Furnace not firing

Andrww

Help!!
I have a wells McClain cgm 6. series 8. I can’t seem to find that model online but some are close and look almost identical. I came home to the house being cold and checked the boiler. The pilot was out. I got the pilot lit but it doesn’t seem to fire up past that. The pilot is staying lit but not firing anything else. I’m not sure what to check. Any help or troubleshooting pointers? 

mattmia2

Did you turn the knob back to "on" from pilot after you lit the pilot?

Andrww

I did. 

JUGHNE

Power is on?
Tstat batteries?

Andrww

Yes. 

JUGHNE

Flue damper installed on the exhaust flue pipe?
Can you post pictures of all controls....from a distance?

HomerJSmith

Is that a boiler or furnace? Is it a standing or intermittent pilot? An intermittent pilot has a spark ignition? A standing pilot has a pilot lite 24/7. Ok I looked it up.

https://www.weil-mclain.com/sites/default/files/field-file/cgm-pcg-series-6-manual_1.pdf

I know this is stupid, but today is my stupid day, do you have electricity to the boiler?

Could be anything between the transformer and the gas valve, the 24V safety circuit.

The pilot circuit is independent of the 24V circuit and would work when the power to the 24V circuit is inoperative.

bucksnort

Did you follow the ladder troubleshooting diagnostics to help? Without that, just call a pro.

Andrww

JUGHNE said:

Flue damper installed on the exhaust flue pipe? Can you post pictures of all controls....from a distance?

Andrww

JUGHNE

There are 2 black wires on the back side of the gas valve....is there a reset button there?

Is there a wiring diagram somewhere on the boiler, maybe back side of the door?

HomerJSmith

Does moving the manual-auto switch make a difference?

Ok, that square metal box under the transformer has a relay in it. That relay turns on the pump and the boiler.

If you want to, unscrew the two screws holding that box on, not the two screws holding the transformer on, and pull the relay straight off its socket. Plug in a new relay and screw the cap on over the relay. If that doesn't solve your issue, you will probably need professional help.

You have 120 Volts to the transformer, right? No, GFCI breaker or receptical that the boiler is plugged into, right.

https://www.supplyhouse.com/Packard-PR341-DPDT-Switching-Fan-Relay-110-120-Coil-Voltage

mattmia2

The thermopile might me bad, it might produce enough current to hold the safety valve open but not enough to pull the main valve open.

Andrww

I’ll have to check when I get home. Working now. I’m hoping the temps don’t get too low and it’ll be ok while I figure it out. I got quoted $$$ emergency service call to come diagnose and quote the repair. 

HomerJSmith

mattmia2, I thought that the pilot thermocouple only holds the secondary valve (pilot controlled valve) open. The 24 V opens up the main valve to the burners. Maybe I have this wrong.

Andrww, what you might do is turn up the thermostat for a call for heat and then take a hammer and tap the sq metal box under the transformer and see what transpires.

mattmia2

I think that is a millivolt main valve, the armored lead from the pilot looks like a thermopile and it looks like there is a jumper from the main valve terminals to where the thermocouple would normally connect.

HomerJSmith

Ya, mattmia2, you could be right.

JUGHNE

Pretty different looking valve IMO.
I am sure Tim has seen it before.

HomerJSmith

I have seen some really old thermocouples with metal wound cables, tho. But, mattmia2, you're right, it is a Thermopile. see:

https://www.amazon.com/Honeywell-VS820A1088-Power-Millivolt-Combo/dp/B003CVX94I/ref=pd_sbs_1?pd_rd_w=AISak&pf_rd_p=3ec6a47e-bf65-49f8-80f7-0d7c7c7ce2ca&pf_rd_r=6VYA69CXXTCD8D5K3EVS&pd_rd_r=e287e298-b765-4c30-9f72-d3776c222e85&pd_rd_wg=5TsWl&pd_rd_i=B003CVX94I&psc=1

https://honeyvell.energy/wa-data/public/site/gazovye-klapany-Honeywell/VS820A/Honeywell VS820A (en).pdf

So maybe the thermopile need replacing as the voltage may be too low to hold the main valve open. mattmia2, your insightful idea is spot on and replacing the thermopile would be my first chore. kudos

mattmia2

What does the label on the side of the valve say? That should clear this up.

Andrww

EBEBRATT-Ed

@Andrww

Your last picture with the relay see if the relay is pulled in. You can push (carefully) on the top front of the relay. You can put a jumper on terminals T & T (thermostat) connections. Shut the switch off while you do this. It will bypass the thermostat.

If neither of those things work you may have a bad thermopile. Do you have a test meter? Is the circulator running? Hard to tell from the picture I don't think that relay is pulled in

Andrww

I tried tapping the box under the transformer but nothing happened. Does any of the pictures show the thermal pile? Looking online I see in troubleshooting a pilot flame sensor. Is that it? 

Andrww

I have two zones. One is for the basement and one for the rest of the house. That last picture is what’s in the box that the thermostat for the basement zone goes into. I have that circulator off because I don’t heat the basement. 

HVACNUT

You can replace the pilot generator and cross your fingers, or get an electrical meter and track it down. 

mattmia2

The thermopile is that cylinder in the pilot flame that it looks like connects to those screw terminals on the gas valve(I can't quite tell because it looks like there is a second safety switch or connection inserted in with it and they both use the same type of cable). It is something like this:

https://www.supplyhouse.com/Resideo-Q313A1188-35-Thermopile-Generator-w-Push-in-Clip-1-2-Thermopile-Attaching-Nut-750-mV

Reading the voltage across it with the valve on or trying to come on will tell you if it is generating enough current.

HomerJSmith

The thermopile is rated at 750 millivolt, But measuring the voltage while connected to the gas valve yields a much lower voltage as low as 300 mv per my experience.

If it has never been replaced, it most certainly could be your problem. If you replace the themopile, take a wire brush or stainless steel scouring pad and clean the burner tubes.

The thermopile in your pic is sticking up at the pilot bracket about the dia of a pencil with the metal wrapped wires coming from the pilot assembly.

Tim McElwain

That is a 750 millivolt powerpile gas valve probably a VS820. Do you know how to troubleshoot Powerpile Systems? If not contact me at timmcelwain@gastcri.com and I will send you the procedure.

Andrww

It was the thermal pile. Cost me $ to have someone figure it out and fix it. Thanks everyone for the advice! 

EBEBRATT-Ed

@Andrww

That's not to bad but we can't post or talk prices here. Glad you have it fixed