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3 - After allowing the unit to stabilize for ve minutes,
record the manifold pressure.
4 - Disconnect heating demand as soon as an accurate
reading has been obtained.
Proper Gas Flow (Approximate)
Final rst-stage and second-stage manifold pressures
must be within the allowable ranges for the gas being
used. For Natural Gas: Check the furnace rate by observ-
ing gas meter, making sure all other gas appliances are
turned o. The test hand on the meter should be timed for
at least one revolution. Note the number of seconds for
one revolution.
BTU/HR = Cubic Feet Per Revolution X 3600 X Heating Value
INPUT No. Seconds Per Revolution
The heating value of your gas can be obtained from your
local utility.
For LP/Propane Gas: The only check for the output rate
is to properly adjust the manifold pressure using a ma-
nometer. Typical manifold setpoint for installations at alti-
tudes from 0 to 4500 feet above sea level is 10.0 inches
W.C.
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