Weil-Mclain CGa won't fire, pilot on, possible short on the Y line

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Old 04-07-11, 06:13 AM
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Weil-Mclain CGa won't fire, pilot on, possible short on the Y line

Hi, I need help locating my issue. My boiler was working fine intil i turned the thermostat down to 45 when I left for the weekend. I can back and it would not light. Pilot is on. I diagnosed that the Transformer was bad, ordered a new one with new relay. Installed and now the transformer and relay surge. If i open the circuit for the limit switches or any of them connected on the Y line, I can hear the relay activate, the damper turns, the circulator works but it won't fire up. Where is the problem? I need help. I prnted all the sheets from the Weil-Mclain site for troubleshooting. I have 24 VAC at the transfromer and gas valve.
 
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Old 04-07-11, 07:54 AM
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Should I be getting contunity betweeen the Ground (green wire) and the yellow wire?
 
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Old 04-07-11, 08:08 AM
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Follow your troubleshooting guide. The block diagrams with the series of events should tell you. Sounds like the gas valve is bad if you are getting 24v. I will try to look up your manual.

Mike NJ
 
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Old 04-07-11, 08:15 AM
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Page 51. If you follow the sequence it says change the gas valve.

http://www.weil-mclain.com/en/multim...1-009_0107.pdf

Mike NJ
 
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Old 04-07-11, 08:21 AM
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Hi Mike, What I just did was jumper the pin 2 and 5 and the relayy and transformer are no longer buzzing and chattering/shorting which leaves me to beleive that the damper harness may be bad? When I tried it however, the boiler still didn't fire.
I forced the damper open this time because it wasn't open and I think I may have broken it.
I'm going to order the gas valve. If there a way to check if the damper motor still works, it was working yesterday.
 
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Old 04-07-11, 08:33 AM
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Page 50 shows about the damper. There is a switch that lets you open and close manually. You may have broke the actuator.

If you have 24 volts at the gas valve then the damper end switch is working. If the damper does not work it will not allow the gas valve to open.

You can jump the damper out to test only. Pag 51 at bottom of page.

Remove damper harness from
damper harness plug.
TEMPORARILY install jumper
between terminal 2 and
terminal 5 on damper plug in
boiler wiring harness. Does boiler fire?

http://www.weil-mclain.com/en/multim...1-009_0107.pdf

Mike NJ
 
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Old 04-07-11, 08:38 AM
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I tried that and it didn't fire and the Short state stopped on the relay and transformer which is a good thing. I may have 2 problems. Gas valve bad and could the damper also have gone and created issues to shorting the system? I tried the manual/automatic thing, it's not reponding anymore
 
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Old 04-07-11, 08:53 AM
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What damper do you have? You can manually open it as described. Leave it open. If you get 24 volts at the gas valve then you have it open in the correct position.

Here is a example of the vent damper you may need. I dont know your actuall part #

381-800-475 - Weil Mclain 381-800-475 - 5" Vent Damper Assembly

Here is a example of the gasvalve you may need.

511-044-360 - Weil Mclain 511-044-360 - Gas Control Valve For CG, EG, CGA Boilers (Sizes 25-6)

Mike NJ
 
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