Manifold Pressure Adjustment; Checking Gas Input Rate - Bard WG Series Installation Instructions Manual

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' elevations. Propane gas
conversion kit number WGCK-2 is designed
for conversions of units installed from 6,001'
– 10,000' elevations. These kits may be
purchased from your local distributor.
WARNING
When converting from propane (LP) gas to
natural gas, the gas orifice spuds and gas
valve spring must be replaced and the gas
valve regulator pressure must be adjusted
correctly. Failure to do so can result in fire,
injury or death. Refer to Table 8 for proper
orifice sizing.
Natural gas spring kit, part number 5603-007,
can be purchased through your local distributor.

19. MANIFOLD PRESSURE ADJUSTMENT

A 0 to 15" water manometer with 0.1" resolution and a
1/8" NPT manual shut off valve is needed to measure
actual manifold pressure.
WARNING
Correct manifold pressure is necessary for
proper ignition and burner operation. Failure
to accurately adjust pressure could cause heat
exchanger failure.
1. Turn off gas at equipment shut off 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 shut off valve in hole
vacated by plug. Make sure shut off valve is in off
position.
4. Attach manometer to 1/8" NPT manual shut off
valve just installed.
5. Slowly open equipment shut off valve in gas supply
line just ahead of furnace. Start furnace following
"Operating Instructions" on front door.
6. Slowly open 1/8" NPT manual shut off valve
leading to manometer.
7. Read manifold pressure on manometer.
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 as follows:
• Natural gas manifold pressure must be
between 3.2" and 3.8" W.C. Rated pressure is
3.5".
• Propane gas (LP) manifold pressure must be
between 9.7" and 10.3" W.C. Rated pressure
is 10".
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 shut
off 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.

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.
WARNING
Failure to adjust furnace to the proper firing
rate could cause heat exchanger failure.
Depending on local gas heating value and elevation,
the manifold pressure may need to be adjusted or the
orifices changed to get proper gas input rate. Check
with the local gas supplier to determine heating value
(BTU/cu. ft.) of natural gas in the area.
NOTE: If furnace is being installed at an altitude of
more than 6,000' above sea level, the furnace
must be derated. See Section 21 "Standard
Orifice Sizing and High Altitude Derate".
Manual 2100-587J
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