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1. With gas OFF, connect manometer to manifold pressure tap
on the outlet of gas control valve. See Fig. 51Use a
manometer with a 0 to 12 inches of water column range.
2. Turn gas ON. Operate the furnace on High Heat by using a
jumper wire on the R to W1 & W2 thermostat connections
on the furnace control board.
3. Remove manifold pressure adjustment screw cover on
furnace gas control valve. Turn adjusting screw
counterclockwise to decrease the manifold pressure and
clockwise to increase pressure. See Fig. 51
NOTE: Adjustment screw cover MUST be replaced on gas control
valve before reading manifold pressure and operating furnace.
ON
OFF
HI
LO
25--24--98a
HONEYWELL
INLET
Pressure
Tap --
1
/
8
OUTLET
Pressure
Tap --
1
/
8
Regulator
Adjustment
Under Cap
A07792
Fig. 51 -- Typical Gas Control Valve (Honeywell)
4. Set manifold pressure to value shown in Table 7,or Table 8.
5. Operate the furnace on Low Heat by using a jumper wire on
the R to W1 thermostat connections on the furnace control
board.
NOTE: The SW1 DIP switch #3 should be in the ON position to
set the Low Heat manifold pressure. (See wiring diagram.)
6. Repeat steps 3 and 4 for Low Heat operation.
7. When the manifold pressures are properly set, replace the
adjustment screw covers on the gas control valve.
8. Remove the jumper wires from the thermostat connections
on the furnace control board. Remove manometer
connection from manifold pressure tap, and replace plug in
gas valve.
9. Return SW1 DIP switch #3 to previous setting.
10. Check for leaks at plug.
Natural Gas Input Rating Check
NOTE: The gas meter can be used to measure input to furnace.
Rating is based on a natural gas BTU content of 1,000 BTU’s per
cubic foot. Check with gas supplier for actual BTU content.
1. Turn OFF gas supply to all appliances and start furnace. Use
jumper wire on R to W1 and W2 for High Heat.
2. Time how many seconds it takes the smallest dial on the gas
meter to make one complete revolution. Refer to Example.
3. Repeat steps 1 and 2 with jumper wire on R to W1 for Low
Heat.
NOTE: If meter uses a 2 cubic foot dial, divide results (seconds)
by two.
NOTE: SW1 DIP switch #3 must be in ON position. (See Furnace
Wiring Diagram). Return SW1 DIP switch #3 to previous setting
after check.
Example (BTUH)
Natural Gas
BTU Content
per cu. foot
No. of
Seconds
Per Hour
Time Per
Cubic Foot in
Seconds
BTU Per
Hour
1,000 3, 600 48 75,000
1,000 x 3,600 ÷ 48 = 75,000 BTUH
To Determine the appliance kW input rate from a .05m
3
test dial
that has been clocked at 80 seconds for one complete revolution.
Example (kW)
Number of
seconds per
hour
Number of
seconds per
complete
rotation
Size of test
dial
(.05m
3
)
kW m
3
/h
3,600 80 .05 2.25
3,600 ÷ 80x.05=7.2m
3
/h
2.25m
3
/h x 10.35 kWh/m
3
= 23.28 kW
23.28 x 3.412 = 79,431 BTU
4. Remove jumper wire from R to W1 and W2.
5. Relight all appliances and ensure all pilots are operating.
Main Burner Flame Check
Allow the furnace to run approximately 10 minutes then inspect the
main burner and pilot flames. See Fig. 52.
Check for the following (Fig. 52:
• Stable and blue flames. Dust may cause orange tips
or wisps of yellow, butflames MUST NOT havesolid,
yellow tips.
• Flames extending directly from burner into heat ex-
changer.
• Flames do NOT touch sides of heat exchanger
.
If any problems with main burner flames are noted, it may be
necessary to adjust gas pressures, or check for drafts.
Burner Face
A07734
Fig. 52 -- Main Burner
NOTE: For Igniter location see Fig. 53.
2
1/
16
(52.4)
5
/
16
(8)
1
/
4
(6.4)
A07735
Fig. 53 -- Igniter Location
Temperature Rise Check
The blower speed MUST be set to give the correct air temperature
rise through the furnace as marked on the rating plate for both High
Heat and Low Heat operation. T emperature rise is the difference
between supply and return air temperatures.
58HDV