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Heat Controller, Inc. VMH SerieS Installation Manual
Air Purging
Air and moisture in the refrigerant system have undesirable effects as indicated below:
• Pressure in the system rises.
• Operating current rises.
• Cooling or heating efciency drops.
• Moisture in the refrigerant circuit may freeze and block capillary tubing.
• Water may lead to corrosion of parts in the refrigeration system.
Therefore, the indoor unit and tubing between the indoor and outdoor unit must be leak tested and evacuated
to remove any noncondensables and moisture from the system.
Air purging with vacuum pump
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 completed. Remove the service
valve caps from both the gas and the liquid side on the outdoor unit. Note that both the liquid and the
gas side service valves on the outdoor unit are kept closed at this stage.
• Unit charge is located on the rating plate.
• Unit is precharged to include enough refrigerant for 16.5 ft (5m) of line set length per each indoor
unit allowed.
Example: A quad zone 36k outdoor unit will accept up to four indoor units at 16.5 ft (5m) each
for a total factory charge to handle 66 ft (20m) of total line set length.
• Charge adjustment is not required for line set lengths less than 16.5 ft. (5m).
• Add .2 oz./ft. of additional charge for line set lengths above 16.5 (5m) per indoor unit.
• The 12k and 18k indoor units include a line set adaptor for the outdoor section.
Capacity Pipe Size
Btu/H Gas (in.) Liquid (in.)
9k Indoor 3/8” 1/4”
12k Indoor 1/2” 1/4”
18k Indoor 1/2” 1/4”
Standard
Capacity Indoor Unit Length Per Maximum Total Line Length
Btu/h Combination Indoor Unit Elevation Min. Max.
18k Dual Zone (A + B) 16.5 ft. (5m) 32 ft. (10m) 10 ft. (3m) 100 ft. (30.5m)
27k Tri Zone (A + B + C) 16.5 ft. (5m) 32 ft. (10m) 10 ft. (3m) 150 ft. (45m)
36k QuadDual Zone (A + B + C) 16.5 ft. (5m) 32 ft. (10m) 10 ft. (3m) 200 ft. (60m)