Boiler - burner not firing

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Old 09-13-14, 08:28 AM
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Boiler - burner not firing

Hi I'm having some trouble with my system. I have hydronic heating system with a gas boiler. When the thermostat calls for heat the pumps will come on but the boiler does not kick on. Thus no hot water thru pipes. It was working just fine but this started with a new cycle of calling for heat. Thanks Jim
 
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Old 09-13-14, 08:30 AM
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Jim, you've got to at least tell us some details about the boiler...

make and model... etc

gas or oil ?
 
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Old 09-13-14, 08:39 AM
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Boiler

Gas. Utica boiler. Model#MGB150HD. Input 150000btu d.o.e. Heat capacity 124000btu. Anything else
 
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Old 09-13-14, 09:01 AM
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Is this just one 'zone' heat? Only one thermostat in the home?

the pumps will come on
You said pumpS, plural. Is there more than one pump?
 
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Old 09-13-14, 09:03 AM
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There are four zones and four pumps. All zones have the same issue
 
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Old 09-13-14, 09:22 AM
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OK, so there has to be some 'relay controls' for each pump then...

What controls the pumps? Do you have a single control panel for all the pumps, such as a Taco SR series control? or are there individual control relays for each pump?
 
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Old 09-13-14, 09:29 AM
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I believe your boiler has a motorized vent damper? Is it opening?

There are many revisions of the MGB, do you have an idea of how old it is?

Is there any other model information, such as 'revision' or 'series' on the data plate?

Is it a 'standing pilot', and if so, is the pilot lit? or is it 'spark ignition', and if so can you hear the spark try to light the pilot when there is a call for heat?
 
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Old 09-13-14, 09:43 AM
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Individual control for each pump. Rev 1 on boiler does have motorized vent has a intermitten ignition pilot. Damper is opening don't hear pilot igniting
 
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Old 09-13-14, 09:53 AM
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You're sure that you have the 'intermittent ignition' ? They were available with both intermittent and standing pilot.

What controls are on the boiler? Honeywell 8148E aquastat? and S8600 ignition module?

Perhaps you could take some pics so I don't have to ask as many questions... need to know exactly what you've got there in order to suggest course of troubleshooting.
 
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Old 09-13-14, 09:55 AM
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I'm sure about the intermitten pilot Honeywell 8148
 
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Old 09-13-14, 10:00 AM
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I should also ask if your system has a "Low Water Cut Off" installed.

Also tell us the pressure you read on the boiler gauge.
 
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Old 09-13-14, 10:00 AM
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Here's some picsName:  image.jpg
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Old 09-13-14, 10:01 AM
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I'm sure about the intermitten pilot Honeywell 8148
And the S8600M ignition module then?
 
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Old 09-13-14, 10:04 AM
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Not sure about low water cut off pressure 12lbs ignition honeywellvr8200A
 
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Old 09-13-14, 10:07 AM
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Pics are upside down sorry
 
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Old 09-13-14, 10:37 AM
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I don't see LWCO in the pics, probably don't have one...

Gas valve is VR8200... not the ignition module.

If you have spark ignition, there has to be another component such as an 8600M module, probably tucked inside the boiler near the burners...

The VR8200A gas valve is for a STANDING PILOT system, so I don't believe you will find the 8600 module and you do NOT have spark ignition.

So get on yer knees and look inside by the burners and see if the pilot is lit or not.
 
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Old 09-13-14, 10:38 AM
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Pics are upside down sorry
I'll just stand on my head, no problem!
 
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Old 09-13-14, 10:58 AM
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The pilot light is on. Sorry for your sore head
 
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Old 09-13-14, 11:40 AM
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OK then...

What you may have is a bad 'thermocouple' device. That's the thin copper tube that runs inside the burner alongside the pilot tubing. On the end of that is a 'bulb' that is heated by the pilot flame. The function is to prove that the pilot is lit before allowing the main gas valve to open. If the pilot is lit, and the valve isn't opening, it's a pretty good bet that's the culprit.

BUT, do you have a multimeter? know how to use it? You can do a simple check first... before replacing the thermocouple.
 
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Old 09-13-14, 11:41 AM
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By the way, my head is senseless... wifey been upside it so many times with the bald headed end of a broom I can't feel anything anymore!
 
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Old 09-13-14, 11:45 AM
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I have a multimeter and know how to use it. Even more sorry about that head.
 
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Old 09-13-14, 12:32 PM
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OK, set the meter up to read AC volts.

connect it to the two terminals on the gas valve (labeled TH and TR I think?) ... in any case, it will be the only two wires (except perhaps for a ground wire).

When the thermostats are calling for heat, and the boiler is not yet up to temperature, you should read a 'nominal' 24 VAC on the gas valve terminals.

If you DO read 24 VAC there when it should be firing, then it's a very good chance that the thermocouple is bad because it means that the controls are telling it to fire but it's saying :NO NO NO:

If you do NOT have 24 VAC on those two terminals, it means there's something else wrong... and there is another test we can do to determine that afterward.

Let me know.
 
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Old 09-13-14, 12:34 PM
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OH, one more thing...

Just to eliminate the 'Duuuuhhhh factor'... make sure that the knob on the gas valve is pointing to " ON " and not to " PILOT "
 
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Old 09-13-14, 12:41 PM
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Thank you NJ Trooper I'll try let you know
 
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