Lennox International Inc Dave Lennox Signature Collection XC17 Air Conditioner Airflow, Action

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. This unit is NOT approved for use with coils which use capillary tubes or fixed orifices as a refrigerant metering device.

Check airflow using the Delta−T (DT) process using the illustration in Figure 12.

AIRFLOW
INDOOR COIL	Dry−bulb	DT
Temperature of air		80 24 24 24 23 23 22 22 22 20 19 18 17 16 15
entering indoor		78 23 23 23 22 22 21 21 20 19 18 17 16 15 14
coil ºF		76 22 22 22 21 21 20 19 19 18 17 16 15 14 13
		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
		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		B
BULB

C TDrop

53º 19º

air flow air flow

A

72º

B

64º

INDOOR COIL

All temperatures are expressed in ºF

DRY BULB

WET BULB

Use the following procedure to adjust for optimal air flow across the indoor coil:
1.	Determine the desired DT	A) and wet bulb (B). DT
	is the intersecting value of A and B in the table (see triangle).
2.	Find temperature drop across coil
	(A and C). Temperature Drop Formula: (TDrop) = A minus C.
3.	Determine if fan needs adjustment ference between the measured	TDrop and the desired
	DT (TDrop–DT) is within +3º, no adjustment is needed. See example below:

Assume DT = 15 and A temp. = 72º, these C temperatures would necessitate stated actions:

Cº	TDrop –		DT	=	ºF	ACTION
53º	19	–	15	=	4	Increase the airflow	Changing air flow affects all temperatures; recheck
				=			temperatures to confirm that the temperature drop
58º	14	–	15		−1	(within +3º range) no change and DT are within +3º.
62º	10	–	15	=	−5	Decrease the airflow

4.Adjust the fan speed

Figure 12. Checking Indoor Airflow over Evaporator Coil using Delta−T Chart

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XC17 SERIES