# Vermont Castings pilot problem



## Vermont Mike (Dec 3, 2018)

Hello.

I have a 22 year old Vermont Castings Radiance Model 2600.  The pilot light extinguished some time ago. 

Button in, click on the piezo, pilot lights with strong flame through thermopile and thermocouple.
Hold for 3 minutes, pfft,  pilot flame quits.

Haven’t checked voltages yet.  From everything I’ve read on this informative forum it’s probably the thermocouple.  I’ve cleaned, vacuumed and emeried  the thermopile and surround.

If there are any suggestions I’d appreciate them.
Cheers, Mike


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## DAKSY (Dec 3, 2018)

Take reading on the thermocouple (TC).
You will probably need an extra pair of hands to do this.
Get a multimeter & set it to VDC.
Unscrew the TC from the gas valve & put one of
your probes on the EXTREME end & the other one
somewhere on the Copper sheathing. 
Light the pilot & hold the knob in.
Read the mV on the TC, which shouldn't be lower 
than 28 mV.
If the reading is lower, replace it.


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## wooduser (Dec 4, 2018)

http://www.fireplaces-rochester-ny.com/manuals/VERMONT CASTINGS/Gas Stoves/Radiance.pdf

Here is a link to the manual; for your fireplace. Page 30 has an illustration of what the pilot flame should look like.  

Both the thermocouple on the left and the pilot generator of the right should be engulfed by a lobe of the pilot flame.

You want to examine the thermocouple lobe with particular care since that's the part that helps keep the pilot lit.

The pilot flame should be a sharp blue flame,  like a small blowtorch.  If it's a lazy flame like a candle flame has yellow tips or is failing to due a good job of engulfing the thermocouple,  the pilot orifice is probably dirty and needs to be cleaned.

A dirty pilot burner is a much more common problem than a failed thermocouple,  so checking that carefully is worthwhile,  in my opinion.  

But if you have a good pilot flame that is engulfing the thermocouple,  then it's probably a bad thermocouple.


Measuring the thermocouple voltage output as suggested by Daksy is also worthwhile,  since you could have a good thermocouple putting out proper voltage but a bad gas valve that isn't using that voltage properly to keep the pilot lit.


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## Vermont Mike (Dec 4, 2018)

Thanks Daksy  and wooduser.

I do have the manual and the flame is sharp blue and enveloping the lobes well.

I’m gonna do a more thorough cleaning then check the voltages. I’m away for a little bit so I’ll be back to you in a couple of weeks.

Thanks much. Cheers, Mike


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## k0wtz (Dec 6, 2018)

Vermont Mike said:


> Thanks Daksy  and wooduser.
> 
> I do have the manual and the flame is sharp blue and enveloping the lobes well.
> 
> ...


do your self a favor run down to the hardware store and get a thermocouple 5 bux or so.  if you put it in and the thing doesn't light you will need a new gas valve.  I just redid a Vermont castings stardance stove smaller but same theory of operation!  let me know!


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## Millbilly (Dec 6, 2018)

k0wtz said:


> do your self a favor run down to the hardware store and get a thermocouple 5 bux or so.  if you put it in and the thing doesn't light you will need a new gas valve.  I just redid a Vermont castings stardance stove smaller but same theory of operation!  let me know!


Not necessarily


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## wooduser (Dec 6, 2018)

k0wtz said:


> do your self a favor run down to the hardware store and get a thermocouple 5 bux or so.  if you put it in and the thing doesn't light you will need a new gas valve.  I just redid a Vermont castings stardance stove smaller but same theory of operation!  let me know!




You wont find a thermocouple for this application in a hardware store.  If you remove it and take it to a fireplace shop they may have one they'll sell you for $25 or so.  Many shops wont sell parts to DIYers though.


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## Millbilly (Dec 6, 2018)

If this is a bvent model you need to check the flu limit or spill switch.  I would TEMPORARILY jump the flu switch.  I can't stand servicemen that do this as a permanent fix as it is an important safety mechanism.


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## wooduser (Dec 6, 2018)

This is a direct vented stove,  quite different than a stove with a draft hood using B vent. No draft hood on a direct vented stove and thus no spill switch.  So that at least is not a worry!


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## Millbilly (Dec 6, 2018)

wooduser said:


> This is a direct vented stove,  quite different than a stove with a draft hood using B vent. No draft hood on a direct vented stove and thus no spill switch.  So that at least is not a worry!


By no means a VC expert here but are you sure that manual you linked is for his 22 year old radiance 2600?  Also did the 2600 only come as a direct vent model?  I know some other brands use one name but will offer bvent or direct vent models.


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## k0wtz (Dec 7, 2018)

Some VC stoves could be ran direct vent or b-vent...  Primarely the direct vent came into play for those that wanted to vent out the wall.  Again in my readings a direct vent stove is supposed to be more efficient as it takes air from the outside for combustion I dont think it really makes much difference with stoves!

Our VC stove was made in the late 70s so B-Vent was all that was available in that time period.  The more I read on free standing gas heating stoves efficiency is not their forte in operation.  The only gas stove that might be efficient was one built by Lennox since sold to someone else a favorite ploy of manufactures to get out of their warrantees!


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## Vermont Mike (Dec 18, 2018)

Thanks all. It’s a B-Vent Radiance 2600. The manual suggested above seems to have a different thermopile/thermocouple spark set-up. Here’s a picture.

I’m gonna check voltages later.  I’m not sure what the flu limit or spill switch is.


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## Vermont Mike (Dec 18, 2018)




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## Vermont Mike (Dec 18, 2018)

I disconnected the center (TH/TP) wire, lit the pilot and measured 25mv initially climbing to 60 mv as the thermopile heated.

So, is the thermopile ok?  So the problem may be the gas valve?

Cheers, Mike


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## wooduser (Dec 18, 2018)

Vermont Mike said:


> View attachment 236093
> 
> I disconnected the center (TH/TP) wire, lit the pilot and measured 25mv initially climbing to 60 mv as the thermopile heated.
> 
> ...




Well I found the following reference to a B vented Vermont Castings Radiance 2600:

http://www.cozycabinstoveandfireplaceparts.com/cgi/display.cgi?item_num=2600-2603

Part #55 is listed as a spill switch,  presumably checking for spillage from the draft hood.  That kind of switch will typically shut off the pilot light if it opens  ---and if you have a poor electrical connection,  that's a good reason why the pilot wont stay lit,  often enough.

The picture of the gas valve reveals that you have a thermopile system that powers a magnet to hold open the pilot burner gas valve and to open the main burner gas valve.

You have three connections on the gas valve:  TH, TH/TP,  and TP.  TH/TP is the common or "ground" side of the circuit.

Voltage to the TP  connection energizes the pilot burner magnet,  to hold that open when you release the gas valve plunger,  and that's probably in series with the spill switch.

So what you want to do is to measure the millivolts between TP and TH/TP after you've lit the pilot and it's had a chance to warm up. 

My memory of what millivolts are needed to keep the pilot lit are hazy  ----perhaps someone else can contribute that voltage.


You should be able to trace two wire connections from the pilot generator  ----one to TH/TP and the other to TP.

You can see two wires forming a cable,  one to TP and the other to TH.  They should be going to a switch to turn on the main burner gas.  Power from the TP connection turns on the main burner gas connection at TH if that switch is closed.

You should find a wire going to the spill switch attached to the wire going to TP from the thermopile.  

If the spill switch opens,  it shorts out the voltage going to TP and the pilot wont stay lit.  There's a reasonable chance that a bad switch or bad wire is causing that wire to be grounded when it shouldn't be,  causing your problem.


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## Vermont Mike (Dec 19, 2018)

Ok. I found the spill switch. I shorted it at the disc and tried the pilot again. No joy.

I just ordered a Monessen 26D0566 thermopile just in case.

Still troubleshooting!

Cheers, Mike


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## Vermont Mike (Dec 19, 2018)

Oh yeah. All the wiring appears good but I’ll do some continuity checks tomorrow.

Thanks everyone for all the help especially  Wooduser and Daksy


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## Millbilly (Dec 19, 2018)

TP readings WAY too low.  You should be looking for 450mv plus with the switch off.  Send a picture of the pilot assembly with it lit.


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## Vermont Mike (Dec 19, 2018)

Millbilly said:


> TP readings WAY too low.  You should be looking for 450mv plus with the switch off.  Send a picture of the pilot assembly with it lit.


Whoops. My error, Millbilly. It was 250 mv within seconds of lit pilot, climbing to 600mv after 40 seconds.


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## wooduser (Dec 19, 2018)

Vermont Mike said:


> Ok. I found the spill switch. I shorted it at the disc and tried the pilot again. No joy.
> 
> I just ordered a Monessen 26D0566 thermopile just in case.
> 
> ...




You want to temporarily disconnect the spill switch to test the pilot burner and gas valve.  When it's shorted to ground it drains off the millivolts to ground and the pilot wont stay lit.

So try disconnecting it from the gas valve and try it again.


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## Vermont Mike (Dec 19, 2018)

to test the pilot burner and gas valve.  When it's shorted to ground it drains off the millivolts to ground and the pilot w


wooduser said:


> You want to temporarily disconnect the spill switch to test the pilot burner and gas valve.  When it's shorted to ground it drains off the millivolts to ground and the pilot wont stay lit.
> 
> So try disconnecting it from the gas valve and try it again.
> lit.
> ...


Thanks Wooduser. That makes sense. I’ll do exactly that and try it again. That’ll be tomorrow though. 

I will get back to you.  Thanks again. Hoping for flames by Christmas!


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## Vermont Mike (Dec 20, 2018)

Vermont Mike said:


> Oh yeah. All the wiring appears good but I’ll do some continuity checks tomorrow.
> 
> Thanks everyone for all the help especially  Wooduser and Daksy


Here’s the lit pilot


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## Vermont Mike (Dec 20, 2018)

Disconnected spill switch wiring. No joy. Same thing. Pilot lights ok. Strong blue flame on thermopile. Release pilot switch slowly. Flame extinguishes.


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## wooduser (Dec 20, 2018)

Vermont Mike said:


> Whoops. My error, Millbilly. It was 250 mv within seconds of lit pilot, climbing to 600mv after 40 seconds.



I saw your post that disconnecting the spill switch made no change.

The next thing to do would be to turn the main burner on switch to off,  and measure the millivolts between TH/TP and TP and let us know what they are.

When you push against the gas valve to get the pilot gas to turn on,  you are manually opening a safety valve that is usually held open by an electromagnet powered by voltage between TP and TH/TP.  If sufficient voltage is present,  the magnet should hold the gas valve open when you release it.  (If the pilot goes out,  the pilot valve snaps closed so that all the gas is off when there is no pilot light available to light the gas)


So what are the millivolts then?

If the pilot still doesn't stay lit,  turn the main burner gas switch to on and do the same test again.  

Withe the main burner gas control switched on,  you are powering both the pilot burner gas valve magnet and powering the main burner gas valve,  although the main burner gas will not turn on at that point.

What are the millivolts at that point?


Sorry if this seems drawn out.  We're getting close to deciding what the problem is.

.


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## Vermont Mike (Dec 20, 2018)

No, thanks for your time Wooduser.

Ok. I’m using the TOP and CENTER screw connection points(as shown in picture a few posts back) I get:

650 mv with pilot on and main burner switch OFF

250 mv with pilot on and main burner switch ON


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## wooduser (Dec 20, 2018)

Unfortunately,  that indicates a bad electric gas valve.

650 millivolts is actually more voltage than you ought to have.  That suggests that the pilot valve electromagnet that holds the pilot gas on when you quit holding the valve open is bad,  the circuit is open,  not using the millivolts it should to energize the electromagnet..

You can check the resistance between TP and TH/TP  ---- you'll likely find that an open circuit when the circuit needs to be complete to energize the magnet.

The millivolts drop when the switch is turned on because they are being consumed by the main burner gas valve solenoid when it is energized. 

I recommend against DIY replacement of the gas valve.  It's just more than a do it yourselfer should take on,  and the main burner gas pressure needs to be set when the new valve is installed. That's my bias,  anyway. 

You might want to make a note of the make and model of the electric gas valve when you are shopping for service.  A repairman ought to be able to bring a suitable replacement valve with him with that information.

Sorry this wasn't a simpler repair.  A bad spill switch or bad thermopile would have been good DIY repairs,  and much more common than needing to replace the electric gas valve.


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## Vermont Mike (Dec 21, 2018)

wooduser said:


> Unfortunately,  that indicates a bad electric gas valve.
> 
> 650 millivolts is actually more voltage than you ought to have.  That suggests that the pilot valve electromagnet that holds the pilot gas on when you quit holding the valve open is bad,  the circuit is open,  not using the millivolts it should to energize the electromagnet..
> 
> ...


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## Vermont Mike (Dec 21, 2018)

Double dam.

I don’t mind calling in a pro.  I’ll check the gas valve part number.  My concern is getting someone that can deal with an old piece and fix it successfully.

Wish me luck.  Thanks for all your help.  I’ll let you all know how it works out.

Thanks, Mike


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## Vermont Mike (Dec 21, 2018)

Vermont Mike said:


> No, thanks for your time Wooduser.
> 
> Ok. I’m using the TOP and CENTER screw connection points(as shown in picture a few posts back) I get:
> 
> ...



I’ll probably install the thermopile when it gets here.

Check some continuities and voltages. Keep plugging away.


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## wooduser (Dec 22, 2018)

Vermont Mike said:


> I’ll probably install the thermopile when it gets here.
> 
> Check some continuities and voltages. Keep plugging away.




What I'd do to verify my conclusion is to disconnect the black wire with the clip on the end,  which is the w wire leading to the pilot valve magnet.  Check the resistance in ohms from that wire to chassis ground.   If the magnet is good,  you ought to get a resistance of several ohms.  If the magnet wire is burned out or broken as I suspect,  it would be an open circuit.

I'd pull the wire clip off so you are measuring directly to the wire and  have noting else attached to the circuit.


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## Millbilly (Dec 22, 2018)

I just reread this thread and think you might have gotten bad information. I'm not exactly sure how this is wired without looking at it. A lot of older stoves are not necessarily wired how the manual says.  That being said I still think it could be the spill switch. Someone else instructed you to disconnect it.. no no no. You need to Jump it.  The spill switch is a bimetalic switch that is typically closed, it opens when too hot. So you need to disconnect the wires from the switch and then connect them to eachother. 
Next if the burner does not turn on you need to check the pressure on the P out port.  If you are getting pressure then you need to check for burner line/orifice obstructions.
If you are jumping the spill, the switch is dropping your mvs from 600 to 250, and you have 0 pressure out, then I'm fairly certain you have a bad valve. You can to that resistance test to confirm.


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## wooduser (Dec 22, 2018)

Millbilly said:


> That being said I still think it could be the spill switch. Someone else instructed you to disconnect it.. no no no. You need to Jump it. The spill switch is a bimetalic switch that is typically closed, it opens when too hot. So you need to disconnect the wires from the switch and then connect them to eachother.





I was presuming that the spill switch was normally open and if it closed shorted to ground.  I find that a common arrangement.  But Millbilly is quite correct,  what he describes is an equally possible way to wire the switch.  

If there is only one wire going back to the spill switch,  with the other side of the switch grounded to the fireplace sheet metal,  the testing method I suggested,  disconnecting the wire to the switch,  is good.

If you find two wires going back to the spill switch,  then Millbilly's method would be the one to use,  and connecting a jumper wire across the switch to eliminate it electrically and then checking to see if the pilot stays lit would be the way to test it.

Sorry my answer wasn't more complete.  I should have included Millbilly's test as well.


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## wooduser (Dec 22, 2018)

Millbilly said:


> Next if the burner does not turn on you need to check the pressure on the P out port. If you are getting pressure then you need to check for burner line/orifice obstructions.




I'm not clear on what you are suggesting here,  Millbilly.  As I understand it,  Vermont Mikle is getting gas to the pilot burner which lights OK but doesn't stay lit after giving the thermopile time to heat up.  If that's the condition,  I don't see a reason to test the pilot gas pressure.o main burner gas pressure.


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