Weil Mclain CG4 gas boiler - no fire


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Old 12-31-08, 03:23 PM
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Weil Mclain CG4 gas boiler - no fire

Furnance:
Weil Mclain CG-4-SPDN
Natural gas
Forced hot water

Here's the current situation:
- Pilot light is lit
- damper motor turns
- honeywell digital thermostat
- turned the power on and off and the relay clicks but no fire
- i assume the transformer is working due to the damper motor moving?

any help or suggestions?
what triggers the boiler to fire? what needs to happen for the boiler to turn on.

i read elsewhere that the combustion motor must run for the boiler to fire but i don't think there's a motor on this furnance.
thanks!

here's a pic of the "mess"
 
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Old 12-31-08, 05:24 PM
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The gas valve is in the "on" position?

Circulator is running?

24v to gas valve?

Try switching from automatic to manual on the vent damper.

Jumper the roll out switch. White ceramic on the left side above the burners.

Honeywell damper motor?
If so remove the cover and press on the lower right side of the circut board. It may be a loose solder connection. Pressing on it usually makes it turn on.

Effical damper? Recall Program
 
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Old 12-31-08, 06:17 PM
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Originally Posted by Ed-54
Jumper the roll out switch.
Temporarily of course... remove jumper as soon as done troubleshooting...
 
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Old 01-01-09, 06:11 PM
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Originally Posted by Ed-54
The gas valve is in the "on" position?

Circulator is running?

24v to gas valve?

Try switching from automatic to manual on the vent damper.

Jumper the roll out switch. White ceramic on the left side above the burners.

Honeywell damper motor?
If so remove the cover and press on the lower right side of the circut board. It may be a loose solder connection. Pressing on it usually makes it turn on.

Effical damper? Recall Program
the gas valve is on the "on" position...check.

circulator wasn't running at the moment.

24v to gas valve..check.

vent damper...PROBLEM...
switched it to manual hold and nothing happens. it's funny..like sometimes it turns and sometimes it doesn't. when it turns it'll go to open and then close...it doesn't stop in the middle. so i filpped on the power again (gotta do it a few times) and flip the switch to manual hold when it's open and bam the boiler fires.

so it's safe to assume the motor is the problem here? here's the part.


cover off...


any idea how much is this part?

thanks for your help...greatly appreciate it.
 
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Old 01-03-09, 09:54 AM
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changed the damper motor and it's moving but now it doesn't stop at the open position and it goes from close -> open -> close in one single turn. now it won't even open anymore.

pilot is on
the gas valve is turned to on
i think i hear the click of the relay
i tried to bypass the roll out switch nothing
 
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Old 10-01-09, 09:25 AM
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I have the exact same problem, looks like exactly the same damper vent make/model, same CG-4 boiler. Did you ever get a conclusion on the problem? I've gone over the manual and the parts list and there's no fuse I can see.. I can dig more but it's getting cold and the local propane shop doesn't service this boiler.

Basically one day it just gave up the ghost and without the damper open the boiler won't fire (of course) .. but so far no luck with repairs.

Any thoughts / strategies would be welcome!

-CB
 
 

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