Woodstock Keystone, clearance and code question for superinsulated home

[Pig Bodine]

Hello!

I'm just now getting interested in wood burning after having used wood heat about 15 years ago. Obviously things have changed and I've been getting up to speed on the new stove advancements since then. This forum is a great resource!

We have a superinsulated, airtight home and the design heat load limits us to low output stoves. I'd much prefer a longer burn time and this basically leaves the cat stoves with Blaze King and Woodstock being the two leading options. Because the main living area area where the stove will be placed is small, the Woodstock Keystone is the best fit from a footprint standpoint. However, if anyone has other stove suggestions I'm happy to hear them.

There is a quirk in the Keystone install manual regarding the dimensions of the wall shield. The clearance off the back to combustibles is 14.5" with a stove shield and 12" with a wall shield. I'd like the option of a 12" clearance, again because the stove is going in a small space. The problem with the wall shield size has brought up before in this thread, although this is for Progress install: https://www.hearth.com/talk/threads/options-requirements-for-wall-shield.89780/

Basically it states that the minimum wall shield width is 81" and 56" tall. The height is not a problem but a nearly 7 foot wide shield for low BTU stove seems wrong. I've been in contact with Woodstock and they state that this is based on the 36" rule for clearance. NFPA 211 uses 36" to combustibles as a default for non-tested stoves, although this one is clearly tested for tighter clearances. Woodstock also told me combining a stove and wall shield will not reduce the size of the wall shield.

Here's how I think the shield size can be reduced. The 81" is for a 1" air gap. NFPA 211 appears to measure the 36" on a line from the stove corner, touching the edge of the shield and then to the wall. I've attached the figure straight from the 2016 code book. If I want to reduce the width of the wall shield I could just increase the air gap bringing the shield closer to the stove, or increase the thickness of the shield which would have the same effect. This would leave the shielded area of wall the same with smaller shield footprint, correct? Let me know what you think.

 

[bholler]

Hello!

I'm just now getting interested in wood burning after having used wood heat about 15 years ago. Obviously things have changed and I've been getting up to speed on the new stove advancements since then. This forum is a great resource!

We have a superinsulated, airtight home and the design heat load limits us to low output stoves. I'd much prefer a longer burn time and this basically leaves the cat stoves with Blaze King and Woodstock being the two leading options. Because the main living area area where the stove will be placed is small, the Woodstock Keystone is the best fit from a footprint standpoint. However, if anyone has other stove suggestions I'm happy to hear them.

There is a quirk in the Keystone install manual regarding the dimensions of the wall shield. The clearance off the back to combustibles is 14.5" with a stove shield and 12" with a wall shield. I'd like the option of a 12" clearance, again because the stove is going in a small space. The problem with the wall shield size has brought up before in this thread, although this is for Progress install: https://www.hearth.com/talk/threads/options-requirements-for-wall-shield.89780/

Basically it states that the minimum wall shield width is 81" and 56" tall. The height is not a problem but a nearly 7 foot wide shield for low BTU stove seems wrong. I've been in contact with Woodstock and they state that this is based on the 36" rule for clearance. NFPA 211 uses 36" to combustibles as a default for non-tested stoves, although this one is clearly tested for tighter clearances. Woodstock also told me combining a stove and wall shield will not reduce the size of the wall shield.

Here's how I think the shield size can be reduced. The 81" is for a 1" air gap. NFPA 211 appears to measure the 36" on a line from the stove corner, touching the edge of the shield and then to the wall. I've attached the figure straight from the 2016 code book. If I want to reduce the width of the wall shield I could just increase the air gap bringing the shield closer to the stove, or increase the thickness of the shield which would have the same effect. This would leave the shielded area of wall the same with smaller shield footprint, correct? Let me know what you think.

View attachment 230057

You need to go by whatever Woodstock says. They tested it they know what is needed.

 

[Pig Bodine]

Doing whatever Woodstock says is the goal. The point is that I don't think they tested that wall shield configuration, so this becomes question regarding the code, not this particular stove. That clearance is straight out of the NFPA 211 code book as a default minimum for untested stoves. I could personally design a stove with the same dimensions, make sure it's UL listed but do no clearance testing and come up with that exact same measurement. Why would they pay for clearance testing only to use the default?

I'm more interested generally in what people think about reducing the wall shield dimensions per NFPA 211 by moving the shield closer to the stove by increasing the air gap or shield thickness? The 1" gap to combustibles is a minimum and the shield has to be 1" away from the stove. That leaves 10" of room to work with, realistically 5" with the air control on the back of the Keystone. The shield border could be moved anywhere along the diagonal lines from the stove corner in the image I posted with resultant reduction in the wall shield dimensions, correct? The effective shielded area of wall is the same.

 

[AlbergSteve]

"Footprint" is not just the size of the stove, but includes all the clearances required - I would look at the Blazeking 20/30 series stoves which have 6.5/6'' rear clearances. You may find that the stove might be larger(deeper), but sits much closer to the wall than the WS.

 

[Highbeam]

Good choice on making long burn times a priority. You can also burn the hot and fast if you want. A wide range of available outputs is very important.

I too would be happy with a Woodstock or a bk. I would have bought a Woodstock last time but the rear clearance requirements were huge! So I chose a bk instead.

All of these shenanigans to gain 2.5” ? Just use a stove shield and be right with the manual. Stove installation requirements are not the place to cut corners.

 

[Pig Bodine]

Thanks for the help!

It's definitely true that total stove footprint would be nearly the same between the 20 series BK and the Keystone but for two issues. The extension of the hearth into the room is much less with the Woodstock because it's a side loader and the hearth extension off the front is reduced further if you elevate the hearth, as low as 2 inches per the manual. The wife also likes the look of Woodstock although the Ashford would be good too if it didn't have the steel components off the back.

I'm absolutely not trying to cut corners. I should have titled this thread differently as this is really a code question, one that would be relevant to many other installs, and something I'm just generally curious about. I received a PM agreeing that my code interpretation was correct that used the analogy of the stove as a light source and the shielded area of the wall as a shadow, which is exactly how I'm thinking about it. A smaller shield can create the same "shadow" as a larger shield if the smaller shield is closer to the stove. Just wanted to get folks opinion on that.

If I do go with the Woodstock I'm using a stove shield whether or not there's a wall shield. Seems like cheap insurance. Right now there's a low clearance freestanding gas unit in front of drywall. We're building a hearth anyway for aesthetic reasons so why not gain a couple inches of setback distance if we can?

 

[bholler]

Thanks for the help!

It's definitely true that total stove footprint would be nearly the same between the 20 series BK and the Keystone but for two issues. The extension of the hearth into the room is much less with the Woodstock because it's a side loader and the hearth extension off the front is reduced further if you elevate the hearth, as low as 2 inches per the manual. The wife also likes the look of Woodstock although the Ashford would be good too if it didn't have the steel components off the back.

I'm absolutely not trying to cut corners. I should have titled this thread differently as this is really a code question, one that would be relevant to many other installs, and something I'm just generally curious about. I received a PM agreeing that my code interpretation was correct that used the analogy of the stove as a light source and the shielded area of the wall as a shadow, which is exactly how I'm thinking about it. A smaller shield can create the same "shadow" as a larger shield if the smaller shield is closer to the stove. Just wanted to get folks opinion on that.

If I do go with the Woodstock I'm using a stove shield whether or not there's a wall shield. Seems like cheap insurance. Right now there's a low clearance freestanding gas unit in front of drywall. We're building a hearth anyway for aesthetic reasons so why not gain a couple inches of setback distance if we can?

Yes your interpretation of the code is absolutly correct. The problem is because your stove is ul listed the only thing that matters is what Woodstocks manual says. It overrides any code. If they say you need a sheild that large that is what you need. I agree doing what you said makes sense and should be perfectly safe. But you need to do what the manual says

 

[Pig Bodine]

The thing is that the manual is vague. It states that the wall shield should cover "36" beyond the stove". When I emailed Woodstock they said the shield needed to cover anywhere that could be touched by a yardstick from the edge of the stove. The wall shield dimensions in the manual figure are noted to be an example, which I assume is with a 1" air gap although that is not explicitly stated, and they specifically note that dimensions vary with distance between the stove and wall. The dimensions don't seem like an absolute requirement which is why I have the code question. I think they put this in the manual to help people interpret the code when they put the stoves in. Probably because most Woodstocks seem to be owner installs as they don't have the dealer network.

 

[bholler]

The thing is that the manual is vague. It states that the wall shield should cover "36" beyond the stove". When I emailed Woodstock they said the shield needed to cover anywhere that could be touched by a yardstick from the edge of the stove. The wall shield dimensions in the manual figure are noted to be an example, which I assume is with a 1" air gap although that is not explicitly stated, and they specifically note that dimensions vary with distance between the stove and wall. The dimensions don't seem like an absolute requirement which is why I have the code question. I think they put this in the manual to help people interpret the code when they put the stoves in. Probably because most Woodstocks seem to be owner installs as they don't have the dealer network.

I agree the manual is not great. But it does say it must cover 36" beyond the stove. And there are lots of woodstocks installed by pros we install a few every year. They just dont have dealers that do it.

 

[Highbeam]

If I was your building inspector I would require 36” beyond the stove per the manual which is more than 7’. Unless That yard stick from the corners thing is on the manual.

Haven’t seen a yard stick in a long time.

 

[bholler]

If I was your building inspector I would require 36” beyond the stove per the manual which is more than 7’. Unless That yard stick from the corners thing is on the manual.

Haven’t seen a yard stick in a long time.

Our bank just had a stack of them sitting out for free. I took one just because i hadnt seen one in a long time.

 

[Pig Bodine]

Hah, agree, not sure we have a yardstick. The "36" beyond the stove" is clearly not flat wall distance based on their example of an 81" shield width from the manual figure immediately below the paragraph. That would mean an 81-36-36 = 9" stovetop which is about 15 inches short. They also include the clearance table for rear clearance direct from the NFPA 211 code right below that. That's why I emailed them and they told me about the yardstick measurement from the corners. The yardstick statement is identical to the figure from my first post which is a screenshot from the code book.

I'm sure there's plenty of pro Woodstock installs which we may do ourselves but I would guess there's more owner installs then average just given their business model. I also think it's why they have this whole section in the manual instead of just saying "install per NFPA 211 when using a wall shield" or something to that effect.

 

[BCC_Burner]

Here's your code interpretation from a Building Inspector: I would not sign off on the install unless the wall shielding was installed to meet or exceed the requirements stated in the manufacturer's stove manual. End of discussion.

I would certainly be polite and friendly about it, I actually really enjoy homeowner projects, as it is an opportunity to educate and inform people, and part of that would be giving you a call before coming out to ask that all documentation is available on site for me prior to inspection (stove manual, spec sheets on stove pipe and Class A, etc.).

 

[bholler]

Here's your code interpretation from a Building Inspector: I would not sign off on the install unless the wall shielding was installed to meet or exceed the requirements stated in the manufacturer's stove manual. End of discussion. No stove manual on site = no inspection.

That is how it should be. Unfortunately many inspectors dont even look at the manual.