Heat Controller DMH18DB-1 manual Air Purging and Evacuation, Checkingmethod, Service Manual

Air Purging and Evacuation

Air Purging and Evacuation

Air and moisture remaining in the refrigerant system have undesirable effects as indicated below.

1.Pressure in the system rises.

2.Operating current rises.

3.Cooling(or heating) efficiency drops.

4.Moisture in the refrigerant circuit may freeze and block capillary tubing.

5.Water may lead to corrosion of parts in the refrigeration system.

Therefore, the indoor/outdoor unit and connecting tube must be checked for leak tight, and vacuumed to remove incondensible gas and moisture in the system.

Checkingmethod

Preparation

•Check that each tube(both liquid and gas side tubes) between the indoor and outdoor units have been properly connected and all wiring for the test run has been complet- ed. Remove the service valve caps from both the gas and the liquid side on the outdoor unit. Check that both the liq- uid and the gas side service valves on the outdoor unit are kept closed at this stage.

Leakage test

1.Do a leakage test of all joints of the tubing(both indoor and outdoor) and both gas and liquid side ser- vice valves.

Bubbles indicate a leak. Be sure to wipe off the soap with a clean cloth.

2.After the system is found to be free of leaks, relieve the nitrogen pressure by loosening the charge hose connector at the nitrogen cylinder. When the system pressure is reduced to normal, disconnect the hose from the cylinder.

• Connect the manifold valve(with pressure gauges) and dry
nitrogen gas cylinder to this service port with charge
hoses.
CAUTION: Be sure to use a manifold
valve for leak testing.			Indoor unit
The high side manifold valve must always
be kept closed.
• Pressurize the system to no more than 150 P.S.I.G.	Outdoor unit
with dry nitrogen gas and close the cylinder valve
when the gauge reading reached 150 P.S.I.G. Next,
test for leaks with liquid soap.
CAUTION: To avoid nitrogen entering the
refrigerant system in a liquid state, the top	Manifold valve
of the cylinder must be higher than its bottom
when you pressurize the system. Usually, the	Pressure	Lo	Hi
cylinder is used in a vertical standing position.	gauge
NOTICE : Leakage test shoud be done for each			Charge hose
indoor unit connection set, separately.
			Nitrogen gas
			cylinder(in vertical
			standing position)
			Service Manual	31