Wood stove and backdraft

[Casadecorgz]

Hi! My wife and I just bought our first house in Maine. We have a finished basement with a wood stove. We had chimney guys do work on our 3 flues including lining the basement wood stove with a stainless liner and insulation.

When I first light the wood stove, I do it slowly so I can get my system heated. Even then, I get probably 20% of the smoke backdrafted into my basement. Enough to make the basement gray and smell of smoke.

I have no windows down there, it adjoins to my utility room and garage.

I’m having an ERV system installed to hopefully balance out any negative air pressure and honestly I want some fresh air vented down there

What are others thoughts on this or have any recommendations on what I can do to prevent the backdraft especially if the ERV doesn’t help?

 

[begreen]

Would it be possible to bring in an outside air feed that terminates close to but not connected to the stove? It could have a valve to close it when the stove is not in operation. On some stoves, like PE stoves, the OAK does not directly connect to the stove air intake so the OAK has a built-in air break. For other stoves, the air can be terminated close to the stove intake but not connected. Or, could the OAK duct be run on the garage wall, or utility room wall, down low to the outside so that it stays below the firebox?

 

[Casadecorgz]

Would it be possible to bring in an outside air feed that terminates close to but not connected to the stove? It could have a valve to close it when the stove is not in operation. On some stoves, like PE stoves, the OAK does not directly connect to the stove air intake so the OAK has a built-in air break. For other stoves, the air can be terminated close to the stove intake but not connected. Or, could the OAK duct be run on the garage wall, or utility room wall, down low to the outside so that it stays below the firebox?

Wouldn’t the ERV do that? Sorry I’m new to home ownership can you explain OAK?

 

[stoveliker]

Also (as in the above are good.suggestions), I'd try to heat up the flue with a propane torch for a few minutes first to establish air flow in the right direction.

 

[begreen]

Wouldn’t the ERV do that? Sorry I’m new to home ownership can you explain OAK?

Yes, especially if the ERV is user-controllable for setting the air balance. Panasonic makes models that have this option.

Sorry, I thought you were also looking for alternatives. An OAK is an outside air kit.

 

[Casadecorgz]

Also (as in the above are good.suggestions), I'd try to heat up the flue with a propane torch for a few minutes first to establish air flow in the right direction.

Like put it inside the wood stove pointing up or heat the pipe in the back going into the flue?

 

[Casadecorgz]

Like put it inside the wood stove pointing up or heat the pipe in the back going into the flue

Yes, especially if the ERV is user-controllable for setting the air balance. Panasonic makes models that have this option.

Sorry, I thought you were also looking for alternatives. An OAK is an outside air kit.

Oh I definitely am! Do you have any materials you can send me or suggestions for outside air kits?

Are there any downsides to them? Like if I did it with the ERV

 

[stoveliker]

Like put it inside the wood stove pointing up or heat the pipe in the back going into the flue?

Yes.

 

[begreen]

If the stove always works well except for the period when the flue is heating up, then preheating the flue may be enough. Another thing that can help if the stovepipe turns 90º into the chimney connecting thimble is to change out the 90º to a pair of 45º elbows in an offset.

However, if the stove's combustion is poor even after the flue is warmed up, or if any smoke leaks as the fire dies down, then more air into the room can be worth it. Is there a CO detector in the stove room?

 

[begreen]

Oh I definitely am! Do you have any materials you can send me or suggestions for outside air kits?

Are there any downsides to them? Like if I did it with the ERV

What is the stove make and model?

 

[stoveliker]

Oh I definitely am! Do you have any materials you can send me or suggestions for outside air kits?

Are there any downsides to them? Like if I did it with the ERV

There should be no issue with a properly installed oak and erv. The oak creates a closed system: outside air into the stove, combustion, and smoke to the outside, regardless of the inside air pressure. And the erv makes sure the inside is either slightly over pressured or equalized to the outside, thus avoiding smoke roll out when the stove door is open during reloading.

It is important that an oak does not rise, but reaches the outside at or below the stove. Otherwise it might act like a chimney in draft reversal situations, and the pipe is not suitable to carry hot gases, only (outside) air.

 

[Casadecorgz]

There should be no issue with a properly installed oak and erv. The oak creates a closed system: outside air into the stove, combustion, and smoke to the outside, regardless of the inside air pressure. And the erv makes sure the inside is either slightly over pressured or equalized to the outside, thus avoiding smoke roll out when the stove door is open during reloading.

It is important that an oak does not rise, but reaches the outside at or below the stove. Otherwise it might act like a chimney in draft reversal situations, and the pipe is not suitable to carry hot gases, only (outside) air.

Is an OAK something I could do or would I need a chimney company to do it?

 

[stoveliker]

If you can make the hole in the wall, you can do it.

 

[Casadecorgz]

What is the stove make and model?

I do have a CO detector down there now. It came with the house so I’m not sure, it says Defiant on the side with a photo attached

It does smoke a little back into my home even after everything is heated

 

[Casadecorgz]

If you can make the hole in the wall, you can do it.

do you have a referral for one or equipment I should buy?

 

[yooperdave]

Wouldn’t the ERV do that? Sorry I’m new to home ownership can you explain OAK?

Your ERV should be (might be) hooked up to your ductwork. It'll exhaust the stale air from bathrooms (for example) but reclaim some of the heat in that air before exhausting it to the outside. The incoming "fresh" air will absorb some of that heat before it is distributed through the ductwork to replace the exhausted air. this process does not create a positive or negative pressure in the house if connected and maintained properly.

The addition of an OAK should help with the backdraft greatly. A 4" hole bored in the rim joist connected to a 4" flexible insulated "duct" (like a dryer hose kinda) run to the area of the stove, At that point, it is tied into the stove. You want to use insulated flex to avoid the occurrence of condensation when drawing in the cool air from outside to the warmer inside air.

 

[begreen]

The old Defiant did not have an outside air connection. If you look at the stove's flue path, you will see that the smoke has to make 3 90º turns just to get out into the chimney. That is slowing down the draft quite a bit which is exacerbating the situation.

The paper labels should be removed from the stovepipe.

 

[begreen]

The addition of an OAK should help with the backdraft greatly. A 4" hole bored in the rim joist connected to a 4" flexible insulated "duct" (like a dryer hose kinda) run to the area of the stove, At that point, it is tied into the stove. You want to use insulated flex to avoid the occurrence of condensation when drawing in the cool air from outside to the warmer inside air.

It can not be tied to the stove if the air feed is above the firebox due to the possibility of reverse drafting and the duct becoming a chimney. Imagine what would happen if the duct was plastic. The duct could terminate a few inches behind the flapper intake on the stove.

 

[yooperdave]

The old Defiant did not have an outside air connection. If you look at the stove's flue path, you will see that the smoke has to make 3 90º turns just to get out into the chimney. That is slowing down the draft quite a bit which may be exacerbating the situation.

The paper labels should be removed from the stovepipe.

You'll be reminded if you forget to remove those labels the first time you fire up!

 

[Casadecorgz]

The old Defiant did not have an outside air connection. If you look at the stove's flue path, you will see that the smoke has to make 3 90º turns just to get out into the chimney. That is slowing down the draft quite a bit which is exacerbating the situation.

The paper labels should be removed from the stovepipe.

So would you recommend I start with changing the flue path? Given the height of the stove to the flu, is that going to be a problem? Or would you recommend I go with a OAK first?

 

[begreen]

Casadecorgz is the bypass open when starting the stove? This is a downdraft stove. It needs to get warmed up nicely to draft well before closing the bypass.​

 

[yooperdave]

It can not be tied to the stove if the air feed is above the firebox due to the possibility of reverse drafting and the duct becoming a chimney. Imagine what would happen if the duct was plastic.

Absolutely. Do not run the insulated flex right up to the stove. Poor explanation on my part!

A well placed backdraft damper can work wonders with the OAK.

 

[Casadecorgz]

Casadecorgz is the bypass open when starting the stove? This is a downdraft stove. It needs to get warmed up nicely to draft well before closing the bypass.​

Sorry, which part is the bypass. Is it on the stove or the lever on the flue pipe?

 

[begreen]

So would you recommend I start with changing the flue path? Given the height of the stove to the flu, is that going to be a problem? Or would you recommend I go with a OAK first?

The first thing I would try is moving and rotating the stove to where there are only two 45º turns in the stove pipe entering the chimney. It may need to come forward a bit to accomplish this.

 

[begreen]

Sorry, which part is the bypass. Is it on the stove or the lever on the flue pipe?

No, that is the stove pipe damper. It is very possible that you don't need one at all. It too will slow down draft a bit, even when wide open. I'd remove it when reconfiguring the stovepipe.

The stove has the bypass damper lever on the left side. I think the bypass is open on the Defiant when that handle is horizontal and closed when it is vertical.

Is there a 1.5" deep layer of sand on the floor of the firebox? This stove must have that before burning in it.