Wood stove through a furnace chimney

[Char89]

Hey guys, I really need some expert input here! Bear with me, as I'm sure this has already been discussed at length in other threads.

So we have a chimney which has two fireplaces on it, plus it vents the oil furnace. We've been planning to get a woodstove for years, and about 3 years ago, had a masonry company come out to take a look- they advised it was best to put the woodstove in the fireplace, because it's an existing chimney.

This summer, 3 years later, we decided to order a stove from a different company, and had them come out and put chimney caps on- they took a look at our chimney then, and we reiterated that the furnace vented there.

Well we ordered the stove, put down a deposit, and waited months. They came today to install it.
They were about to put it in, when I again mentioned the furnace venting there. They freaked out, and questioned if we were really sure where the furnace vented. We showed it to them, and they said they can't run the woodstove through that chimney because of the furnace.

We've mentioned the furnace venting to 3+ other people at that company over the course of months, and they encouraged us to order the stove. We asked if they wanted to come out and look at the chimney more thoroughly before coming to install it, and they assured us it was fine as they'd already had a worker look when installing the caps.

What's the truth here? Is it ever ok to vent a stove through a chimney that vents the furnace? When we first discussed this with them, we think they were implying that they had a way to keep the fumes separate, everything would be contained. Who's right, and how did we end up finding this out the day of installation? I'm totally devastated. Anyone had a similar problem? Any simple solutions?

 

[bholler]

No you cant vent a furnace and a wood stove through the same flue. If it will fit you could vent it through a fireplace flue with a liner dropped through it.

 

[Jags]

Yeah - not Kosher to vent the furnace and stove in the same flue. It is a safety thing.
Maybe consider new pipe and a wood stove? Maybe different venting options for the furnace?? Just throwing ideas.

 

[Char89]

No you cant vent a furnace and a wood stove through the same flue. If it will fit you could vent it through a fireplace flue with a liner dropped through it.

The plan was to use an insulated liner through the chimney.. It's old mortar, so it's not 100% air tight. They told us there are two flues part of the way up, then it opens into one.
Would we need to divide the chimney all the way up, and still use a liner? Sorry if I'm painfully ignorant! I appreciate your response!

 

[Char89]

Yeah - not Kosher to vent the furnace and stove in the same flue. It is a safety thing.
Maybe consider new pipe and a wood stove? Maybe different venting options for the furnace?? Just throwing ideas.

Thanks! We have a second chimney that we aren't using.. it's about 15' away from the furnace. Maybe we could reroute it through that, by running piping along the cellar ceiling.. I'm trying to come up with the cheapest option, since we already bought the stove, a liner, and bio bricks.. Right now we don't have a plan B, and it's getting cold!
Will consult with our plumber & heating guy.. he might have some brilliant suggestions.

 

[bholler]

Ok i think we need a little more info. What is the existing chimney? It sounds like it is an old unlined brick chimney am i correct? If so the right way to do it is to drop a seperate liner for the furnace and the stove.

 

[Char89]

Ok i think we need a little more info. What is the existing chimney? It sounds like it is an old unlined brick chimney am i correct? If so the right way to do it is to drop a seperate liner for the furnace and the stove.

Yes- it's from the 1860s, and it's a brick chimney in rough shape. We were told we couldn't use it as a fireplace any longer because it's unlined- it would need to be rebuilt. The stove company told us that with the insulated liner, it would be fine to run the stove through it. We discussed the furnace venting through the chimney, and they said that was ok.
So we would need two of these liners, one for the furnace and one for the stove, then it would be ok? Maybe they can't fit both.. I didn't get a good explanation from them!

 

[AnalogKid]

I think some of the verbiage is confusing people. We are all in agreement that flue and chimney are two different things, right?

When the OP says "vents the furnace", I think there needs to be some add'l clarification. In the original post by Char89, there is no mention that the fireplace flue and furnace flue start off separate than at some point run into a Y-pipe, and continue up the chimney as one conjoined flue. In your second post you mention this.

Is it possible the initial 3-consults were under the impression that the fire place and furnace had dedicated flues, and not until install was it determined that they are conjoined? That's kind of what it sounds like.

Again, some of the verbiage and description may be tripping some folks up...?

If the fireplace and furnace do in fact have their own dedicated flues in the same chimney, I don't see why there would be an issue, as this is very common and many folks, myself included, have a woodstove in this scenario.

 

[bholler]

Yes that would be fine except that it is an old unlined brick chimney and both the furnace and woodstove should have a dedicated liner. Even if they are separate flues the furnace really should have a liner as well as the wood stove. If they in fact do join into one flue near the top which i have sen many times on old homes they absolutely need 2 liners to meet code and to function properly.

We have a second chimney that we aren't using.. it's about 15' away from the furnace. Maybe we could reroute it through that, by running piping along the cellar ceiling.

I seriously doubt that you can run 15' of connecter pipe horizontally for your furnace and you absolutely cant run it along the ceiling

 

[Char89]

I think some of the verbiage is confusing people. We are all in agreement that flue and chimney are two different things, right?

When the OP says "vents the furnace", I think there needs to be some add'l clarification. In the original post by Char89, there is no mention that the fireplace flue and furnace flue start off separate than at some point run into a Y-pipe, and continue up the chimney as one conjoined flue. In your second post you mention this.

Is it possible the initial 3-consults were under the impression that the fire place and furnace had dedicated flues, and not until install was it determined that they are conjoined? That's kind of what it sounds like.

Again, some of the verbiage and description may be tripping some folks up...?

If the fireplace and furnace do in fact have their own dedicated flues in the same chimney, I don't see why there would be an issue, as this is very common and many folks, myself included, have a woodstove in this scenario.

Hi, sorry about the verbiage-- I'm super upset! And ignorant about this stuff.
I have never known how many flues go up this chimney- which is what I told the company several times. We told them that the furnace vented through that chimney, and asked them to look at it. They had their guy look when they did the chimney caps, and they gave us the go-ahead to put a stove in there.
The guys who came to install it today told us there are two flues, which open into one higher up.
All the salespeople told us that it was ok to vent the stove and the furnace through our chimney, as long as we got the liner from them- this was also necessary because the mortar is in poor condition. When we actually placed the order, they checked with their guy who looked at our chimney, and said everything was good to go.

 

[bholler]

Yeah in that case you need a liner for each appliance as long as they will both fit (which they usually do on big old chimneys like yours) you will be in good shape other than having to buy a second liner. And make sure they insulate both liners

 

[Char89]

Yes that would be fine except that it is an old unlined brick chimney and both the furnace and woodstove should have a dedicated liner. Even if they are separate flues the furnace really should have a liner as well as the wood stove. If they in fact do join into one flue near the top which i have sen many times on old homes they absolutely need 2 liners to meet code and to function properly.




I seriously doubt that you can run 15' of connecter pipe horizontally for your furnace and you absolutely cant run it along the ceiling

Thanks- I'll scratch that fix off the list!
So I'll ask them about getting 2 liners when I talk with them tomorrow.. The two flues which join sounds like what they were trying to explain to us. Of course the two install guys were adamant that there is no solution. Thank you!

 

[bholler]

They may be seeing that there is not enough room for 2 liners but who knows they just may not have wanted to deal with it. At least they knew enough to not install it the way they had planned.although it is frustrating to you now it is better than having them do it wrong without saying anything

 

[Char89]

Yeah in that case you need a liner for each appliance as long as they will both fit (which they usually do on big old chimneys like yours) you will be in good shape other than having to buy a second liner. And make sure they insulate both liners

Thanks, you're brilliant. I just talked with them. They're really nice, but obviously the chimney wasn't checked really well ahead of time..
I just asked them about installing 2 liners. They say they'll have to do some blasting or something in the chimney, but it sounds like they do that stuff, and I'm hoping it's not too costly. So I guess the chimney isn't that huge, unfortunately. Which is probably why the install guys told us it was impossible.
I'll make sure to ask about getting both insulated- When we purchased the liner, they offered it uninsulated or insulated. We chose insulated because we don't have a tile liner.
I'm definitely handling this better due to your help, so thanks a bunch!

 

[bholler]

You are welcome i hope it all works out for you

 

[AnalogKid]

Hi, sorry about the verbiage-- I'm super upset! And ignorant about this stuff.
I have never known how many flues go up this chimney- which is what I told the company several times. We told them that the furnace vented through that chimney, and asked them to look at it. They had their guy look when they did the chimney caps, and they gave us the go-ahead to put a stove in there.
The guys who came to install it today told us there are two flues, which open into one higher up.
All the salespeople told us that it was ok to vent the stove and the furnace through our chimney, as long as we got the liner from them- this was also necessary because the mortar is in poor condition. When we actually placed the order, they checked with their guy who looked at our chimney, and said everything was good to go.

Yeah so they just basically assumed that there were two separate, dedicated flues for the fireplace and furnace, w/o doing proper due diligence (or actually listening to the homeowner!) until they physically got involved with the install. That's unfortunate and I understand why you are so frustrated.

Hopefully they will help you get everything worked out, good luck.

 

[Char89]

Yeah so they just basically assumed that there were two separate, dedicated flues for the fireplace and furnace, w/o doing proper due diligence (or actually listening to the homeowner!) until they physically got involved with the install. That's unfortunate and I understand why you are so frustrated.

Hopefully they will help you get everything worked out, good luck.

Thanks so much! I really appreciate you taking the time.
They're getting back to me with a quote for doing some blasting in the chimney.. Sounds like with some tweaks and two liners, it may be possible. The silver lining is that if they'd quoted the cost of the stove + blasting originally, I would've definitely said no! Now that the stove's there, and it's getting cold, I desperately want it installed..

 

[Char89]

You are welcome i hope it all works out for you

Thanks!