Weil-McLain CGi 4 Series Manual page 49

CGi
SERIES 4 — GAS-FIRED WATER BOILER —
11a
Troubleshooting — procedure
Label all wires prior to dis-
connection when servicing
controls. Wiring errors can
cause improper and dangerous
operation.
Never jumper (bypass) rollout
thermal fuse element or any
other device except for mo-
mentary testing as outlined
in
Troubleshooting Charts
Severe personal injury, death
or substantial property dam-
age can result.
Before troubleshooting:
1. Have the following items:
a. Voltmeter that can check 120VAC and
24VAC.
b. Microammeter with a minimum scale
range of 0-25.
c. Continuity checker.
d. U-tube manometer.
2. Check for 120VAC (minimum 102VAC to
maximum 132VAC) to boiler.
3. Make sure thermostat is calling for heat and
contacts (including appropriate zone con-
trols) are closed. Check for 24VAC between
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 fl ue collector. The
white hose connects from the left side (posi-
tive) hose barb of the switch to the connector
box (between fl ue collector and inducer) as
shown in Figure 36, page 50 .
Part Number 550-142-302/0520
Boiler Manual
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
pressure upstream of gas valve.
b. With boiler on:
• 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
regulator on gas valve.
4. Verify gas manifold pressure (downstream of gas valve):
a. Natural gas:
Manifold pressure, high fi re: 3.50" w.c.
b. Propane gas:
Manifold pressure, high fi re: 10.0" w.c.
c. If necessary, adjust gas pressure on the gas valve as shown below. After
adjustments, refer to page 35 to check the fl ame.
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