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CGi
GAS-FIRED WATER BOILER — SERIES 3 —
11a
Troubleshooting — procedure
Label all wires prior to dis-
connection when servicing
controls. Wiring errors can
cause improper and danger-
ous operation.
Never jumper (bypass) roll-
out thermal fuse element
or any other device except
for momentary testing as
outlined in
ing Charts
injury, death or substantial
property damage can re-
sult.
Before troubleshooting:
1. Have the following items:
a. Voltmeter that can check 120 VAC
and 24 VAC.
b. Microammeter with a minimum
scale range of 0-25.
c. Continuity checker.
d. U-tube manometer.
2. Check for 120 VAC (minimum 102 VAC
to maximum 132 VAC) to boiler.
3. Make sure thermostat is calling for heat
and contacts (including appropriate zone
controls) are closed. Check for 24 VAC be-
tween thermostat wire nuts and ground.
11b
Troubleshooting — components
Air pressure switch
Make sure boiler water temperature is 100 °F
or cooler before starting procedure to obtain
appropriate readings.
The boiler will not operate correctly unless
pressure switch hoses are correctly located.
The red hose connects from the right side
(negative) hose barb to the flue collector. The
white hose connects from the left side (posi-
tive) hose barb of the switch to the connector
box (between flue collector and inducer) as
shown in Figure 36, page 50.
Part Number 550-142-902/1016
Check the following:
1. Wire connectors to control module are securely plugged in at module and
originating control.
2. Air pressure switch hoses are properly and securely plugged in and are not
damaged.
3. Gas pressures:
a. With boiler off — 13" w.c. maximum natural or propane gas pres-
b. With boiler on:
Troubleshoot-
. Severe personal
4. Verify gas manifold pressure (downstream of gas valve):
a. Natural gas:
b. Propane gas:
c. If necessary, adjust gas pressure on the gas valve as shown below. After
Boiler Manual
sure upstream of gas valve.
•
5" w.c. minimum natural gas pressure or 11" w.c. propane gas
pressure upstream of gas valve.
•
3 ½" w.c. minimum natural gas pressure or 10" w.c. propane gas
pressure downstream of gas valve — Can be adjusted by regula-
tor on gas valve.
Manifold pressure, high fire: 3.50" w.c.
Manifold pressure, high fire: 10.0" w.c.
adjustments, refer to page 35 to check the flame.
Check pressure switch setting
1. See Figure 36, page 50, and Table 9.
2. Remove both air pressure switch hoses from air pressure
switch.
3. Install tees and tubing as shown in Figure 36, page 50, to
inclined manometer.
4. Turn off gas valve and set thermostat to call for heat. Inducer
will run but burners will not ignite.
5. Check for 24 VAC between both air pressure switch terminals.
Gas pressure adjustment
49
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