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To Test and Adjust Gas (Water Column) Pressure
There are two (2) types of devices commonly used to measure column pressure. They are spring and mechanical-
type gauges and manometers. The spring and mechanical-type gauge is not recommended, because it is easily
damaged and not always accurate. A manometer is simply a glass or transparent plastic tube with a scale in
inches. When filled with water and pressure applied, the water in the tube rises showing the exact water column
pressure.
NOTE: Manometers are available from the factory by ordering ADC P/N 122804.
1. To test gas water column (W.C.) Pressure:
a. Connect water column test gauge connection to gas valve pressure
tap (1/8 NPT). This pressure tap is located on the outlet (manifold)
side of the valve.
b. Start dryer. With burner on, the correct water column reading in
inches would be:
Natural Gas - 3.5 Inches Water Column (8.7 mb).
L.P. Gas - 10.5 Inches Water Column (26.1 mb).
2. To adjust water column pressure (natural gas only, L.P. gas must be
regulated at source):
a. Remove the slotted vent cap on the top of the valve.
b. Turn the slotted adjustment screw located on the top of the valve
next to the terminals. Turn clockwise (CW) to increase manifold
pressure and counterclockwise (CCW) to decrease.
NOTE: If correct W.C. pressure cannot be achieved, problems may be due to an undersized gas supply
line, a faulty or underrated gas meter, etc.
To Convert Natural Gas to L.P. Gas
NOTE: ALL dryers are sold as natural gas, unless otherwise specified at the time the dryer order was
placed. For L.P. gas the dryer must be converted as follows.
1. Refer to Replace Gas Valve and follow Step #1 through Step #6.
a. For models with 3/4 White-Rodgers valve.
1) Remove top vent cap.
2) Insert spring and pin.
3) Replace vent cap.
2. Unscrew main burner orifices and replace with L.P. orifices.
NOTE: Use extreme care when removing orifices. They are made of brass and are easily damaged.