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It may be necessary to purge the air out of the gas line for initial start-up of the furnace after
installation. This should be done by a qualified heating contractor. If excessive gas escapes
when purging the gas supply at the union, allow the area to ventilate for at least 15 minutes
before attempting to start the furnace. LP gas is especially dangerous because it is heavier
than air and can accumulate to dangerous concentrations at floor level. Heat exchanger oil
will burn off on initial firing creating an unpleasant odor. To prevent this odor from occurring
more than once, open doors and windows and run the blower for at least 30 minutes or until
odor disappears.
The orifice for the burners was sized for either natural gas (having a heating valve of 1025
BTU per cubic foot and a specific gravity of 0.60) or for liquefied propane gas (with a heating
value of 2500 BTU per cubic foot and a specific gravity of 1.53). See the rating plate of your
dehumidifier to determine which type of fuel the heater is configured for.
To verify the actual input of your natural gas burner, proceed as follows:
•
Call your gas supplier and ask for the BTU content (heating value) of one cubic foot of
the gas supplied to the installation area. An alternate approach is to assume a value
of 1025 BTU/ft3, which is the national average.
•
With all other gas appliances turned off, operate the burner for at least ten minutes.
After the equipment has warmed up, use a stop watch to clock the time required for
the small dial on the gas meter to make one full revolution. A label on the meter will
state how many cubic feet have flowed per revolution (usually one, two or five).
Input BTU/hour = (BTU/ft3 x ft3 x 3600 seconds) / (seconds / revolution)
EXAMPLE: (1025 BTU/ft3 x 2 ft3 x 3600) / 74.8 seconds = 98,663 BTU Input
Check for the input of the burner, the type of gas, and the required manifold pressure on the
rating plate located on the exterior of the dehumidifier.
Make sure that the gas supply pressure to the furnace falls within the maximum range of 6" to
14" wc pressure for natural gas and 11.0" to 14.0" wc for LP gas. The pressure to the furnace
must be checked while the furnace burner and any other gas appliances on the same supply
system are operating.
The burners are equipped with fixed orifices sized for the manifold pressure shown on the
rating plate. The input can only be increased or decreased by adjusting the manifold pressure.
Remove the 1/8" threaded pipe plug located on the top right side of the gas valve.
Use a U tube manometer or a pressure gauge to measure the pressure. To adjust the
pressure, remove the screw from the regulator on the outlet side of the gas valve. Turn the
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Desert Aire - QS/QV Manual
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