Weil-McLain CGS-4E manual 11d Troubleshooting - control module lights

GOLD CGs-4E Gas-Fired Water Boiler — Boiler Manual

11d Troubleshooting — control module lights

CHART 2 — TSTAT CIRC & POWER lights flashing

— Usually indicates 48 VAC on thermostat circuit (stray voltage) —

Electrical shock hazard — Wherever you see TURN OFF POWER, follow the instructions. Failure to follow instructions could result in severe personal injury, death or substantial property damage.

• Disconnect the two external wires connected to the boiler	• If a voltage does occur under any condition, check and
thermostat leads (two black low voltage leads in J-box).		correct the external wiring. (This is a common problem
• Connect a voltmeter across these two incoming wires.		when using 3-wire zone valves.)
Close each thermostat, zone valve and relay in the external	• Once the external thermostat circuit wiring is checked and
circuit one at a time and check the voltmeter reading		corrected if necessary, reconnect the external thermostat
across the wires.		circuit wires to the boiler thermostat wires and allow the
• There should NEVER be a voltage reading.		boiler to cycle.
Did you find a voltage across the two external thermostat circuit wires?
Yes		No

•Leave external boiler thermostat connection wires disconnected from boiler.

•Troubleshoot the external thermostat circuit until you find the source of the stray voltage. (Pay close attention to the wiring connections to 3-wire zone valves.)

•Correct the problem and repeat the voltmeter test above, verifying there is no longer a voltage reading under any condition in the external thermostat circuit.

•An isolating relay may be required.

•If no voltage is found under any condition of the external thermostat circuit, connect the two boiler thermostat connection leads together (or jumper the boiler aquastat T-T terminals).

• Turn off power to the boiler for 1 minute.

• Turn on power and allow boiler to cycle.

Do the TSTAT and POWER lights still flash?

No Yes

•Boiler should now operate per the normal sequence of operation shown in Figure 18, page 33.

•Replace control module.

•Retest.

48

Part number 550-110-282/1108