Figure 13
1.Connect the manifold gauge set to the service valve ports as follows (See Figure 13 above):
•Low pressure gauge to suction line service valve
•High pressure gauge to liquid line service valve
2.Close manifold gauge set valves. Connect the center manifold hose to an upright cylinder of R410A.
3.If room temperature is below 70°F, set the room thermostat to call for heat. This will create the necessary load for properly charging the system in the cooling cycle.
4.Use a digital thermometer to record the outdoor ambient temperature.
5.When the heating demand has been satisfied, switch the thermostat to cooling mode with a set point of 68°F. When pressures have stabilized, use a digital thermometer to record the liquid and suction line temperatures.
6.The outdoor temperature will determine which charging method to use. Proceed with the appropriate charging method.
Charge Using
If the system is void of refrigerant, or if the outdoor ambient temperature is cool, use the
1. Recover the refrigerant from the unit.
2.Conduct a leak check, then evacuate as previously outlined.
3.Weigh in the charge according to the total amount shown on the unit nameplate.
If weighing facilities are not available or if unit is being charged during warm weather, use one of the following procedures.
Charge Using Subcooling Method (Fixed Orifice/TXV Systems) - Outdoor Temperatures 65°F or Above
If charging a fixed orifice or TXV system when the outdoor ambient temperature is 65°F or above, the subcooling method can be used to charge the unit.
1.With the manifold gauge hose still on the liquid service port and the unit operating stably, use a digital thermometer to check the liquid line temperature. For best results, use the same digital thermometer to check both the outdoor ambient and the liquid line temperatures.
2.At the same time, record the liquid line pressure reading.
3.Use the temperature/pressure chart (Table 5) to determine the saturation temperature for the liquid line pressure reading.
4.Subtract the liquid line temperature from the saturation temperature (according to the chart) to determine subcooling.
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