Carrier 38HDR - Page 13

13
Subcooling
Method
NOTE: Units are charged at the factory for 15 ft of tubing. Adjust
charge by plus or minus 0.6 oz per foot of tubing greater or less
than 15 ft respectively.
For 38HDR units, the subcooling method is used to check and
adjust charge during the cooling season. Refer to Table 4 and the
following procedure:
1. Operate unit a minimum of 15 minutes before checking
charge.
2. Measure liquid line temperature near liquid line service
valve, and measure the liquid pressure at the liquid line ser-
vice valve. Use a digital thermometer for all temperature
measurements. DO NOT use mercury or dial--type ther-
mometers.
3. Refer to Table 4. Find the temperature point at which the
required subcooling temperature intersects the measured liq-
uid line pressure.
4. If the measured liquid line temperature does not agree with
the required liquid line temperature, ADD refrigerant to
lower the temperature, or REMOVE refrigerant to raise the
temperature (allow a tolerance of ±3_F/1.67_C).
Table 4 —Subcooling Charging Table
LIQUID
PRES-
SURE AT
SERVICE
VAL VE
REQUIRED LIQUID LINE TEMPERATURE
Required Subcooling Temperature
8 10 12 14 16 18
psig _F °C _F °C _F °C _F °C _F °C _F °C
189 58 32 56 31 54 30 52 29 50 28 48 27
195 60 33 58 32 56 31 54 30 52 29 50 28
202 62 34 60 33 58 32 56 31 54 30 52 29
208 64 36 62 34 60 33 58 32 56 31 54 30
215 66 37 64 36 62 34 60 33 58 32 56 31
222 68 38 66 37 64 36 62 34 60 33 58 32
229 70 39 68 38 66 37 64 36 62 34 60 33
236 72 40 70 39 68 38 66 37 64 36 62 34
243 74 41 72 40 70 39 68 38 66 37 64 36
251 76 42 74 41 72 40 70 39 68 38 66 37
259 78 43 76 42 74 41 72 40 70 39 68 38
266 80 44 78 43 76 42 74 41 72 40 70 39
274 82 46 80 44 78 43 76 42 74 41 72 40
283 84 47 82 46 80 44 78 43 76 42 74 41
291 86 48 84 47 82 46 80 44 78 43 76 42
299 88 49 86 48 84 47 82 46 80 44 78 43
308 90 50 88 49 86 48 84 47 82 46 80 44
317 92 51 90 50 88 49 86 48 84 47 82 46
326 94 52 92 51 90 50 88 49 86 48 84 47
335 96 53 94 52 92 51 90 50 88 49 86 48
345 98 54 96 53 94 52 92 51 90 50 88 49
354 100 56 98 54 96 53 94 52 92 51 90 50
364 102 57 100 56 98 54 96 53 94 52 92 51
374 104 58 102 57 100 56 98 54 96 53 94 52
384 106 59 104 58 102 57 100 56 98 54 96 53
395 108 60 106 59 104 58 102 57 100 56 98 54
406 110 61 108 60 106 59 104 58 102 57 100 56
416 112 62 110 61 108 60 106 59 104 58 102 57
427 114 63 112 62 110 61 108 60 106 59 104 58
439 116 64 114 63 112 62 110 61 108 60 106 59
450 118 66 116 64 114 63 112 62 110 61 108 60
462 120 67 118 66 116 64 114 63 112 62 110 61
474 122 68 120 67 118 66 116 64 114 63 112 62
486 124 69 122 68 120 67 118 66 116 64 114 63
499 126 70 124 69 122 68 120 67 118 66 116 64
511 128 71 126 70 124 69 122 68 120 67 118 66
38HDR