A strange problem with Majestic / Vermont Castings DV580 - I need help!

[d-hosh]

I have a Majestic / Vermont Castings DV580 rear vented - with a strange problem. When the fireplace is off the pilot light seems to run fine. I have no problem starting the fireplace, but it will run for a variable amount of time (usually 15-20 mins or so) and then suddenly shut off - the main burner and pilot light extinguish and a few seconds later I can hear the gas valve close with a "click". It then seems like I have to wait about 15 minutes until I can restart the pilot light - if I try sooner the igniter just sparks but the pilot won't light. Can thermopiles get too hot and not produce voltage?

I find I can run the fireplace 10 minutes with no problems, but if I push 20 minutes it will almost always shut down.

I have had many "technicians" come out and they are stumped. They have replaced the thermopiles (twice), removed the shield around the pilot (and replaced it), replaced the gas valve, put fibreglass insulation around the gas valve, cleaned the burner, repositioned the logs many times.....

Of course the dealer claims no responsibility because the contractor who built my house installed the fireplace.

I am at wits end! Our winters are cold! Any help would be much appreciated!!

 

[jtp10181]

If the pilot goes out its not the thermopile, its the thermocouple. But if you hear the valve click AFTER the pilot goes I am guessing there is still gas flowing to the pilot but not the right fuel / air mixture for it to burn. The click you hear is when the millivolts coming off the thermocouple gets too low and the valve shuts off all gas flow as a safety method.

This is a free standing stove right?

Does it vent straight out the rear and out the house? How long is the vent? Has anyone verified it is installed per mfg specs? Does it have the proper mfg specced termination cap and venting system?

Yes thermopiles and thermocouples can overheat and loose voltage, but its rare, usually only seen on gas logs.

Sounds like the dealer does not really understand whats going and is just throwing parts at it (unfortunately this seems to be how must gas fireplace techs fix problems). Has a tech actually stayed with the unit on with meters hooked up to determine the exact reason why the pilot is going out?

 

[DAKSY]

I have a Majestic / Vermont Castings DV580 rear vented - with a strange problem. When the fireplace is off the pilot light seems to run fine. I have no problem starting the fireplace, but it will run for a variable amount of time (usually 15-20 mins or so) and then suddenly shut off - the main burner and pilot light extinguish and a few seconds later I can hear the gas valve close with a "click". It then seems like I have to wait about 15 minutes until I can restart the pilot light - if I try sooner the igniter just sparks but the pilot won't light. Can thermopiles get too hot and not produce voltage?

I find I can run the fireplace 10 minutes with no problems, but if I push 20 minutes it will almost always shut down.

I have had many "technicians" come out and they are stumped. They have replaced the thermopiles (twice), removed the shield around the pilot (and replaced it), replaced the gas valve, put fibreglass insulation around the gas valve, cleaned the burner, repositioned the logs many times.....

Of course the dealer claims no responsibility because the contractor who built my house installed the fireplace.

I am at wits end! Our winters are cold! Any help would be much appreciated!!

Check the manual to see if there's a wiring schematic. See if there's a spill switch located near the top of unit & if there is, test it.
You can pull it out of the loop by making a small jumper wire & if your stove runs with the jumper in there & DOESN'T shut down,
That's probably the culprit.
Probably a $20 - $25 part...
HTH

 

[d-hosh]

Thanks to all that have replied!

I followed Czarcar's advice and propped the front glass open about 3 inches and lo and behold! I ran it for 2 continuous hours with no problems!

To answer some of jtp10181's questions. This is a rear vent fireplace that vents directly out an exterior wall, so the vent is not long at all - not even a foot long. (could post pics if helpful to you). I have never had anyone verify that it was installed or vented correctly - but it is such a simple installation - and the vent cap is manufactured by Majestic - still, improper installation of the venting could be the problem. A few techs that have tried to solve the problem looked at the the way it was vented, but seemed to dismiss this as the source of the problem very quickly.

DAKSY - I looked at the installation manual, but I don't see any mention of a spill switch. I don't know what a spill switch does - but I don't think I have one.

It seems to me, because of Czarcar's suggestion and result that this is either an overheating problem or an air intake / venting problem. I don't see that there is any temperature sensor in this fireplace so I think the latter is more likely. Am I wrong? If anyone has any suggestions or next steps for an ordinary guy to take I'd appreciate it. Otherwise I think you all are going to suggest I have an installer come and make sure the intake / venting is proper.

 

[jtp10181]

That manual was hard to track down

http://www.cfmcustomercare.com/elements/uploads/files/Manual_DV360_EN.pdf

Check page 36 for the most complicated parts blowup I have ever seen in my life! Only snap switch is the fan temp sensor. I doubt a hi limit / spill switch would be going off after only 10 minutes anyway unless it was a B-Vent (and its not).

Ok, here is what we know now. Its an air flow problem, for sure. No part inside will fix it. The fire is running out of O2 so it goes out. The valve then shuts off gas supply a few seconds later as a safety feature. Exhaust or intake could be blocked, or the pipe might not be fully connected at some place causing exhaust to get sucked back into the intake which would starve out the unit. On some units the outer collar on the unit has insulation packed in it, if that's not removed before connecting the vent no air can get into the unit.

I don't know enough about this brand to give any other hints, and I don't have time to read the entire manual.

This is why you should have gas fireplaces installed by pros who know what they are doing.

If your dealers techs knew what they were doing they would have tried the glass trick on the first trip. Its easy to see a flame thats loosing O2 and you crack the glass and see if it helps. At that point they should not have replaced any parts and started looking for the air flow problem. I would have inspected the units for leaks and if none found I would contact the person who installed and ask if they want to fix the venting problem, or pay us to do it.

 

[DAKSY]

You didn't mention if you watched the flames while it
was burning WITH the glass on...
Do they "ghost" or lift off the burner?
If they do, it's a definite sign of a venting problem, but
you pretty much proved that by burning it with the glass off...
You either have a blockage in the venting or there's a disconnect
or a mismatch in the vent sections
allowing exhaust gases to re-enter the firebox.
I've seen it happen where the intake side of the DV pipe was connected,
but the exhaust wasn't fully seated/sealed...
The exhaust gases don't burn very well, since they're Oxygen depleted...
Take a pic of your cap & post it here.
It's probably one that one of us knows
something about & we might be able to talk you thru
the proper corrective actions after we see it...

 

[JFSanders]

Hello all, Jim here. Gas technician from Deland area of Florida.

Now for the OP.

Dasky has the most likely answer. There isn't enough fresh air getting into the combustion chamber to cool it off and the High temp switch is popping. If you look at the gas control there is a pair of usually black wires that go up the side of the box and connect to a dime sized button usually on the left side but could be on the right just about at the top. On some models it is on the top in the middle. Once the box cools enough the switch resets itself. Now running the unit with the glass off is a big no no. I would look at the joints in the vent. Most likely there is a gap in the exhaust side leaking into the fresh air intake side. This is hard to see and probably why the tech didn't see it. If the vent is put together correctly then your next check would be to see if they removed the insulation from the inside before they installed the vent pipe. It happens!

Jim

 

[Inside Guy]

Have you tried just turning the fireplace "down" a little bit, like turning the flame height to medium? If that works fine, I would probably say that it's a venting issue. By venting issue I'm refering to too much horizontal, not enough vertical. Sometimes they (mfg) sometimes try to get too many BTU's out of a stove/fireplace, whereas the amount of secondary air required to run the fireplace is insufficient to maintain a large flame. End result is the pilot starves out.

Hope this helps.

 

[CASS]

I have a similar problem with a DESA stove model # FSDVBNC. I have replaced everything except the pilot itself (gas valve, thermopile, thermocouple) and it will light and burn for a little while, then simultaneously it clicks and everything goes out. I did add a remote to it, and my next step will be to disconnect that and see if it will work without it in the circuit. What am I missing???

I should have mentioned that it will do this with the glass removed, so I don't think it is a venting problem.

 

[DAKSY]

Pull the pilot orifce out of the system & try blowing out the gas line.
i.e. Hold the pilot knob in & let the gas flow out of the pilot tube unrestricted by the orifice...
I've encountered situations where "gunk" (technical service term) in the
BIP gets up into the pilot orifice & stops the gas flow.
Once the gas flow stops, because of the low gas pressure, the "gunk"
drops down out of the orifice & lurks in the pilot tube til the next time someone tries to light the unit...
It doesn't take a very big piece of "gunk" to block a pilot orifice...

 

[CASS]

Thanks, I'll give that a try. By the way, what does BIP stand for? (I'm a newbie!)

 

[DAKSY]

BIP = Black Iron Pipe

 

[CASS]

Got it! I'm glad I asked because I don't have any BIP in my system. All copper and corrugated SS. But I did purchase it used from a guy who said he had trouble with the wind blowing out the pilot. My suspicion is that it was the problem I am experiencing and not the wind. Hopefully, clearing out the pilot tube will solve it. If not, I will be looking for more advice!

 

[CASS]

Well, blowing compressed air through the pilot tube didn't correct the problem. I did adjust the pilot flame to be a little bigger, in fact I could see the top of the thermocouple glowing red. With this adjustment, the pilot stayed lit all night and the fire came on in the morning because the remote t-stat called for heat. As soon as it reached the temp setting, the fire went out and so did the pilot! I relit the pilot and the same scenario repeated itself. It really acts like some sort of safety is shutting the pilot valve.

So, I put the remote switch to "on" instead of "remote" and relit the pilot. After turning the gas valve from "pilot" to "on", the fire came on (after a short delay) and burned for approximately 8 minutes and went out, pilot included.

Just to check, I have the thermopile wired to the "TPTH" and "TP" terminals on the gas valve, and the remote is on the "TPTH" and "TH" terminals. I assume this is correct?

 

[DAKSY]

Well, blowing compressed air through the pilot tube didn't correct the problem.

OK. That eliminates THAT idea...

I did adjust the pilot flame to be a little bigger, in fact I could see the top of the thermocouple glowing red.

Did you take a millivolt reading on the TP & THTP connections? Too high a setting will kill you thermopile...zYA wanna be between 550 & 600mv in most situations...

With this adjustment, the pilot stayed lit all night and the fire came on in the morning because the remote t-stat called for heat. As soon as it reached the temp setting, the fire went out and so did the pilot! I relit the pilot and the same scenario repeated itself. It really acts like some sort of safety is shutting the pilot valve.

It still sounds like a venting issue to me...The pilot doesn't use enuff O2 to starve the system, but with the burner on, the O2 depletion kills everything...

So, I put the remote switch to "on" instead of "remote" and relit the pilot. After turning the gas valve from "pilot" to "on", the fire came on (after a short delay) and burned for approximately 8 minutes and went out, pilot included.

Again, the burner used up ALL the O2 & when the pilot went out it took everything

Just to check, I have the thermopile wired to the "TPTH" and "TP" terminals on the gas valve, and the remote is on the "TPTH" and "TH" terminals. I assume this is correct?

Yep. That's the correct connection...

Have you taken a reading on the thermocouple (TC)? It should be putting out 25 - 30mv under the pilot flame - with the flame engulfing the top 3/8" of the TC...
If it drops down to less than 21mv, it'll close the electromagnets & stop the gas flow...

 

[CASS]

How do you check the mv of the thermocouple?

When I check the Tpile, it starts at 180 mv (on pilot) and spikes up to 216 with the fire lit, then starts dropping gradually to 150 and stays there until the safety shuts the fire off.

I tried it again, but this time I opened the glass a crack once the fire was going, and the Tpile dropped to 128 mv and held until I noticed that the swirling flame (windy outside) was burning the cloth cover of the Tpile wires! So I shut it off.

 

[DAKSY]

How do you check the mv of the thermocouple?

You'll hafta unscrew the connection where the T-C attaches to the gas valve.
Get yourself a pair of jumper wires with alligator clips on each end.
Attach one clip to each wire on your multi meter & one clip on the small silver colored end
of the T-C. Put the other clip somewhere on the copper section.
With the pilot on - you will have to hold the pilot button IN to keep the gas flowing -
take the reading...

When I check the Tpile, it starts at 180 mv (on pilot) and spikes up to 216 with the fire lit, then starts dropping gradually to 150 and stays there until the safety shuts the fire off.

That doesn't sound right. On the pilot you should be getting 550 - 600mv - NOT 180...
It should drop to 200 - 220mv with the burner on.

I tried it again, but this time I opened the glass a crack once the fire was going, and the Tpile dropped to 128 mv and held until I noticed that the swirling flame (windy outside) was burning the cloth cover of the Tpile wires! So I shut it off.

I'd replace that t-pile, but i'd be interested in what you get on the t-couple...

 

[CASS]

The Tcouple measures 25 mv with the pilot on.
The Tpile measures 171 mv with the pilot on.

OK, so I replaced the t-pile and it appears to have corrected the problem. It measures 198 mv with the pilot on, and goes to 460 - 500 mv with a fire. We used it last night and it was still on this morning and I know it cycled because we were at 39 degrees for a low (and it was nice and toasty in the bedroom).

I appreciate all your help on this. This is a great forum for those of us who insist on doing it ourselves! I will certainly recommend it to my DIY friends.

 

[DAKSY]

The Tcouple measures 25 mv with the pilot on.

T-coup could be a tad higher, but it should be ok...

The Tpile measures 171 mv with the pilot on

I'd replace it. True Value carries a universal unit for about $50...

 

[DAKSY]

Scuse my brain for not completely working here...
I was in the ER with my youngest daughter til 2 AM...kinda tired...
Before you replace the t-pile, did you try to increase the pilot?
There is an adjustment screw on the front of MOST valves which
will allow you to make adjustments...
Turn the screw while you are reading the t-pile...
Try to get it to read 500 minimum...
If you can't, then replace it...

 

[CASS]

The Tpile is the first thing I replaced. Did I get a bad one? Would a bad Tpile cause these symptoms?

 

[DAKSY]

The Tpile is the first thing I replaced. Did I get a bad one? Would a bad Tpile cause these symptoms?

It's possible you got a bad one, but even if it was bad, it has nothing to do with the pilot going out...
The only other contributor to a problem SORTA like this is in the Regency gas inserts
that have the 110v fan switch line running in close proximity to the low voltage switch wires.
In some units we had to wrap the fan switch & 110v wiring with electrical tape & try to get some distance between the 110 volts & the mvs...
Seems that the 110 volt field was sucking mvs out of the on/off switch wires.
We stumbled over this for months, changing out t-piles by the dozens...
Since we started with the wrapping the problem has been virtually non-existant...

 

[CASS]

Just what does the thermopile control? I don't have any 110V wires in close proximity to the t-pile wires, but I did unplug it from the outlet and it still went out after 17 minutes.

(hope all is well with your daughter)

 

[DAKSY]

Just what does the thermopile control?

A thermolpile is a millivolt generator. It is made of strands of dissimilar metals which
expand or vibrate at different rates when subjected to heat. This vibration or expansion causes a small
dc voltage (millivolt) to be generated. This voltage polarizes two small electromagnets which are
forced apart allowing gas to flow thru the opening. When the millivolts drop sufficiently,
the magnetic field cannot hold the magnets apart, & the gas flow stops.
When this happens, you can actually hear the "CLICK" of magnets coming together.
A thermocouple works EXACTLY the same way, it just generates a smaller voltage.

I don't have any 110V wires in close proximity to the t-pile wires, but I did unplug
it from the outlet and it still went out after 17 minutes.

Monitor your t-pile. It HAS to be dropping below it's minimum rating & that's why the gas flow is stopping.
The pilot going out is baffling, tho.
My thoughts are still leaning towards a venting issue...

(hope all is well with your daughter)

Thank you. She seems to be fine, but only time will tell.