. FT. 8. Multiply line 7 x line 4 to determine pressure loss due to friction. PSI PSI 9. Is there a sight glass? If yes, add 1 psi. NOTE: No external drier PSI PSI PSI PSI PSI PSI OZ. OZ. is required since one is factory installed in every outdoor unit. 10. Measure vertical riser(s). NOTE: Liquid flowing up riser equals pressure loss. Liquid flowing down riser equals pressure gain. If you have both lift and drop, subtract drop feet from lift feet. Multiply lineal feet ____________FT. x .5 psi/ft. to determine pressure loss (or gain) due to static head. 11. Total line 8 + line 9 + line 10 to determine total pressure loss or gain Do not exceed 30 psig pressure loss. 12. Orifice size based on pressure loss or gain. See Table 3. 13. Refrigerant charge total ounces for liquid line. (multiply line 5 x line 3) Unitary Products Group 15 036-61920-001 Rev. C (502) SUCTION LINE WORKSHEET Unit Model_____________________________ Unit Size ____________ Tons Rated Capacity ____________ BTU/HR Coil Model _____________________ Suction Gas Flows Up A Vertical Riser?_____________________________________ q Yes How Many? ________________________ Is A Suction Trap Required? q No Standard Line Size (Choice 1) 1. From Tables, pick two suction lines. (Choice 2) O.D. O.D. FT./MIN. FT./MIN. PSI/100 FT. PSI/100 FT. 4. From Tables, list the refrigerant charge per foot. OZ./FT. OZ./FT. 5. Divide line 3 by 100 (pressure drop per foot). PSI/FT. PSI/FT. FT. FT. 2. From Tables, list the velocity of each choice. 3. From Tables, list the friction loss for each choice. 6. Total measured length of suction line. 7. From Tables, find the equivalent length of fittings. fittings x equivalent length FT. fittings x equivalent length FT. fittings x equivalent length FT. fittings x equivalent length FT. 8. Total equivalent length (line 6 + section 7). FT. FT. PSI PSI BTU/HR. BTU/HR. 9. Multiply line 8 and line 5 to determine pressure loss due to friction. (Should not exceed 3 psi) a. If line 9 exceeds 3 psi determine capacity loss. (line 9 x 1%/psi x rated capacity). 10. System refrigerant Suction line charge total ounces line 4 times line 6. OZS. 11. Liquid line charge (item 13 from Liquid Line Worksheet, see page 1). OZS. 12. Additional system charge (add line 10 plus line 11 plus charge adder for coil). OZS. NOTE: If unit is sweat connect, subtract amount in Tables. q Yes, q No. 13. Is an accumulator required? (greater than 75 feet total line length or underground piping longer than 10 feet) a. If yes, calculate total system charge. (add line 12 plus unit nameplate charge) OZS. NOTE: 1 lb. of refrigerant equals 16 ozs. b. Select accumulator from Tables based on charge determined in Item 13a. Part No. Additional requirements may be necessary for line lengths beyond fifty (50) 14. feet. a. Low Voltage Start Kit (if single phase 208 volt network) q Yes, q No. b. Off Cycle Timer (required if Item 14a is used) q Yes, q No. c. Crankcase Heater (if not already supplied in unit) q Yes, q No. Summary: Project Requires Liquid Line Size _____________________ 14 Suction Line Size ______ Orifice Size ________ Additional System Charge _______ Unitary Products Group 036-61920-001 Rev. C (502) COMMERCIAL SUCTION LINE WORKSHEET DATE__________ JOB NAME_____________________ CALCULATED BY____________________ Unit tonnage_______ Highest tonnage per circuit________ Lowest tonnage per circuit_______ Are there any suction risers greater than 3 feet?(Y/N)_____ If so, how many?________ 1. List two possible line sizes O.D. 2. List the refrigerant charge for each foot of line lb/ft. 3. List velocity at lowest tonnage fpm Min. horizontal velocity is 700 fpm for R-22 (or 850 fpm with R-410A) and min. vertical velocity is 1000 fpm for R-22 (or 1350 fpm for R-410A). Use 1 pipe size smaller for the riser than is used for the horizontal run for increased velocity. 4. List velocity at highest tonnage fpm Max. velocity is 3000 fpm 5. List pressure drop per foot of line psi Divide the chart value by 100 6. 6. List the total line length. 7. Calculate the equivalent length of fittings: ft. _____ fittings X _____ feet per fitting ft. _____ fittings X _____ feet per fitting ft. _____ fittings X _____ feet per fitting ft. _____ fittings X _____ feet per fitting ft. 8. Add line 6 and line 7 to get the total equivalent length 9. Multiply line 5 by line 8 ft. psi Pressure drop should not exceed 3 psi. 1psi of pressure drop = 1% capacity loss 10. Multiply line 2 by line 6 lbs. If a downsized vertical riser is required, the calculated pressure drop listed on line 9 will be higher. However, in most applications, the slight decrease in capacity is an acceptable trade-off to insure oil will return to the compressor when the system is running on 1st stage only. Unitary Products Group 15 036-61920-001 Rev. C (502) COMMERCIAL LIQUID LINE WORKSHEET Unit Capacity in tons________ Number Of Refrigeration Circuits________ Circuit Capacity________ 1. List two possible line sizes O.D. 2. List pressure drop per foot of line Divide the chart value by 100 psi/ft. 3. List the refrigerant charge per foot of line lb/ft. 4. List the total line length. 5. List the net length of the liquid riser and drop Circle rise or drop to indicate which is being used. 6. Calculate the equivalent length of elbows: _____ elbows X _____ feet per elbow _____ elbows X _____ feet per elbow ft. ft. ft. 7. Add line 4 and line 6 to get the total equivalent length ft. 8. Multiply line 7 by line 2 psi(-) 9. Multiply line 4 by .5 psi psi(+/-) 10. If line 9 is a riser, subtract it from line 8. If it's a drop, add it to line 8. Remember, line 8 is pressure loss, so it represents a negative number. 11. Add 2 psi for the dryer & sight glass. Add 2 psi if a SV is used. A dryer and sight glass are recommended for every application. 12. Add line 10 and line 11 The total loss on line 12 must not exceed 40psi. (3 psi loss = 1° subcooling loss) 13. Multiply line 3 by line 4 psi(+/-) psi(-) psi(+/-) lbs. 14. List the total suction line charge from line 10 on the opposite page lbs. 15. List the operating charge of the unit found in the I/O or on the unit nameplate If holding charge has not been recovered from the unit, subtract 1 pound from this value. lbs. 16. Add line 13, line 14 and line 15. lbs. Summary: Project Requires Suction Line Size _______________________ 16 Suction Riser Size (If Needed) _______ Unitary Products Group 036-61920-001 Rev. C (502) NOTES: Unitary Products Group 17 NOTES: Subject to change without notice. Printed in U.S.A. Copyright © by York International Corp. 2002. All rights reserved. Unitary Products Group 036-61920-001 Rev. C (502) Supersedes: 690.01-AD1V (1296) 5005 York Drive Norman OK 73069