Boiler not firing, switching relay?


Old 12-15-19, 02:09 PM
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Boiler not firing, switching relay?

Hello, I will try to keep this as brief and clear as I can. I know very little about boilers...

We have a Weil McLain CG boiler that is 2 zones, one upstairs and one downstairs.

About a week ago, the heat wouldn't come on in either zone. I thought I heard buzzing from the bottom switching relay (please see pic). I did a little research and found that it might help if I cleaned these switches, so I blew compressed air and vacuumed both switching relays... lo and behold, when I turned the T stats back on everything worked again!

This morning we wake up to no heat again. The bottom RA832A, connected to the downstairs T stat, kinda buzzes until I tap it, then it goes quiet... but it still won't go on... maybe this is irrelevant...

With both T stats off, I decided to clean the contacts on the top switching relay again, this time using a piece of fine grit sandpaper. With the sandpaper between all 3 sets of contacts, I inadvertently touched the TOP contact with a piece of metal and THE BOILER FIRED UP!! It's working again! So... why would touching the top contact with a piece of metal make it work?

I should also mention, when either upstairs or downstairs T stats are turned on, the contacts on the switching relays close, but that wouldn't make the boiler kick on.

Also to mention, I have seen instructions on testing the switching relays using a multimeter, unfortunately I'm not confident that I can figure how to do it, even though I do have a multimeter...
Thanks for any advise you may have!
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Old 12-15-19, 02:46 PM
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So you have two relays...... one from each thermostat and for each pump. I can see one relay going bad but not both. Is that correct..... both are not working correctly ?
Old 12-15-19, 03:26 PM
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It's intermittent I think. Now that the upstairs zone is working, the downstairs one works as well when I turn it's T-stat up.

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