Smoke smell from Harman Acentra

[cooler]

My approx 8 year old Harmen Acentra has a smokey smell, which started last year. I have replaced and I have had the dealer replace the exhaust pipes, observe it, reseal exhaust. I'm pretty sure the exhaust has been taken care of.

The smell is still there. I have checked and taped windows in the house, anything I can think of. I have replaced the door gasket and looked at the others. I don't see any smoke, but I smell it.
Dealer says the heat exchanger can't leak to room because of the negative pressure caused by combustion fan. I understand this general concept but is that too broad a statement? We are missing something. Have you seen (smelled) anything like this? Any ideas to try? thanks much!

 

[Bioburner]

What about the venting thimble? Has it been seal outside the house to prevent some exhaust from coming in? Still lots of possibilities. Stove have an OAK?

 

[johninwi]

One trick others have used is a flashlight in the dark, might be worth a shot. The installers that did my stove had a hand held CO sniffer/detector, they were able to check each seam with it and resealed a few spots, ask your dealer if they have one or call around and find a dealer with one.

 

[Bioburner]

I saw a hand held gas detector at a box store for less than $30. I have one that I used to track down a propane leak. Was worth the $$ considering that a visit by a pro is twice that.

 

[cooler]

thank you all for the replies.

Bioburner - Yes, it has been sealed and resealed all around the thimble area, inside and out. The pipes have been sealed entering and leaving the thimble and the perimeter of the thimble has been sealed. I think the dealer is good on this part, and we have basically done it all two times, on the orig vent pipes, and on the new set of pipe$. Also the stove does have outside air and the damper inside the stove was removed. The place where the inlet pipe meets the stove has been well taped with metal duct tape as well.

Johninwi - I read about the flashlight idea and did try that out. I have not been able to see any smoke. CO detector is a good idea, dealer didn't seem to have one but I may have to follow up on this.
One more thing - reading in this forum last night I saw 2 possible ideas to try too. One is to start stove and get to the full smoke phase just before flame, then shut the stove off, see if stove leakes anywhere (it is vented straight out back of stove with about 2+ feet of pipe, that's it - or do same thing, pull the plug at full fire. Second idea was to throw some wet pellets directly onto the fire to get smoke that way.

 

[cooler]

I did a quick test. I started the stove up to full flame, then pulled the plug. Within a minute or so Ihad smoke coming out around the door, top and bottom - mostly from the bottom. Is this expected without the comb fan blowing, or is this my problem?

 

[Mt Bob]

Well stove door gaskets rarely an airtight seal,but are cheap to replace.It tells me you have no natural draft also.Post some pictures of your install and flue so others can help.Also be aware your house may have changed/shifted etc,and if house has a negative draft could be sucking in a small amount,you would never see it but could smell it.

 

[cooler]

I have replaced the gasket for what its worth but the door may still be too loose. It is approx 2" OA in pipe (sealed to stove with fresh metal tape) about 8" above the straight out 3" exhaust pipe. The exh is straight out the wall, only 2 - 3 feet of exh pipe total. House is tight but boiler has full outside air intake, no other fans etc on. Dryer used rarely but this happens all the time without dryer.

 

[Mt Bob]

Well for what it is worth(and people will prob. disagree) it is possible that with the room blower on,blowing air across the top of the door,it could siphon a small amount of fumes out,nothing visable.Not much adjustment in acenntra doors,but you will see almost all the parts places on the net sell the latch assembly.It is mild steel and the little ramps wear.Maybe try a new door gasket and new latch and let us know?

 

[Mt Bob]

http://www.stove-parts-unlimited.com/Accentra-Door-Latch-Bar-p/2-00-247175l.htm

 

[cooler]

Yes, at $11 that would be worth a try. I had played with this latch a little already trying to make it tighter, I think there is a little play in it. Also I did replace the gasket but the new one wasnt any tighter than the old one. I am thinking like you, I know its negative pressure and all but as you say there are other forces at work too...

 

[Bridgeman]

The manual says I needed a 1/2" seal but the reality was a 5/8" seal was a much better fit in my Accentra. I attribute the variance to the loose weave of the after market gasket. I doubt that's your problem however. I think it is on the exhaust side somewhere. It could also be something as simple as the seams of the house opening up due to the long cold and dry winter and letting some small amount in near the exhaust vent.

 

[corkman]

Is your oak above your vent on the exterior. If so then that's a no no

 

[cooler]

Yes, OA inlet is above vent about 6-8" on center. This is how the thimble is setup, however the dealer may have drilled the hole for the oa inlet himself. However...it worked fine for maybe 6 years like this, then last spring something changed and I started getting the smell. House is pretty tight with spray foam insulation in most of it and interior storms on the windows.

Talking about the oa intake above the exhaust, seems like it has more potential to pull some smoke back into stove, but the inlet is sealed to the stove with good metal tape. I was concerned about this myself and earlier I removed the oa intake and tried the stove on room air, like the dryer has to use. Seemed the same. At that time the stove still had the internal damper to close on the oa opening when no fan running. That damper was pulled out by dealer on last visit.

Bridgeman, it is still possible it is the exhaust but a lot of effort has been expended in that direction, that's what the dealer thinks too, but they can't find anything. I am looking at things they are ignoring, latest idea is the sort of loose door (they agreed with you that because of negative pressure, nothing should escape there). I think there may be some interactions, like that brought up by Bob B above. Do you know what I would look for to find that 5/8" gasket material?

I'm open to other ideas, a few days ago I masking tape'd closed a bunch of windows just to check if anything was getting in there, no difference.

 

[Mt Bob]

There are thimbles made with the oak above the flue hole,but the flue is supposed to go up after it goes out so it is above the oak.If you do this there will be less chance of smoke in the house in a power outage.Corkman is right,never above.

 

[Bridgeman]

I picked up this at the local Ace Hardware. They also sell online for $12 and that includes the cement.
I dampen with a wet paper towel and stretch it just a bit to stiffen it on the instalation. It helps to put the seam at the top. The trimming is a lot less trouble that way.

 

[cooler]

I guess the question I need to answer now is, Is it surprising to get a lot of smoke out of the stove door, esp. at the bottom, very quickly after killing power to the stove? This means basically, the door "seal" is the weakest link, the first place smoke leaks from the stove in this test.

If you think this is normal for a stove with a straight out the back pipe, let me know. I won't waste the money on a thicker gasket and new door latch.
thanks for your opinion.

 

[bogieb]

I don't think it is abnormal for a stove that is straight vented to leak around the door edges when the plug is pulled. My Hastings leaks like that at loss of power (it has about a 1' rise - otherwise it is all vertical).

 

[Mt Bob]

I guess the question I need to answer now is, Is it surprising to get a lot of smoke out of the stove door, esp. at the bottom, very quickly after killing power to the stove? This means basically, the door "seal" is the weakest link, the first place smoke leaks from the stove in this test.

If you think this is normal for a stove with a straight out the back pipe, let me know. I won't waste the money on a thicker gasket and new door latch.
thanks for your opinion.

Yep that is gonna happen with your install.Other stoves would leak around glass,as some have a gap for air wash.Almost all stoves will leak around combustion blower,as there is not a positive shaft seal because of heat.

 

[cooler]

OK, maybe the amount of smoke I'm seeing is higher than normal, not sure. Will think about the door seal as I look for any other issues to check. Thanks for all the ideas and info

 

[Mt Bob]

We(you) started off with a smoke smell,progressed into bad smoke when stove shut off(power outage).You have already said your install does not meet code,you have shown no initiave(sic) to even to consider.Quit wasting peoples time if you do not want to do a proper install!

 

[cooler]

I didn't say it doesnt meet code. Are you saying it doesn't meet code because the oa is above the vent? If so, do you think if I change this the smoke smell goes away - I have already tried the stove without outside air, a legitament arrangement, and I have mentioned that it has worked without a smoke smell and this setup for 6 years. Also, the oa feeds into the already smokey chamber, does it matter if a slight amount of smoke is brought into that?

I am open to your best opinion of what might improve the smoke smell. If you think moving the outside air has a good chance, I will consider that. I guess I am trying to get a few good ideas before I try my next fix. I do appreciate the ideas!

 

[Bioburner]

Manual suggests to have several feet of vertical venting to prevent or minimize power off smoke issues. You could also have smoke entering house through soffits.

 

[cooler]

I am thinking about a test for a couple of these possible causes, smoke getting in oa inlet, or soffit or other places into the building. What if I temporarily added several feet of pipe to the horizontal install, push the smoke further away from house and oa inlet. If that made a difference we could see how best to change the piping permanently

 

[cooler]

I ordered a new latch, I'll start with that and possibly the thicker gasket Bridgeman is using. Will see if that makes any difference in the no power smoke test for starters. Thanks for your ideas!