3DJH
The Subcooling Method
TXV Systems, < 60EF Outdoor Temp
Because the outdoor ambient temperature is below
60EF, airflow over the outdoor coil will need to be re-
duced to drive up the liquid line pressure to a range of
200 -- 250 psig. To do this block off the outdoor coil
with cardboard or a plastic sheet.
BLOCKING OUTDOOR COIL
CARDBOARD OR
PLASTIC SHEET
OUTDOOR COIL SHOULD
BE BLOCKED ONE SIDE
AT A TIME WITH CARD--
BOARD OR PLASTIC
SHEET UNTIL PROPER
TESTING PRESSURES
ARE REACHED.
FIGURE 8
1-- Remove the cap from the liquid line service valve
stem and turn the stem clockwise 1/4 to 1/2 turn.
This will open the service port. Exercise caution--
the service port is not equipped with a valve core.
2-- With the manifold gauge hose still on the liquid
service port and the unit operating, read the liquid
line pressure.
3-- If the pressure is too low, block the airflow
through the outdoor coil until the liquid line pres-
sure stabilizes in a range of 200 to 250 psig. At that
time, record the liquid line temperature and the
liquid line pressure reading.
4-- Using a temperature/pressure chart for R22, de-
termine the saturation temperature for the liquid
line pressure reading.
5-- Subtract the liquid line temperature from the sat-
uration temperature (according to the chart) to
determine Subcooling. (Liquid line temperature --
Saturation temperature = Subcooiling)
6-- Compare the Subcooling value with those in table
4. If Subcooling is greater than shown, refrigerant
must be reclaimed. If Subcooling is less than
shown, refrigerant must be added.
TABLE 4
SUBCOOLING TEMP. (EF)
MODEL
HP23--211
HP23--410
HP23--460
4 + 2
HP23--311
HP23--261
HP23--141
HP23--510
HP23--650
SUBCOOLING METHOD--TXV Systems
9 + 2
13 + 2
9 + 2
9 + 2
8 + 2
6 + 2
7 + 2
HP23--410CDN
13 + 2
The Approach Method
TXV Systems, > 60EF Outdoor Temp
+DYLQJ WDNHQ WKH RXWGRRU DPELHQW DQG OLTXLG OLQH WHPSHUD
WXUH UHDGLQJV VXEWUDFW WKH RXWGRRU DPELHQW WHPSHUDWXUH
IURP WKH OLTXLG OLQH WHPSHUDWXUH WR GHWHUPLQH WKH $S
SURDFK WHPSHUDWXUH /LTXLG OLQH E) 2XWGRRU $PELHQW
E) $SSURDFK WHPSHUDWXUH 7KH UHVXOWLQJ GLIIHUHQFH
$SSURDFK WHPSHUDWXUH VKRXOG DJUHH ZLWK WKH YDOXHV JLY
HQ LQ WDEOH ,I QRW DGG UHIULJHUDQW WR ORZHU WKH DSSURDFK
WHPSHUDWXUH RU UHFRYHU UHIULJHUDQW IURP WKH V\VWHP WR LQ
FUHDVH WKH DSSURDFK WHPSHUDWXUH
TABLE 5
HP23--211
HP23--410CDN
HP23--460
6
14
12
HP23--311/410
7
HP23--261
5
HP23--141
HP23--510
HP23--650
11
7
11
APPROACH METHOD
MODEL NO.
APPROACH TEMPERATURE
LIQUID LINE E F
-- OUTDOOR AMBIENT E F
Note--For best results, the same thermometer should be used to
check both outdoor ambient and liquid temperatures.
6<67(0 23(5$7,21
Compressor Oil Charge
Refer to Lennox Cooling Service Handbook for cor-
rect procedure to check and add compressor oil. Heat
pump grade mineral oil (brand and viscosity unspeci-
fied) should be used. See table 6.
&2035(6625 2,/ &+$5*(
7$%/(
81,7 02'(/ 12
&2035(6625 2,/ &+$5*(
)OXLG 2]V
+3
+3
+3
+3
+3
+3
+3
+3
+3 &'1
Filter Drier
The filter drier is equipped with an internal check
valve for correct refrigerant flow. See figure 7. If re-
placement is necessary, order another of like design
and capacity. A strainer in the liquid line gives addi-
tional protection.
