Weil-McLain EG Boiler Series 3 Not Firing

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Old 11-11-20, 12:32 PM
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Weil-McLain EG Boiler Series 3 Not Firing

I have a Weil-McLain EG Boiler series 3 (model number:PEG-35-SPDN-S). It is a gas boiler with steam heat. It won't kick on after being off for the summer. I've done a bunch of troubleshooting, and even replaced the transformer. When I jump R to G on the transformer the furnace fires up with no problems. I can't for the life of me figure out what is wrong from here.

Another thing I have noticed is that the low water cutoff light does not illuminate when the water level is low. It did when I shut the boiler down last spring. I'm not sure if the tiny bulb is just out, or if this is the root of the issue. I'd greatly appreciate any help.
 
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Old 11-12-20, 05:25 AM
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Could it be that you water pressure is low.
 
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Old 11-15-20, 07:13 AM
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No. Water pressure is fine.
 
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Old 11-15-20, 08:00 AM
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Hi, jumping R G on the transformer makes no sense, what type of thermostat do you have you tried jumping RW on the stat? It’s not water pressure but water level in the boiler.
Geo 🇺🇸
 

Last edited by Geochurchi; 11-15-20 at 10:46 AM.
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Old 11-15-20, 08:34 AM
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I have 24 volts at C and R, but not at C and Y. I just bought a new Honeywell CT87K to see if my thermostat was bad, but that didn't work.
 
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Old 11-15-20, 08:47 AM
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I did try jumping R and W at thermostat. Nothing. Also not getting 24v at thermostat. I don't know what to check at the boiler to resolve the issue. Clearly, I'm not an expert at this, and I appreciate your help.
 
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Old 11-15-20, 12:12 PM
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A,
Pics would help a lot to see what you have. Your boiler as all heating units are a series circuit wiring starting at the fuse box. Check your breaker. You have a 24V system so your 120V wire from your breaker goes to your service switch on the boiler then to a 24V transformer then to your t-stat and so on. If you are not getting power to your stat then start with the breaker and check for power between there and the stat.

I would say to jump your stat wires but that would be useless if you are not getting any power there to begin with. Check for 120 in and 24 out of your transformer to the stat. It all starts with the stat so even if your LWCO is calling you would still have 24V at the stat.

Hope this helps a little.
 
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Old 11-15-20, 12:22 PM
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This boiler uses a fan center as a controller. That means it has a transformer and a relay mounted on a 4" square plate. R and G are used to activate relay thus activating the boiler.

Check for 24v power from R to C on that transformer.
 
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Old 11-15-20, 04:20 PM
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Yes, jumping R-G at the relay should turn the boiler if the relay is good. If you have replaced the T-stat you can most likely rule that out as well. If you jump your R-W wires at the stat and it doesn't turn the boiler on then it is most likely your thermostat wires. Do you have a multimeter and know how to use the continuity setting? If so, disconnect the wires from RG and jump them together, then disconnect from the stat and test continuity there.
 
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Old 11-15-20, 07:39 PM
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I appreciate everyone's help very much!

I do have a multimeter, and know how to check for continuity, but I'm not sure I understand what you're saying. This is probably a braindead question, but if I use the multimeter and connect one probe to R and the other to G at the thermostat end, should there be continuity? There is not continuity when I do that.
 
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Old 11-15-20, 07:45 PM
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I'll post some pics tomorrow afternoon. The wiring looks like a mess to me, but it's been that way for 11 years and worked just fine. I'm also not experienced with boilers, so my opinion is probably meaningless. I have two of the same boilers (it's a two family house), and both boilers are wired in the same way. I thought that having one working and one that is not would be an advantage to figure this out, but it hasn't been so far. Thanks so much for your feedback and help.
 
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Old 11-15-20, 07:52 PM
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Oh, and I meant to say that I do have 24V between R and C.
 
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Old 11-17-20, 06:40 PM
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I just want you to test the continuity of the thermostat wires, not connected to anything. Disconnect the wires from R-G at the relay, disconnect from R-W at the stat, twist the unconnected wires together at either end, go to the other end and touch one probe to each wire when the multimeter is set to continuity, if you have continuity your meter should zero out the same way it will if you touch just the probes together by themselves. If you don't zero out then you don't have continuity, a continuous circuit. It means you have a break in the wires somewhere. That is why the stat won't turn the boiler on, but connecting R to G at the relay will
 

Last edited by poorplmbr; 11-17-20 at 06:48 PM. Reason: Adding content
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Old 11-18-20, 01:34 PM
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I may be missing something here but if your relay terminals R & G supply the power to your R & W terminals on your stat what are R & C terminals connected to and why do you have 24V to them.
 
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Old 11-19-20, 03:37 AM
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Spott

Spott , Yesterday 03:34 PMI may be missing something here but if your relay terminals R & G supply the power to your R & W terminals on your stat what are R & C terminals connected to and why do you have 24V to them
. Spott, R-C are your 24v transformer terminals from the onboard transformer of the relay. G is just the contact for energizing the relay from R when the thermostat closes and brings 24volt to it.
pelling
 

Last edited by poorplmbr; 11-19-20 at 03:42 AM. Reason: S
 

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