ADDING OR REMOVING REFRIGERANT
This system uses HFC−410A refrigerant which operates at much higher pressures than HCFC−22. The pre−installed liquid line filter drier is approved for use with HFC−410A only. Do not replace it with components designed for use with HCFC−22.
COOLING MODE INDOOR AIRFLOW CHECK
Check airflow using the Delta−T (DT) process using the illustration in figure 20.
HEATING MODE INDOOR AIRFLOW CHECK
Blower airflow (CFM) may be calculated by energizing electric heat and measuring:
STemperature rise between the return air and supply air temperatures at the indoor coil blower unit,
SMeasuring voltage supplied to the unit,
SMeasuring amperage being drawn by the heat unit(s).
Then, apply the measurements taken in following formula to determine CFM:
Amps x Volts x 3.41
CFM =
1.08 x Temperature rise (F)
AIRFLOWINDOOR COIL |
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| DT |
TEMPERATURE OF AIR |
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| 80 24 24 24 23 23 22 22 22 20 19 18 17 16 15 | ||
ENTERING INDOOR COIL ºF |
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| DRY−BULB | 78 23 23 23 22 22 21 21 20 19 18 17 16 15 14 | |
| 76 22 22 22 21 21 20 19 19 18 17 16 15 14 13 | ||
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| 74 21 21 21 20 19 19 18 17 16 16 15 14 13 12 | |
A |
| 72 20 20 19 18 17 17 16 15 15 14 13 12 11 10 | |
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| 70 19 19 18 18 17 17 16 15 15 14 13 12 11 10 | |
WET−BULB ºF | 57 58 59 60 61 62 63 64 65 66 67 68 69 70 | ||
DRY |
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| B |
BULB |
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C
TDROP
53º | 19º |
AIR FLOW | AIR FLOW |
A
72º
B
64º
All temperatures are expressed in ºF | INDOOR COIL |
DRY BULB
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| WET BULB |
Use the following procedure to adjust for optimal air flow across the indoor coil: | ||||||||
1. DETERMINE THE DESIRED DT |
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| TURE USING DRY BULB (A) AND WET BULB (B). DT IS THE INTERSECTING VALUE | |||||
OF A AND B IN THE TABLE (SEE TRIANGLE). |
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2. Find temperature drop across coil |
| A and C). Temperature Drop Formula: | ||||||
(TDrop) = A minus C. |
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3. Determine if fan needs adjustment | ference between the measured TDrop and the desired DT | |||||||
is needed. See example below: |
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| ASSUME DT = 15 AND A TEMP. = 72º, THESE C TEMPERATURES WOULD NECESSITATE STATED ACTIONS: | |||||
Cº | TDROP | – | DT | = | ºF | ACTION |
| Changing air flow affects all temperatures; recheck temperatures to |
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53º | 19 | – | 15 | = | 4 | INCREASE THE AIRFLOW | confirm that the temperature drop and DT are within +3º. | |
58º | 14 | – | 15 | = | −1 | (WITHIN +3º RANGE) NO CHANGE |
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62º | 10 | – | 15 | = | −5 | DECREASE THE AIRFLOW |
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4.ADJUST THE FAN SPEED
Figure 20. Checking Indoor Airflow over Evaporator Coil using Delta−T Chart Formula
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