Water circulating but no burner

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Old 10-28-11, 02:13 PM
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Water circulating but no burner

Hello everyone.

I went to turn on the heat for the first time this season and of course it doesn't work.

It's a natural gas boiler with a L8048B aquastat. Yeah, it's an oldie, it looked 40 years old when we moved in 10 years ago.

Anyway, when the t-stat calls for heat the circulator starts but the burner doesn't fire. There was a broken wire coming off of the relay switch in the aquastst that I fixed last year and it seems fine as I'm getting continuity through the wire and the switch.

I have a multimeter and I know how to use it, I just don't know what values I should be getting.

I'm getting about 1 volt at the t-state terminals and the wires that lead down to the powerpyle I'm getting almost no voltage at all.

Any help would be so greatly appreciated. Thanks!
 
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Old 10-28-11, 02:30 PM
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Hi,

What is the make and model boiler?

For the heck of it whats the pressure and temp read?

Next test the two leads comming from the powerpyle. You should have around 750mV I believe. If its significantly less it may not be enough juice to open the gas valve.

This is what comes up as the aquastat. Its probably the rplacement and is identical to what you have?

Check the drawing.

http://customer.honeywell.com/techli...it/95-6940.pdf

Let us know.

Mike NJ
 

Last edited by lawrosa; 10-28-11 at 02:52 PM.
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Old 10-28-11, 02:57 PM
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Hey Mike, thanks for replying!

The boiler is a Sears Homart 600.

The temp is zero and the pressure is at 22.

I'm not getting close to 750mv and the number keeps changing a little. It seems that the reading I'm getting from the wires that lead from the powerpyle to the aquastat is the same as the number I'm getting on the wires that lead from the powerpyle to the thermocouple (I think that's what it's called, the wires that go to the pilot)

Thanks again for responding, I'm in Jersey too and it got chilly here.
 
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Old 10-28-11, 03:21 PM
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OK. If a thermocouple its just a copper solid wire comming from the pilot area.

If its a powerpyle there should be a wire with two leads connected to the gas valve.

Does the gas valve sat 24v anywhere on it?

Pressure is high for the boiler not running. Drain some water off from the boiler drain to about 10 psi. Then wait a few minutes. Record the pressure and post back.

Let us know the above.
 
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Old 10-28-11, 03:46 PM
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Ok, I drained it so it said 12 lbs and its been there for about 10 minutes now.

it is a powerpyle system. There are two wires that come from the pilot and connect to the powerpyle and two that come from the aquastat and connect to the powerpyle. I'm getting the same reading on my multimeter when I check either set of terminals on the powerpyle.

I don't see 24v anywhere on the powerpyle or on anything near it.

I cannot thank you enough for your help.
 
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Old 10-28-11, 06:39 PM
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So If your not getting 750mV from the leads of the powerpile I would go ahead and replace it. I believe they are not cheap $30 bucks.

Normal Range: 600 to 750 mV.
Lowest Acceptable: 540 mV.

Patriot Supply - Q313A1022

Also the pilot is lit correct? The flame around the powerpile generates the 750 mV. How does the flame look?

Not sure but I dont think these turn off the pilot when they are bad. So measuring is the only way to tell I think.

Mike NJ
 

Last edited by NJT; 11-18-11 at 05:39 PM.
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Old 10-28-11, 06:55 PM
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Yes, the pilot is lit and it's a nice totally blue flame. Now that I think about it it did seem like I had to keep the knob pushed in an awfully long time before the pilot would stay lit.

We had the gas shut off to the boiler since the hurricane. Our power went out and we got some water in the basement and the fire department came around and shut everyone's gas off. So I just re-lit the pilot yesterday and it seemed like I had to keep the knob pushed in forever.

I'll go ahead and replace it and hopefully that solves the problem.

Once again, I just want to say thanks so much for your help.
 
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Old 10-30-11, 11:19 AM
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I installed the new thermopile generator and it was only putting out 250mv so I guessed that the pilot was not as strong as it should be. I heated the thermopile with a propane torch until it was putting out about 500mv then I turned the boiler to on and it fired up. I think I had a combination of a weak thermopile generator and a weak pilot flame. I cleaned the pilot tip a little better and its working good now. Thanks again!
 
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