21
MAINTENANCE
Let's assume the local gas utility has stated that the calorific
value of the gas is 1,025 BTU per cubic foot.
Multiplying the ninety (90) cubic feet by 1,025 BTU per cubic
foot gives us an input of 92,250 BTUH.
Checking the BTU input on the rating plate of the furnace
being tested.
EXAMPLE:
INPUT:
92,000 BTU/HR
OUTPUT CAP:
84,000
Should the figure you calculated not fall within five (5) percent
of the nameplate rating of the unit, adjust the gas valve
pressure regulator or resize orifices.
CAUTION
Always connect a manometer to the outlet tap at the
gas valve before adjusting the pressure regulator. In
no case should the final manifold pressure vary more
than plus or minus .2 inches water column from 3
inches water column for natural gas.
To adjust the pressure regulator on the gas valve, turn
down (clockwise) to increase pressure and input, and out
(counterclockwise) to decrease pressure and input.
A properly operating unit must have the BTU per hour input
and CFM of air, within the limits shown to prevent short
cycling of the equipment. As the external static pressure
goes up, the temperature rise will also increase. Consult the
proper tables for temperature rise limitation.
Summary of Contents for DM80SE
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