Weird smell at 650f and above

[SculptureOfSound]

Ok guys, I'm at a loss...

I installed my insert (a used VC Montpelier) about 3 weeks ago. now whenever I burn it hot (650-700 stove top) i get a strong smell that is like burning dust + hot metal. At first I thought it was the paint, then I thought it might be the roxul (used around liner and on sides and back of insert) off gassing, but after 6 fires (probably 20 hrs burn time at 600 or above) the smell still comes back whenever burning hot. It builds up over time and within 30-60 minutes it is really strong and we have to open windows and/or leave.

Any idea what it could be? Some thoughts of mine:

Stove cement i used to seal liner to insert and liner joints (i used rigid oval duraliner, with a 3 foot section of oval flex and an oval to round flex piece to hook to the stove). I used meecos gasket/stove cement from fleet farm, rated to 2100 degrees

Some creosote on smoke shelf? I cleaned it prior to install but did not do as thorough a job as I could have. If this were the issue I would think burning for hours at say 500 stove top would bring the smell too, but it doesn't seem to. Smell only comes at around 650 and up

A leak from the insert? The Montpelier is a cast iron insert (gasketed), maybe there's a leak (this seems unlikely as it should smell more at lower temps with weaker draft...smell is only when it's hot).

Wrong paint used by previous owner either on the insert or surround? I didn't repaint the surround. It didn't look like they had ever repainted the insert but it's hard to say. No idea how I could know if they repainted or if an incorrect paint was used.

The stove bright paint i used to repaint? this seems unlikely as I pushed The insert to about 750 once, but the smell came back today once it hit around 650. so far it seems The smell always starts building up once it hits 650.

The duraliner. Not sure what would smell although there have been other threads about weird smells and it seems many used duraliner. Maybe the outer galvanized wall is getting too hot and off gassing. There was an oil of some sort on the flex and the oval adaptor but at should have burned off in 20+ hours, right?


What are your thoughts? I'm not sure what I can do to experiment/test at this point. It's getting real old having to open all the Windows in 30 degree weather and even leave the house taking our one year old out of God knows whatever those fumes are.

 

[JA600L]

Don't worry about it yet. Give it some time and see if it improves. It always takes a long time to get rid of fumes when you hit high temperatures.

 

[SculptureOfSound]

And JA600L..so paint can really keep off gassing even when not hitting a new hi temp?

Btw here is a link to what I used on the oval adaptor piece connecting the liner to the stove. I could see light between the inner crimped piece and outer piece of the adaptor so ran a thick bead of the sealer in there before attaching to the flue collar. quite a thick bead.

https://www.menards.com/main/heatin...stove-sealer-10-3-oz/110c/p-1444439440229.htm


Maybe someone can look at that SDS and let me know if that might be it? Thought it would be ok to use as it says it is ok to use on stove and pipe cracks/leaks.

 

[SculptureOfSound]

I'm considering taking a heat gun to the front to see if that's the issue (i didnt even repaint the top, just a small portion of the top that is visible from the front). anything i should consider before doing this - i don't want to ruin the paint job or cause warping or something due to a very localized heat source

 

[begreen]

How and where are you measuring stove top temps on the insert?

 

[SculptureOfSound]

IR gun into the air channel. If I aim it just right I can hit part of the stove top that goes up as a lip or sidewall to the air channel. This lip is part of the stove top.

I'll post a pic later of the Montpelier to show what I mean. I've run it with the surround off too and measured stove top directly (there is a portion around flue collar where the stove top is exposed and not covered by the convective jacket.)

If you look at the parts diagram in the Montpelier manual it will make sense. Kind of a different design than any other insert I've seen.

 

[SculptureOfSound]

Here's what it looks like with the sheet metal convective jacket off. Note I didn't even repaint the top, just the front really.

So I can hit with the lip with the IR gun easiest on the right side..the left side is hard due to the air slider.

 

[xman23]

Do you need to run it at 650 to heat the house? I think most of us will get some smell at that temp. Normally just a new high temp smell and not enough to open the windows. Whenever I smell that, it's time to close off the air and cool her down a bit. You may not be overfiring it, but constant temps that high got to be hard on the stove.

 

[SculptureOfSound]

No I don't normally need to run it that hot although it is pretty easy to get it that hot with a full load (even with the air all the way down, mostly have pine to burn ATM) and I'd hate to have to run with just a few splits at a time to keep it cool enough not to stink.

This smell becomes quite potent and is enough to require the windows be opened and even then it takes time to dissipate. It's not (imo) within he realm of a normal operating smell as nobody would burn wood if it was.

Curious as to any ideas what it could be - something I listed above or something else? Also curious as to any tests or experiments I could do.

Btw what you see in the pic above is after repainting. so almost no paint on the top. Also, just FYI the sheet metal top is kind of U shaped, it sits over the air channels on the left and right but does not cover that middle section where the flue collar is.

 

[SculptureOfSound]

Oops just looked at the pic again, it's not after repaint but my new paint lines are about the same as the old. Just a few inches up onto the front of the top

 

[SculptureOfSound]

So I'm trying to think of possibilities be other than something off gassing with high temps... Maybe some leakage of smoke that has already been through secondary combustion? Maybe the heat is causing expansion issues and smoke is leaking out at the door or flue collar? (flue collar on he Montpelier is removable and sits on a gasket). Is that plausible?

 

[begreen]

IR gun into the air channel. If I aim it just right I can hit part of the stove top that goes up as a lip or sidewall to the air channel. This lip is part of the stove top.

I'll post a pic later of the Montpelier to show what I mean. I've run it with the surround off too and measured stove top directly (there is a portion around flue collar where the stove top is exposed and not covered by the convective jacket.)

If you look at the parts diagram in the Montpelier manual it will make sense. Kind of a different design than any other insert I've seen.

The reason I asked is that the temps you are reading may be on the low side. Closer to the flue collar the stove may be getting much hotter. What you are describing sounds like that hot metal smell that often precedes or accompanies overfiring. If it happens again and it is night, turn out the lights and look through the vent toward the flue collar. If it is glowing dully then the stove is too hot.

 

[SculptureOfSound]

I'm going to pull the surround before my next test burn and check temps at all areas of the stove top and also the external liner temps. Hopefully that might shed some light on things.

Begreen, what temp would you say that smell normally starts to appear at and how strong is the smell? Is the temp different for cast iron vs steel?