High Draft with Small Stove. Replace or Repeat?

[Egbert Souse']

Hello all. First off, I'd like to thank everyone that makes this place a wonderful and knowledgeable space to read. I've learned much but feel there's much more to absorb.

Last January, I had a Hearthstone Craftsbury installed with venting. Almost 25ft of Class A chimney outside and 3 to 4 ft of double wall coming out of the stove top to a 90 which goes into the class A with a cleanout tee. I would like to add that within 2 weeks of delivery of the stove, my catalyst bypass gasket fell out. After my installer consulted his contact at Hearthstone I was told this was unnecessary. Just a cushion for the door. Not sure how to feel about this or what effect if any this has on my draft.

The heat output of the stove is great for our small (1200 sq ft) home and I enjoy watching the actual fire itself. With the correct wood species and load size this stove can keep my main floor and upstairs heated nicely with fans strategically placed to move air. Aside from the short burn times and difficult task of loading up and not overfiring, I enjoy the stove. Plus, it looks great in the middle of my main living space.

I have gone through nearly two winters with this stove and while I haven't had a proper draft reading taken yet, my draft is quite strong. I've installed 2 separate key dampers in my double wall to tame the draft. One is a stove pipe adapter unit and the other one is the innards of a second stove pipe adapter damper that have been fashioned into the pipe to fit above my thermometer. I wanted to ensure the dampers were both the correct size.

If the stove is loaded full and the temperature cold, it takes both dampers closed fully to keep the stove from over firing. The air control used without the dampers in this situation simply switches the combustion from the primary doghouse air inlet and some secondaries, to primarily the secondaries which look like acetylene torches shooting flames up past the baffles. It's a bit unsettling. Especially when I see videos of others with their lazy flames on fully loaded stoves.

If I were to burn only 2-3 splits at a time however, the fire is less vigorous and I can use less damping (or even none if it's over 32F) and the air control is more usable. But, in this situation I am wed to reloading the stove every 90 minutes to 2 hours as the absolute best case scenario. With mine and my wife's work schedules and the cold winter we've had, this simply isn't reasonable. When I load the stove up to attempt a long burn for which I'll be away, there's always the thought in the back of my mind that the stove will get out of contol and I won't around to do anything about it.

I have burned many wood species in the stove. I've tried using larger splits as well to keep from over firing. But with the small door opening and the length of seasoning time of "good" wood, I haven't had the absolute best quality wood. Dry, yes, but not species I love other than the large quantity of Ash I had. So far I've used all my "good" wood IE Red Oak, Beech and hard Maple only overnight so I can at least wake up with some coals to relight the next morning.

My question is, would replacing my stove with a larger unit that can fit more wood and require less "stuffing" full to get longer burns actually yield a longer burn or would it just heat us out of the house? I am curious about some of the soapstone walled Hearthstones but they might be too large. With my limited space I like the thought of an Blaze King Ashford 20. But will it suffer from the same tendency to overdraft given the higher draft requirements on the Hearthstone than the Blaze Kings?

Thanks for reading this novel and any input is greatly appreciated!

 

[EatenByLimestone]

Can you put a new bypass gasket in? I bet forcing all of the air through the cat would slow the burn down.

 

[Egbert Souse']

Can you put a new bypass gasket in? I bet forcing all of the air through the cat would slow the burn down.

I attempted it. Hearthstone must use a proprietary gasket. They said it was 3/8" but after installing it i could see light thru the door. Too thick.

 

[stoveliker]

Any stove will not be happy with too much draft, though some stoves need more draft to function well than others.

(BTW, is your cat not clogging with fly ash? That's what happens often with too high draft.)

Can you partially close (magnets) some secondary air? I don't know the model of the stove, but you have the opportunity to do something there.
A BK would be hard to tame if key damper(s) don't work, and here you likely do have some way to tame the unregulated secondary air. I suspect, though, that this has already been mentioned in another thread of yours?

 

[Egbert Souse']

Any stove will not be happy with too much draft, though some stoves need more draft to function well than others.

(BTW, is your cat not clogging with fly ash? That's what happens often with too high draft.)

Can you partially close (magnets) some secondary air? I don't know the model of the stove, but you have the opportunity to do something there.
A BK would be hard to tame if key damper(s) don't work, and here you likely do have some way to tame the unregulated secondary air. I suspect, though, that this has already been mentioned in another thread of yours?

Good call. My cat needs cleaning every two weeks minimum or it'll be fully clogged. This is my first thread on the subject but I suppose I could try the magnet trick. The dampers work but it's the length and stability of burn I'm most interested in improving.

 

[stoveliker]

Ok.
I don't know how this stove is set up, but are you saying the primary air is thru (only) the dog house? (And not from a glass air wash slit above the door?)

You may need to block the dog house if you do have primary air over the window too (not sure how if that shares an incoming sir opening with the air wash), and then limit secondary air inlet. But others may have more insight for that in this stove.

Limiting secondary air is common. Search for magnet in the wood stove forum and you'll find many mentions of that. Possibly even with the same stove.

 

[Egbert Souse']

Ok.
I don't know how this stove is set up, but are you saying the primary air is thru (only) the dog house? (And not from a glass air wash slit above the door?)

You may need to block the dog house if you do have primary air over the window too (not sure how if that shares an incoming sir opening with the air wash), and then limit secondary air inlet. But others may have more insight for that in this stove.

Limiting secondary air is common. Search for magnet in the wood stove forum and you'll find many mentions of that. Possibly even with the same stove.

There is an air wash. I assume the sides of the dog house have channels that bring air up behind the sides of the door/door opening and over the glass. There is a single secondary fed by a riser in the center of the rear of the stove. I haven't even gotten so far as to look at where the air wash outlet is. I suppose that's my next project.

 

[DuaeGuttae]

I have a BK Sirocco 30 box with a very long chimney. I'm not quite sure how long, but it goes through two standard eight-foot stories, an attic space, and there is plenty braced outside to clear the roofline. I don't remember the exact length, but I believe it's more than twenty-five feet. We do not have a key damper and were worried about too much draft, but we have not had any problems controlling our stove. We have had some fly ash on the catalyst at times that we've brushed off, but it has never clogged, and we are able to turn the stove down for the expected low, long burn. We've never tried for a full thirty hour burn and our wood is not ideal at this point as we're burning a lot of somewhat punky-in-places poplar, cedar, and cherry, but I know that once we got a twenty-six hour burn without even really trying.

I can't speak to your current stove and how to improve that, but I can say that a BK stove can still burn well even on a long chimney. Mine doesn't have major offsets, but it does jog at the level of the first floor ceiling and at roof level so that might reduce things somewhat. I also live in Virginia, where it's not so cold all winter, but the stove handled single-digit temperatures just fine with no signs of overfiring or cat clogging.

I don't know if that helps you much, but I thought I'd give your our experience of a BK on a long chimney.

 

[Egbert Souse']

I have a BK Sirocco 30 box with a very long chimney. I'm not quite sure how long, but it goes through two standard eight-foot stories, an attic space, and there is plenty braced outside to clear the roofline. I don't remember the exact length, but I believe it's more than twenty-five feet. We do not have a key damper and were worried about too much draft, but we have not had any problems controlling our stove. We have had some fly ash on the catalyst at times that we've brushed off, but it has never clogged, and we are able to turn the stove down for the expected low, long burn. We've never tried for a full thirty hour burn and our wood is not ideal at this point as we're burning a lot of somewhat punky-in-places poplar, cedar, and cherry, but I know that once we got a twenty-six hour burn without even really trying.

I can't speak to your current stove and how to improve that, but I can say that a BK stove can still burn well even on a long chimney. Mine doesn't have major offsets, but it does jog at the level of the first floor ceiling and at roof level so that might reduce things somewhat. I also live in Virginia, where it's not so cold all winter, but the stove handled single-digit temperatures just fine with no signs of overfiring or cat clogging.

I don't know if that helps you much, but I thought I'd give your our experience of a BK on a long chimney.

This helps tremendously. My guess is that the gasketed catalyst and the thermostatic air control are enough to attenuate the draft from the front end rather than the chimney end. Thank you!

 

[stoveliker]

I have a BK on a 27 ft flue, though with two 90s and a long horizontal section.amd that deceased draft considerably.

While one can not argue with observations like DuaeGuttae, in general I would not solve a flue problem with a new stove.
It's not guaranteed to work, and it's an expensive solution.

Also, if you do go this way, the BK comes with a metal cat that has smaller holes than a ceramic cat. It'll clog sooner than a ceramic cat. I don't know what you have now?
Note that the air inlet does have a minimum (a hole) that is unregulated.

 

[Egbert Souse']

I have a BK on a 27 ft flue, though with two 90s and a long horizontal section.amd that deceased draft considerably.

While one can not argue with observations like DuaeGuttae, in general I would not solve a flue problem with a new stove.
It's not guaranteed to work, and it's an expensive solution.

Also, if you do go this way, the BK comes with a metal cat that has smaller holes than a ceramic cat. It'll clog sooner than a ceramic cat. I don't know what you have now?
Note that the air inlet does have a minimum (a hole) that is unregulated.

Typically I'd agree with you with regard to replacing stove for draft issue. In this instance I'm intending to solve a length of burn issue and a draft problem that seem to be connected. If there's a single solution to two problems I'll take that option. If not, I'll get creative and see what I can solve with some magnets or an inlet damper on my outside air kit.

My cats now are metal. Despite running the stove pretty hard they don't look warped or anything. They just clog up easily.

 

[EatenByLimestone]

I attempted it. Hearthstone must use a proprietary gasket. They said it was 3/8" but after installing it i could see light thru the door. Too thick.

It’s worth trying an OEM gasket.

 

[EatenByLimestone]

Typically I'd agree with you with regard to replacing stove for draft issue. In this instance I'm intending to solve a length of burn issue and a draft problem that seem to be connected. If there's a single solution to two problems I'll take that option. If not, I'll get creative and see what I can solve with some magnets or an inlet damper on my outside air kit.

My cats now are metal. Despite running the stove pretty hard they don't look warped or anything. They just clog up easily.

They can be related. Draft sucks air into the stove. It burns the wood faster. It also doesn’t sound like you’re loading the stove up completely in order to avoid overfiring it. Loading the stove up more would increase burn times.

Hearthstone says on low you should be able to get 16 hours out of a load. I’d think real world you should be able to get 8.

 

[Egbert Souse']

They can be related. Draft sucks air into the stove. It burns the wood faster. It also doesn’t sound like you’re loading the stove up completely in order to avoid overfiring it. Loading the stove up more would increase burn times.

Hearthstone says on low you should be able to get 16 hours out of a load. I’d think real world you should be able to get 8.

I often load the stove completely. This requires both dampers fully closed to prevent overfire and I'll have coals remaining after 5-6 hrs only if I use very dense wood and pack the stove full and choke it down almost immediately. These types of burns are a delicate balancing act of loading the stove tightly, manipulating the air control and adjusting the dampers which typically takes nearly an hour. This is another practice I'd like to avoid as my wife is unwilling to go through all this when I'm not home for fear of the stove running away. The thought of loading the stove and not worrying about it is a nice one. Though it may be a bit of a pipe dream with my stove and chimney setup.

 

[stovelark]

The bypass door gasket I would suspect is the area of your concern and issue, of course it should be in place. If not, then the hot air above the fire will take the least resistive path out (through the totally not sealed bypass door). Does the air control have a controlling effect? You have a good amount of chimney at 25 feet, but not excessively. I'd think two dampers would really clamp it down for airflow... I'm wondering if the stove is pulling in air from somewhere it shouldn't be. I'd address the bypass gasket first. From your description it seems airflow is not being kept in control, ideally and normally, you should be able to fully load and still control the burn rate with the air control. If your chimney is drafting that hard, I'd think any stove will give you the same results. It sounds pretty impressive that that little stove (small/medium) is heating that area, espec with the cold we've had this winter. Good luck.