Weil McLain EG50 no power after a pop

Peter1369

I heard a pop when turning my boiler on and ever since then it had no power. The 2 safety switches are on and there is power to the switches. Does the S84A-85 make a pop sound when it fails?

Jamie Hall

Lots of electrical things make a pop sound when they fail. Circuit breakers and fuses most notably. Start back at your power panel and go on from there, making sure that all circuit breakers are closed and fuses are intact. There may be fuses in the EG50's control boards as well.

If you find something open or a blown fuse — find out why before you try to reclose it or replace it…

EdTheHeaterMan

There are too many EG50 boilers to know which one you have. This control supplement has many for the different EG 50 wiring / control designs. Can you provide the CP number or select which control system you have from this manual?

https://www.weil-mclain.com/sites/default/files/field-file/eg-peg-egh-control-supplement-manual_1.pdf

Peter1369

The breakers are ok.

The model is EG50SPDN series 4.

Peter1369

Where would I find the CP#.

Peter1369

EBEBRATT-Ed

Looks like a fuse on the damper connector. You really need a test meter and know how to use it to find the problem. Or call in a technician who has one.

Peter1369

There is no fuse the wire goes from the rollout TPE to the transformer. There is a spill switch that goes to the draft hood.

I don't think I'm getting any power from the transformer. I tested it with a voltmeter. I have to figure out what caused it to fail.

HomerJSmith

@Peter1369

I don't know what "pop", "no power", "2 safety switches are on" mean. More descriptive information would be helpful as to what you tested, etc.

Is the vent damper fully open?

EdTheHeaterMan

According to the wiring diagram, you have a standing pilot gas valve on a steam boiler. The only "POP" that I can think of that would cause the boiler to not power up is the transformer. The part you called S84A-85 is actually Weil McLain Part number 510-312-166 (that is the current replacement part number) but, you don't need to pay the Weil McLain markup for that part.

https://www.supplyhouse.com/Weil-Mclain-510-312-166-Transformer-120-24V

You can find that same part here for much less

https://www.supplyhouse.com/Resideo-AT72D1006-Plate-Mounted-120-Vac-Transformer-with-9-in-Lead-Wires

You will want to add a 3 amp circuit breaker to the R terminal on the new transformer (whether you purchase the WM of the Honeywell) so you can save the transformer from failure while you find the short circuit.

https://www.supplyhouse.com/ESP-POP3-Lil-Popper-3-Amp-Control-Circuit-Tester-120-250v

This would be your updated wiring diagram if you use the lower cost transformer and the circuit breaker to protect the new transformer from suffering the same fate as the original.

And this is the important part zoomed in.

Since the new part does not have the G and the Y screw terminals included you will replace than with a wire nut connector. The Y and the G on the old part do not have any connetion the the internal wiring of the transformer. They just have some convenient screw terminals ,so the factory does not need to spend extra $$$ on wire nuts.

HomerJSmith

Usually a relay plugs in at the red arrow.

EdTheHeaterMan

I have a question about the thermostat you are using.

Did you happen to try to connect a Smart Thermostat that requires a C terminal along with the R and the W terminal on the thermostat? That may be the reason for your POP

Peter1369

Thank you Edward.

I have a 11 year old Ritetemp thermostat.

HVACNUT

Get a whole new fan center control. The pop you heard was likely the transformer. And the base of the terminal board is lifted off on the right side. Shut the power off, stick your head in there and give it a sniff. Probably pretty rank. Add an in-line fuse like Ed said, because it could be it was the transformers time to pass, or there could be a short somewhere.

Peter1369

I don't see a fan control on the diagram.

The parts came in today but the board is cracked. I don't think it will matter.

Peter1369

I'll update tomorrow

Peter1369

It works now.

I replaced the transformer and added a lil popper(genius idea).

Thank you for your help.

JakeCK

Since it is now up and running, we can let you in on the secret...

The pop you heard was really the magic smoke escaping. ;)

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1822081#Comment_1822081

That relay is for operating a fan when used on a old gas furnace that has been upgraded with a central AC or with a boiler that uses a circulator to move water around the system. Since this is a steam boiler, you do not need the relay since there is no Fan or Circulator. That is why Weil McLain sells that without the relay for steam boilers 510-312-166 and with the relay for water boilers 510-312-167. I used to be the Weil McLain part guy at the supply house I worked for. So any WM part for boilers from 1996 and before are memorized. The Honeywell R8285A1048 would be a lower price replacement for that part with the relay included. and the AT72D1006 is even cheaper but does not have the G, Y, and W wire connectors on it. You need to use wire nuts in lieu of screw connectors.