Smoke from pellet stove vent

[Lilje]

We recently moved a pellet (Quadrafire Mt Vernon) stove from our main living room into our basement. Since the move, every time it starts from cold, smoke seeps out from every joint in the line. How do we stop this? It did not do this when it was upstairs.

 

[DAKSY]

Tape the seams with aluminum tape or take each individual piece of venting apart
& apply RTV silicone in the joint area before re-assembling.
In the original set-up, the seams may have gotten sealed with fly ash...

 

[jackman]

I'll second Daksy. I use foil tape on all my seams then use a stove spray paint it if necessary.

 

[corkman]

We recently moved a pellet (Quadrafire Mt Vernon) stove from our main living room into our basement. Since the move, every time it starts from cold, smoke seeps out from every joint in the line. How do we stop this? It did not do this when it was upstairs.

This is all I use. Easy to apply and easy to remove when needed. I do have black pipe so it blends in well and no need for paint with this stuff. Home Depot has it in plumbing aisle.

 

[zrock]

This is all I use. Easy to apply and easy to remove when needed. I do have black pipe so it blends in well and no need for paint with this stuff. Home Depot has it in plumbing aisle.

you do realize that stuff is highly flammable? This is why alum tape and stove specific RTV is always recommended

 

[Oregun]

you do realize that stuff is highly flammable? This is why alum tape and stove specific RTV is always recommended

Looks like that tape is rated to 500F.

 

[johneh]

Don't know about your pipes but mine have never been near 500
with the stove going full I can still leave my hand on the pipe
mind you a full-tilt it gets very warm to the touch but only around 150 deg
I have used that tape don't like it but have used it

 

[Oregun]

I use JBweld RTV ultimate black for two of the seams in my 6" single wall pipe. This has a temp. rating up to 500F also.
I think my pipes can get up 300F during normal operation. But I guess worst case would be during a chimney fire though rare with pellet stove which would exceed 500F I am sure.
Johneh what don't you like about the tape?

 

[johneh]

Johneh what don't you like about the tape?

Tried it a couple of time could never get it to work right maybe just my big fingers
I like the metal tape harder to get off but seals well and paintable

 

[Oregun]

Just looked up three different 3M metal foil tapes. Max temps were 250F-300F.
This one -> 3M #433. goes up to 600F.
It is not cheap.

 

[johneh]

The stuff I use is industrial for the solar industry
Have 2 cases left from when I worked solar
Don't even know if 3M makes it now

 

[Lilje]

Thank you all very much for the suggestions. However, I think I didn't explain the problem well enough. It is not just leaking at the vent piece joints, but at every spot in the pipe where there is a joint. For example, where each individual piece of metal in the elbow meet. It also leaks out between the inner and outer pipe at the appliance adapter. So I think smoke is somehow getting out of the inner liner and into the outer space. Will sealing the joints work either silicone or tape fix this?

 

[Ssyko]

time to replace the pipe sounds like it is perforated inside

 

[Tiggar61]

Did you screw sections together? If screws are to long it will ruin inner liner.

 

[kappel15]

I use high temp clear caulk. Has always worked. Also use the alum tape too. Both are good. kap

 

[SidecarFlip]

I use high temp clear caulk. Has always worked. Also use the alum tape too. Both are good. kap

Yep. Myself, I use Red High Temp RTV. Sounds to me like it's time to re-vent. Far as a chimney fire in a pellet stove, sounds like a fantasy. Only thing a pellet burner emits is fly ash and carbon dioxide from the exhaust unless you burn corn like I do, then you get nitric acid vapor from the corn and it eats the stainless liner after a decade or so. Just replaced a couple sections on mine after 15 years. Got some small holes on the outside run. Mine comes completely apart every spring and I pressure wash the venting inside with Purple Power and high pressure water to clean the crap out.

My venting (between the appliance and the wall thimble will reach 450-500 degrees when it running hard. Outside, maybe 250 on the lower vertical sections.

I hardly ever get any 'smoke' except on initial startup. By 'smoke' do you mean wood smell maybe?

 

[SidecarFlip]

Did you screw sections together? If screws are to long it will ruin inner liner.

Big no screwing sections together. Fine for wood stove single wall pipe. Big no for pellet venting. Pellet venting is all twist lock, no screws required or needed as the space between the inner stainless liner and the outer galvalume shell is small, about 1/4" maximum.

On my outside sections, before I assemble them, I coat the mating flanges with never seize. Makes taking them apart (for cleaning), much easier.

 

[rickwai]

Yep. Myself, I use Red High Temp RTV. Sounds to me like it's time to re-vent. Far as a chimney fire in a pellet stove, sounds like a fantasy. Only thing a pellet burner emits is fly ash and carbon dioxide from the exhaust unless you burn corn like I do, then you get nitric acid vapor from the corn and it eats the stainless liner after a decade or so. Just replaced a couple sections on mine after 15 years. Got some small holes on the outside run. Mine comes completely apart every spring and I pressure wash the venting inside with Purple Power and high pressure water to clean the crap out.

My venting (between the appliance and the wall thimble will reach 450-500 degrees when it running hard. Outside, maybe 250 on the lower vertical sections.

I hardly ever get any 'smoke' except on initial startup. By 'smoke' do you mean wood smell maybe?

I finally replaced the outside 2' piece of PelletVent Pro from 2008 with another used piece I had on hand. I got ready to throw my rusted off corroded thru piece (corn) then thought, Wonder if Simpson will replace it? I took a couple pics and wrote a short explanation (basically burning corn) and same day they replied with the reason it corroded thru and said we will ship you a new piece and a termination cap free of charge! I did not request a term cap. I use a 3" z-vent screened tee, It friction fits the inside diameter of the pipe. Seems like with a standard term cap it wants to build moisture/acid in the joint and starts rusting the galvanized quickly.

 

[SidecarFlip]

I finally replaced the outside 2' piece of PelletVent Pro from 2008 with another used piece I had on hand. I got ready to throw my rusted off corroded thru piece (corn) then thought, Wonder if Simpson will replace it? I took a couple pics and wrote a short explanation (basically burning corn) and same day they replied with the reason it corroded thru and said we will ship you a new piece and a termination cap free of charge! I did not request a term cap. I use a 3" z-vent screened tee, It friction fits the inside diameter of the pipe. Seems like with a standard term cap it wants to build moisture/acid in the joint and starts rusting the galvanized quickly.

My trick. if you want to call it that to extend the life of the venting as long as possible and mitigate the corrosive effects of the nitric acid vapor is, at the end of the heating season, a week or so before I shut down the appliance for it's annual tear down and maintenance, I switch to 100 % pellets and run only wood pellets for a week or so, on high feed rate at least part of the time anyway (if we can stand the overheated house a while)... That drives off any of the accumulated nitric acid that might be lingering inside the stove and the venting and then I take the venting apart over the summer and wash it inside with Purple Power and my pressure washer. Like I said previously, 15 years on this venting and I just replaced one section that had a small rust hole in the Galvalume exterior pipe. Yr was the 3-4 transition Tee with the cleanout which I remove regularly and dump the fly ash so I'm thinking the removal and replacement of the cleanout cap might have contributed to the corrosion issue. Of course I apply Never Seize to the joint so I can get it apart easily.

Keep in mind too, that I don't burn straight corn either. I mix my corn with pellets at a 3-1 ratio, 2 parts corn to one part pellets. That eliminated the corn clinkers for me almost entirely and the corn I run is dried below the 12%RM standard as well I dry it down to 10%. The drier it is, the better and hotter it burns. and that is something I can control, being a farmer.

I never clean it either. It goes from the field to the dryer to the grain tank to my stove. Years ago I cleaned it and checked it for stray metal parts but with the advent of axial flow combines, the chance of any 'stray parts' from the machine are basically nil so no point.

 

[rickwai]

My trick. if you want to call it that to extend the life of the venting as long as possible and mitigate the corrosive effects of the nitric acid vapor is, at the end of the heating season, a week or so before I shut down the appliance for it's annual tear down and maintenance, I switch to 100 % pellets and run only wood pellets for a week or so, on high feed rate at least part of the time anyway (if we can stand the overheated house a while)... That drives off any of the accumulated nitric acid that might be lingering inside the stove and the venting and then I take the venting apart over the summer and wash it inside with Purple Power and my pressure washer. Like I said previously, 15 years on this venting and I just replaced one section that had a small rust hole in the Galvalume exterior pipe. Yr was the 3-4 transition Tee with the cleanout which I remove regularly and dump the fly ash so I'm thinking the removal and replacement of the cleanout cap might have contributed to the corrosion issue. Of course I apply Never Seize to the joint so I can get it apart easily.

Keep in mind too, that I don't burn straight corn either. I mix my corn with pellets at a 3-1 ratio, 2 parts corn to one part pellets. That eliminated the corn clinkers for me almost entirely and the corn I run is dried below the 12%RM standard as well I dry it down to 10%. The drier it is, the better and hotter it burns. and that is something I can control, being a farmer.

I never clean it either. It goes from the field to the dryer to the grain tank to my stove. Years ago I cleaned it and checked it for stray metal parts but with the advent of axial flow combines, the chance of any 'stray parts' from the machine are basically nil so no point.

I usually try to burn pellets at the end also. There are years I dont. I try to clean the stove and vent good then burn pellets thinking the wood ash will neutralize the acid. I burn straight corn 100-125 buu/season. I do screen mine to get the fines and bees wings out to help keep the house clean. With the St. Croix clinker drop system no need for pellets. I have run mine for weeks at a time without shutting it down. This stove does not burn straight pellets very well. The carbon will build up on the pot bottom/slide and want to stick. I really likes corn best.

 

[SidecarFlip]

I usually try to burn pellets at the end also. There are years I dont. I try to clean the stove and vent good then burn pellets thinking the wood ash will neutralize the acid. I burn straight corn 100-125 buu/season. I do screen mine to get the fines and bees wings out to help keep the house clean. With the St. Croix clinker drop system no need for pellets. I have run mine for weeks at a time without shutting it down. This stove does not burn straight pellets very well. The carbon will build up on the pot bottom/slide and want to stick. I really likes corn best.

I get hard carbon buildup in the bottom of the firepot as well (pellets and corn) but I have 2 burn pots so one is soaking in a bucket of water while the other is in the stove. When it comes to clean time, I just switch pots and the one that was soaking, all the hard carbon is loose and I use a small putty knife to clean it out.

Been doing that right along.

So warm here as of late, no need to have a fire. The central furnace takes the chill off in the AM and that is it for the day.