Incidental OAK?

[fireitup]

I know...asking this forum "to OAK, or not to OAK" is asking for a Hatfield and McCoy-type of response! Here's my query: Got a Breckwell P23 insert in a circa 1800 masonry fireplace, approximately 25' of SS liner to termination. Nice, new SS cap covering the entire chimney. NO chase cover (yet) on the terracotta, so the liner is just leaning against the side wall. Stove is running great at around 1/2 choke on the damper. The flue of course is wide open, with the 4" liner shooting straight up the middle. Figure it's best to install a chase cap to keep any POTENTIAL draft from coming down the flue into the hearth...or so I initially thought. I'm not getting any draft or loss of heat from around my surround, so now I'm thinking, wait a minute, IF any fresh air does manage to make its way down the flue into the hearth behind my already tightly-fit stove, isn't this really Outside Air that's being sucked into the stove by the combustion fan? Is this not a naturally good situation if I'm not seeing any negative affects in the house such as drafting or heat loss? So my question is not directly OAK, or no OAK, it's Chase Cap, or no Chase Cap. What say you, Stovemeisters?

 

[hossthehermit]

Personally, I'm in the "If it ain' t broke, don't............ ." camp .............

 

[alternativeheat]

I know...asking this forum "to OAK, or not to OAK" is asking for a Hatfield and McCoy-type of response! Here's my query: Got a Breckwell P23 insert in a circa 1800 masonry fireplace, approximately 25' of SS liner to termination. Nice, new SS cap covering the entire chimney. NO chase cover (yet) on the terracotta, so the liner is just leaning against the side wall. Stove is running great at around 1/2 choke on the damper. The flue of course is wide open, with the 4" liner shooting straight up the middle. Figure it's best to install a chase cap to keep any POTENTIAL draft from coming down the flue into the hearth...or so I initially thought. I'm not getting any draft or loss of heat from around my surround, so now I'm thinking, wait a minute, IF any fresh air does manage to make its way down the flue into the hearth behind my already tightly-fit stove, isn't this really Outside Air that's being sucked into the stove by the combustion fan? Is this not a naturally good situation if I'm not seeing any negative affects in the house such as drafting or heat loss? So my question is not directly OAK, or no OAK, it's Chase Cap, or no Chase Cap. What say you, Stovemeisters?

So you are telling us you have no block off plate to your chimney at the top or bottom with an old fireplace at the bottom? If so, you think you have no heat loss ?

 

[fireitup]

OK, some heat loss would be technically unavoidable, I agree, but it appears negligible. My surround is nice and flush, with only the slats in the surround to draw in room air for combustion. Am I mistaken in thinking that the majority of any outside air from above would be sucked in by the combustion fan? I'm thinking I'm good, considering how well the stove is performing, pellet comsumption is "normal", and my house is quite comfortable, so far running only on 2 setting of 5. I'm looking for experts to explain to me why I need to bother with a block-off or chase cap.

 

[alternativeheat]

OK, some heat loss would be technically unavoidable, I agree, but it appears negligible. My surround is nice and flush, with only the slats in the surround to draw in room air for combustion. Am I mistaken in thinking that the majority of any outside air from above would be sucked in by the combustion fan? I'm thinking I'm good, considering how well the stove is performing, pellet comsumption is "normal", and my house is quite comfortable, so far running only on 2 setting of 5. I'm looking for experts to explain to me why I need to bother with a block-off or chase cap.

Well I'm no expert but I've been burning stoves for more than 30 years. If you shut your stove off with the house warm so that the stove draws no room air at all then place a lit charcoal lighter, grill lighter, cigarette lighter or lit candle any where near the opening to the fireplace, any crack at all in a face board I think you will find the flame blows right into the fireplace opening with no block off of any sort. That equates to heat loss up your chimney. You are thinking in reverse, that cold air will enter your house down the chimney but chimneys draft warm air up naturally and very well. This is why we run OAK up past a block off plate or above insulation plates at the old smoke shelf. Two fold, the stove doesn't suck room air and neither does the chimney. I won't speak about the top, that just makes common sense to cap the chimney opening but I won't argue about it.

 

[fireitup]

Thanks Mate!, love the dog pics...Mastiffs? Hey Alt, wasn't trying to argue. With 30 years experience, YOU"RE one of the experts I'm talking about. I respect and take into consideration everything you guys have to say. I think a chase cap would be much easier to install than a block-off at the hearth flue. Although I'm not getting any water because I have a full cap installed, I will probably order a custom sized SS chase cap before the snow starts. I need a 9x18 with a 4" hole, and they appear to run around $100. That's a little pricey in my book (paid that for my clean-out tee), but it should last indefinitely, and make my setup more robust.

 

[fireitup]

Strewths, that's a big dog! Weighs more than me. I have a Newf puppy, Titan, he's 10 months and around 120lbs. Even full gown he'll only be 140-160. We love the big dogs. Actually, we like all dogs cuz they're dogs, but I prefer to own the big guys. My previous dog was a Berner named Jack, best dog I ever had. Titan is maturing nicely. Same temperament as Jack too.

 

[alternativeheat]

Thanks Mate!, love the dog pics...Mastiffs? Hey Alt, wasn't trying to argue. With 30 years experience, YOU"RE one of the experts I'm talking about. I respect and take into consideration everything you guys have to say. I think a chase cap would be much easier to install than a block-off at the hearth flue. Although I'm not getting any water because I have a full cap installed, I will probably order a custom sized SS chase cap before the snow starts. I need a 9x18 with a 4" hole, and they appear to run around $100. That's a little pricey in my book (paid that for my clean-out tee), but it should last indefinitely, and make my setup more robust.

I made my own out of aluminum.

I was not arguing but just making a point that house air will go up a chimney as well as stove air will . But once you put the plate up top it will stop that draft up and out the chimney and the flame test I mentioned will go neutral. However turn the stove on I don't care where in the chimney you put the OAK you will be drawing in room air unless you block off the bottom too, and allow an air passage to exist above the lower block off .

Using a top plate is also about blocking large amounts of cold air from surrounding the liner. You want the liner to run pretty hot.

And chickenman, that is one beautiful dog and a great photo comparing size with the little guy ! Pretty nice long lens you used too I might add.

 

[briansol]

Definitely cap it. and leave a spot for a 2" run down to the intake.

 

[Tim_M]

I have a similar setup with my Accentra insert, which is vented with a 25' x 6" liner up a capped chimney, no block off plate (I asked the installer about a block off and he said it wasn't necessary if the top was capped tightly). Anyway, at the back of my fireplace, just behind the insert and directly above the intake there is an ash clean out chute, about 18" deep that ends at a removable cover on the outside of the chimney. In the fireplace, the top of this chute was originally covered with a metal plate, but I thought "Why not remove that cover and drill some holes in the other outside cover to allow the stove to draw air up through this chute?" I'm not sure how effective this has been but everything seems to work well and I haven't noticed a lot of room air escaping into the chimney.