Manual 2100-365
Page 22
19. MANIFOLD PRESSURE
ADJUSTMENT
You will need a 0 to 15 inch water manometer with 0.1
inch resolution and a 1/8" NPT manual shutoff valve to
measure actual manifold pressure.
Depending on your local gas heating value and
elevation, you may need to adjust manifold pressure or
change orifices to get proper gas input rate. Check
with your local gas supplier to determine heating value
(BTU/cu. ft.) of natural gas in your area.
NOTE: If furnace is being installed at an altitude of
more than 6,000 feet above sea level, you
must derate the furnace. See Section 21
"Standard Orifice Sizing and High Altitude
Derate".
20. CHECKING GAS INPUT RATE
It is the installer's responsibility to see that the BTU
input rate of the furnace is properly adjusted. Under-
firing could cause inadequate heat, excessive
condensation or ignition problems. Overfiring could
cause sooting, flame impingement or overheating of
heat exchanger.
8. Adjust manifold pressure by turning gas control
regulator adjusting screw clockwise to increase
pressure or turning counterclockwise to decrease
pressure. Manifold pressure must be within
allowable range below:
• Natural gas manifold pressure must be between
3.2 and 3.8 inches W.C. Rated pressure is 3.5
inches.
• Propane gas (LP) manifold pressure must be
between 9.7 and 10.3 inches W.C. Rated
pressure is 10 inches.
NOTE: For natural gas, if gas flow rate can't be
properly set within these pressure ranges
then you must change main burner orifices to
obtain proper gas flow rate.
9. Shut off furnace. Turn off gas at equipment shutoff
valve in gas supply line just ahead of furnace.
Install outlet pressure tap plug in gas control. Turn
on gas.
10. Check regulator adjustment cover screw and gas
control plug for gas leaks. Use a commercial soap
solution made for leak detection.
1. Turn off gas at equipment shutoff valve in gas
supply line just ahead of furnace.
2. Remove plug from outlet pressure tap in gas control
or gas manifold.
3. Install 1/8" NPT manual shutoff valve in hole
vacated by plug. Make sure shutoff valve is in off
position.
4. Attach manometer to 1/8" NPT manual shutoff
valve just installed.
5. Slowly open equipment shutoff valve in gas supply
line just ahead of furnace. Start furnace following
"Operating Instructions" on front door.
6. Slowly open 1/8" NPT manual shutoff valve leading
to manometer.
7. Read manifold pressure on manometer.
PROPANE (LP) GAS CONVERSION
This unit may be converted in the field for
use with Propane (LP) gas. Propane gas
conversion kit number WGCK-1 is designed
for conversions of units installed from
0 – 6,000 feet elevations. Propane gas
conversion kit number WGCK-2 is designed
for conversions of units installed from 6,001
– 10,000 feet elevations. These kits may be
purchased from your local dealer.
WARNING
Correct manifold pressure is necessary for
proper ignition and burner operation. Failure
to accurately adjust pressure could cause
heat exchanger failure.
WARNING
Failure to adjust furnace to the proper firing
rate could cause heat exchanger failure.
To Next Page
