Goodman Mfg R-410A manual Checking Subcooling, Two Speed Application *PH1548**-*PH1560

SERVICING

SUBCOOLING = SAT. LIQUID TEMP. - LIQUID LINE TEMP.

SATURATED LIQUID PRESSURE

TEMPERATURE CHART

Liquid	Saturated Liquid
Pressure	Temperature °F
PSIG	R-410A
200	70
210	73
220	76
225	78
235	80
245	83
255	85
265	88
275	90
285	92
295	95
305	97
325	101
355	108
375	112
405	118

Two Speed Application (*PH1548**-*PH1560**)

Run the unit on low stage cooling for 10 minutes until refriger- ant pressures stabilize. Follow the guidelines and methods below to check unit operation and ensure that the refrigerant charge is within limits. Charge the unit on low stage.

1.Purge gauge lines. Connect service gauge manifold to access fittings. Run system at least 10 minutes to allow pressure to stabilize.

2.Temporarily install thermometer on liquid (small) line near liquid line access fitting with adequate contact and insu- late for best possible reading.

3.Check subcooling and superheat. Two stage systems run- ning on low stage with TXV application should have a subcooling of 5 to 7 ºF and superheat of 15 to 18ºF.

a.If subcooling and superheat are low, adjust TXV to 15 to 18ºF superheat, then check subcooling. NOTE: To adjust superheat, turn the valve stem clockwise to increase and counter clockwise to de- crease.

b.If subcooling is low and superheat is high, add charge to raise subcooling to 5 to 7 ºF then check super- heat.

c.If subcooling and superheat are high, adjust TXV valve to 15 to 18ºF superheat, then check subcooling.

d.If subcooling is high and superheat is low, adjust TXV valve to 15 to 18ºF superheat and remove charge to lower the subcooling to 5 to 7 ºF.

NOTE: Do NOT adjust the charge based on suction pres- sure unless there is a gross undercharge.

4.Disconnect manifold set, installation is complete.

SUBCOOLING = SAT. LIQUID TEMP. - LIQUID LINE TEMP.

Heat Pump - Heating Cycle

The proper method of charging a heat pump in the heat mode is by weighing the charge according to the total charge listed on the rating plate.

S-109 CHECKING SUBCOOLING

Refrigerant liquid is considered subcooled when its tempera- ture is lower than the saturation temperature corresponding to its pressure. The degree of subcooling equals the degrees of temperature decrease below the saturation temperature at the existing pressure.

1.Attach an accurate thermometer or preferably a thermo- couple type temperature tester to the liquid line close to the high pressure access fitting process tube.

2.Install a high side pressure gauge on the high side (liquid) access fitting.

3.Record the gauge pressure and the temperature of the line.

4.Review the technical information manual or specification sheet for the model being serviced to obtain the design subcooling.

5.Compare the hi-pressure reading to the "Required Liquid Line Temperature" chart . Find the hi-pressure value on the left column. Follow that line right to the column under the design subcooling value. Where the two intersect is the required liquid line temperature.

Alternately you can convert the liquid line pressure gauge reading to temperature by finding the gauge reading in Tem- perature - Pressure Chart and reading to the left, find the temperature in the °F. Column.

6.The difference between the thermometer reading and pres- sure to temperature conversion is the amount of subcooling.

Add charge to raise subcooling. Recover charge to lower subcooling.

SUBCOOLING = SAT. LIQUID TEMP. - LIQUID LINE TEMP.

EXAMPLE:

a. Liquid Line Pressure = 417

b. Corresponding Temp. °F. = 120°

c. Thermometer on Liquid line = 113°F.

To obtain the amount of subcooling subtract 113°F from 120°F.

The difference is 7° subcooling, which would fall in the + range of allowable subcooling.

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