American Dryer Corp. Phase 6 Microprocessor Controls ML-190HS - Manual (Page 24)

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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
L.P. Gas – 10.5 Inches Water Column
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, problem may be due to an undersized gas
supply line, a faulty or underrated gas meter, etc.
To Convert from 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.
2. Remove the four (4) screws which secure the top cap assembly. This assembly contains the regulator
adjustment screw and the terminal connections.
3. Replace the top cap assembly with the L.P. version.
4. Unscrew main burner orifices and replace with L.P. orifices.
NOTE: Use extreme care when removing and replacing orifices. These orifices are made of brass and
are easily damaged.
5. Reverse the procedure for reinstalling valve assembly to the dryer.
WARNING: Test ALL connections for leaks by brushing on a soapy water solution.
WARNING: NEVER TEST FOR LEAKS WITH A FLAME!!!
NOTE: There is no regulator provided in an L.P. dryer. The column pressure must be regulated at the
source (L.P. tank) or an external regulator must be added to each dryer.