Checks And Adjustments - International comfort products C9MVX Installation Instructions Manual

Checks and Adjustments

Verify the input rate of the furnace.
NOTE:
WARNING
!
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in
personal injury, death and/or property damage.
Turn OFF gas at shut off before connecting
manometer.
Startup
NOTE: Refer to the start−up procedures in the "User's Information
Manual" or to the "Operating Instructions Label" on the furnace.
WARNING
!
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in
personal injury, death, and/or property damage.
If any sparks, odors or unusual noises occur,
immediately shut OFF power to furnace. Check for
wiring errors or obstruction to blower.
Gas Supply Pressure
Gas supply pressure should be within minimum and maximum
values listed on rating plate. Pressures are usually set by gas
suppliers.
Manifold Gas Pressure Adjustments
(High and Low Heat)
NOTE: Make adjustment to manifold pressure with burners
operating.
WARNING
!
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in
personal injury, death and/or property damage.
Turn OFF gas at shut off before connecting
manometer.
1. With gas OFF, connect manometer to manifold pressure tap
on the outlet of gas control valve. See Figure 45. Use 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 cap on
furnace gas control valve. Turn adjusting screw using 3/32
hex wrench, counterclockwise to decrease the manifold
pressure and clockwise to increase pressure.
Figure 45.
NOTE: Adjustment screw cover MUST be replaced on gas control
valve before reading manifold pressure and operating furnace.
440 01 2024 04
Figure 45
Regulator
Adjustment
Under Cap
INLET
Pressure
Tap −
25-24-98a
4. Set manifold pressure to value shown in Table 7, Table 8,
Table 9 or Table 10.
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.
Natural Gas
BTU Content
per cu. foot
1,000
See
To Determine the appliance kW input rate from a .05m
has been clocked at 80 seconds for one complete revolution.
Specifications are subject to change without notice.
Typical Gas Control Valve Honeywell
HONEYWELL
HI
LO
OFF
1
/
8
Example (BTUH)
No. of
Seconds Cubic Foot in
Per Hour
3,600
1,000 x 3,600 ÷ 48 = 75,000 BTUH
ON
OUTLET
Pressure
1
Tap − /
8
Time Per
BTU Per
Hour
Seconds
48 75,000
3
test dial that
43