Wood stove: temp of surrounding walls
How hot can the walls surrounding a wood stove get before it becomes a problem? (combustable, painted drywall, cellulose insulated wall)
The Napoleon stove I’ve been using is much closer to the walls than I’m accustomed to. Installed at an angle in the corner. double-wall chimney pipe. The last two winters the house was gutted and the heat tended to migrate. The studs behind the stove never got warm. Now I’ve got insulation and drywall on the walls and drywall on the ceilings.
I fired the stove up yesterday for the first time of the season. Good, dry wood that had been in the garage all year. With the stove up to temp, the wall above-behind the stove felt hot. Not so hot that I couldn’t keep my hand on it, but hot nevertheless. I just wanted to be sure that it wasn’t going to be an issue.
jt8
The creative individual has the capacity to free himself from the web of social pressures in which the rest of us are caught. He is capable of questioning the assumptions that the rest of us accept. — John Gardner
Edited 11/10/2008 11:04 am by JohnT8
Replies
All units differ so you're doing the right thing looking at the instructions. You should be OK if you've followed the instructions. The surrounding walls are certainly going to get warm to the touch. I'd monitor it a little and see if it gets too warm to touch.
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Most of our wood stove commentators must be on the recently banned list. Wood stove threads usually have a little more activity.
The surrounding walls are certainly going to get warm to the touch. I'd monitor it a little and see if it gets too warm to touch.
I figure a bit of paranoia can save a lot of problems later. Whether that means buckling the recently painted wall surface or burning the house down.
So would your gut reaction be that it isn't a problem as long as the wall isn't too hot to touch?
jt8
The creative individual has the capacity to free himself from the web of social pressures in which the rest of us are caught. He is capable of questioning the assumptions that the rest of us accept. -- John Gardner
If you've got it installed per manufacturer's instructions, I'd feel the wall on occasion. If you can keep your hand there, I wouldn't worry about it.http://www.quittintime.com/ View Image
"general rule of thumb is that if you can keep your hand there, you are OK."
seeyou and piffin are agreeing on this point, so it must be gospel. We get junkhound and Doud saying the same thing and we'd have the whole choir singing the same song (pretty rare on BT).
jt8
The creative individual has the capacity to free himself from the web of social pressures in which the rest of us are caught. He is capable of questioning the assumptions that the rest of us accept. -- John Gardner
I think that song has been banned.
The only function of economic forecasting is to make astrology look respectable. --John Kenneth Galbraith
The fl;ash point for dry lumbner is in the neighborhood of 450° or so normally.
But a condition occurs ( forget the name - carbonation or something) when wood fibres are repeatedly exposed to temps above 250° and the flash point gets lower and lower over the years.
250 is pretty darn hot though. general rule of thumb is that if you can keep your hand there, you are OK.
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Right. By continuously overheating the wood you can lower its point of combustion to under 200F -- that's the big hidden hazard of wood stoves -- a stove can operate fine for years and then "poof".But by scrupulously observing mfgr's instructions (including those about not overheating the stove) you should be safe from the hazard.Around these parts, probably 90% of house fires are due to two causes:
-- Improperly installed wood stoves.
-- Using a torch to thaw frozen pipes.
The only function of economic forecasting is to make astrology look respectable. --John Kenneth Galbraith
Hey Piffin,
Don't those clearances seam a bit tight?
I know you have quite a bit of experience with
stove set ups.
I don't think I've ever installed one that allowed it
to be that tight.
Not Piffin, but the clearances do seem tight. A single wall vent on a wood burning appliance usually has to be 18" from combustibles. The appliance tag seems a little confusing as it mentions a different set of clearances for the stove depending on the type of vent installed. The type of vent installed has (I am going to insert a correction for this post) some bearing on the stove clearances themselves. (A double wall uninsulated vent will allow a 6" clearance to combustibles from the vent piping only). Perhaps this appliance is not actually UL listed or CSA certified and therefore actually needs 48" all round and 60" above. An unlisted appliance (Unlisted is the key word here) that is shielded can reduce the side front and rear clearances by 12" to 36". A listed appliance can follow the manufactures guidlines.
Edited 11/11/2008 8:24 pm ET by losh
The type of vent installed has absolutely no bearing on the stove clearances themselves.
Yes it does in some cases. From the clearances listed on this stove, it's a reduced clearance stove meaning it has a jacket of some sort and it probably has a rear vent. If all that is correct, then the vent is the hot spot and is ruling the clearances. If the double wall pipe is used, then the whole unit can be moved closer to combustibles.http://www.quittintime.com/ View Image
You are correct, it would; I was thinking of the wall thimble clearances. ThanksEdited 11/10/2008 10:35 pm ET by losh
Edited 11/10/2008 10:43 pm ET by losh
"The type of vent installed has absolutely no bearing on the stove clearances themselves. "Generally true in principle, but not absolute. It depends on the relationship of where the flue is located on the stove re the outside edges of the box."Perhaps this appliance is not actually UL listed or CSA certified and therefore actually needs 48" all round and 60" above. "Typical install for anything not specifically designed and tested for closer clearances is 36" to combustible walls and surfaces, not 48"
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Quite true about the vent, l lost focus on the question; but NFPA and CSA standards call for 48" and 60" for unlisted appliances from combustible surfaces. 36" is allowed for an unlisted appliance only when the wall is shielded. (29 Gauge steel with 1" air space between the steel and drywall is an example of a shielded wall). Of course jurisdictional rules will apply in all cases, and the manufactures recommendations can be followed for a UL listed or CSA approved appliance.
can you link to a copy on that? I have NEVER seen or heard a claim of 48"
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Those codes can't be looked at online. You have to buy them (CAN/CSA B365-01) and NFPA 211. The heating level 2 course I took compiled their information from these references. The course is the Carson Dunlop Heating Level II module. If you do find a link to access the codes please let me know. Later
I have NEVER seen or heard a claim of 48"
They must have changed it since our woodstove retail days. It was 36" and losh is correct, you have to buy an NFPA 211. There's no online info except where to buy it and how much. I'm gonna have to take his word for it. http://www.quittintime.com/ View Image
Remember that the course I took compiled their info from those regulations and that the individual jurisdictions in fact can and do sometimes differ from these standards. Nova Scotia allows 3' for a Fuel oil supply tank to a burner. The rest of the world is normally 10' and may be 5' in some locations. Go figure.
Consider me on the update wagon.
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I'm not gonna challenge his word. I want to know when it changed and why.This shows it was still 36" in 2003 with NFPA
http://www.hearth.com/content/images/uploads/nfpachart2.jpgand here is a darn good article on installations that also has comments directly pertaining to John's Original Q.
http://hearth.com/econtent/index.php/articles/wood_stove_clearances_installing_it_safelyThe old standard was that a heat shield would by you a 50% reduction in clearance setback, but the charts are now showing a 67% reduction at sides, so it could be that what the Lord giveth, the Lord taketh away. Lessee, start with 36" and reduce 50% and you get 18"
start with 48" and reduce it 67% and you end up 15-3/4" so that moves the stove closer by the new standards once you add the heat shield.
http://www.woodheat.org/safety/safeinstallation.htmInteresting....Most manuf sites and insurance lists I see 36" still standard.The only direct quote I came across from NFPA said 48" to ceiling, but I have no way of verifying that this was the latest.A lot of articles like this one
http://www.hearth.com/econtent/index.php/articles/stove_wall_clear
speak of 36" for listed appliances, and some reckon that stoves older than 20 YO ( Gee, I had my stove business over 25 years ago) are likely to be unlisted. They must just assume age and lack of certification to make them somewhat less safe and thus add that extra 12" to make it 48" just for the unlisted stoves is all I can figure out.Since I am unlisted, you'll just have to sit 12" further away from me when we eat dinner together next time. Meanwhile, I can tell my wife that My age makes me hotter.Think she's believe it?;)
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I sold my store about 23 years ago and every unit I sold was UL listed. 36" was the clearance on non-jacketed radiant stoves. Adding shields changed the clearance at different rates on different models. I never encountered a situation where the 48" ceiling clearance came into play.http://www.quittintime.com/ View Image
I got to thinking after I posted that, I wonder where somebody writing that got the idea to recommend that units older than 20 were likely unlisted, because I know that every one I sold had either UL or ICBO listing, most of them both.came across another site that was from an AHJ in PA stating 36" again, but noting that home made and unlisted stoves would not be permitted.
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This shows it was still 36" in 2003 with NFPA
http://www.hearth.com/content/images/uploads/nfpachart2.jpgIf you look at your ref jpg from http://www.hearth.com (NFPA 2003), it is showing 36" with shielded wall (1" air gap between combustible wall and non combustible shield (I.E 29 gauge steel), so even that link is current.
Wall Protection
A basic rule which applies at all wall protection is that the least expensive and best insulator is air. This is the reason that most wall protection needs to be installed spaced away from the combustible wall which it protects.
Wall Protection for Unlisted Stoves
As mentioned earlier in this document, most unlisted stoves should be installed 36†from combustible walls. This clearance can be reduced to as little as 12†with the proper wall protection. There are a number of standards relating to such wall protection, so be sure to ask your building official or stove/fireplace pro which are used in your area. One very popular standard is published by the NFPA - National Fire Protection Association (http://www.nfpa.org). This standard is known as NPFA 211, and contains a wealth of information on stove clearances. A sample clearance reduction guide and diagram are presented here as examples: Clearance Reduction Table Diagram of Sample Installation
An Example of clearance reduction from this code states that a piece of 24 gauge sheet metal installed on spacers 1†from an existing wall will reduce stove clearances by 66% - or from 36†to 12â€. The clearance reduction is usually measured from the rear of the stove to the original combustible wall, not to the sheet metal.
Wall Protection for Newer Listed Stoves
Luckily for the newer stove buyer, most manufacturers have come to understand space limitations in modern homes. The result is that many - if not most - newer stoves are permitted to be placed much closer than 36†to combustible wall surfaces. Some models have additional heat shields that can be purchased which will allow even closer installation. Since each stove is different, you should consult the manual on your specific model. It would be wise to do this research BEFORE your purchase of a stove so that you can be assured your stove will fit your room and hearth design.
Ceiling Protection
Be careful when installing stoves in areas with low overhead clearance, such as basements and rooms with sloped ceilings. NFPA requires 48†from the top of a stove to a combustible ceiling. This can be reduced by use of proper protection. Some newer stoves call for less clearance - we’ve seen models which allow 3 feet and even less. As always, consult the manual for newer and listed stoves.
Alcove Protection
Older and unlisted stoves should not be installed in an alcove constructed of combustible materials. However, some newer stoves allow this installation and have tested their models specifically for this type of setup. This is another situation where it pays to do your research BEFORE selecting a stove model.
Pipe Protection
Stovepipe, also known as chimney connector, has to be a certain distance from both combustible walls and ceilings. One NFPA example calls for an 18†clearance to walls for 6†diameter stovepipe. This can be reduced by either: 1. Protecting the wall or ceiling adjacent to the pipe. 2. Installing an approve ‘Pipe Heat Shield†onto the stovepipe (reduces 18†to 9") 3. Using special interior double wall stove piping, which can reduce the distance to as little as 6â€. This pipe is usually manufactured by the same companies which produce Class A double wall chimney (Metalbestos, Excel, Duravent, etc.).
Once again, your stove manual, label or local professional is the best source of the exact specifications for your particular stove model.
http://www.quittintime.com/ View Image
Edited 11/12/2008 4:57 am ET by seeyou
Not to argue it further, but hopefully to put a cap on it, this is looking like one of those we put down to regional differences. The BIs and AHJs in some places are more carefull or the fire is hotter in some places
;)
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Sorry guys but you have to interpret the link you are sending properly. I am sticking with the 48" for an unlisted appliance to combustible walls. Quoted from the link you gave me "Clearance to combustible wall with PROTECTION as specified in table 9.5.1.2 or table 12.6.2.1." is 36". Thats a PROTECTED COMBUSTIBLE wall only. They are starting that distance with a protected wall. The table specifies the types of shielding of which all specify an air space behind steel or brick. Without this protection you need 48" for an unlisted appliance; end of story.The diagram also shows a min of 36 inches from the corner of the appliance to the edge of the protective shielding. Perhaps people are getting confused with this.
What is a "protected" wall? I'm not being argumentative, just trying to learn.http://www.quittintime.com/ View Image
A protected wall is one described in the tables that you referenced. All of them separate a combustible surface with an air gap and noncombustible material. The non combustible material cannot touch the combustible wall therefore an air gap with spacers is used to separate them. Brick or steel are usually used. Contrary to popular belief Concrete board (Durock) is not acceptable when attached directly to drywall. It must have an air gap and spacers, just like steel or brick. Hope this helps.
heat shielded. One of those charts gave a good half dozen different materials that could be used and the % of clearance reduction for each - most at 66%
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I was 16 when I installed a Franklin stove in my trailer. I used hat channel and I think asbestos board almost floor to cieling behind it, I went no more than 14" as I recall. The gap at the hearth floor ( brick, on floor, slate on brick) let air chimney up behind the asbestos..Oh, I covered the asbestos with stick on brick..Z-brick.
It got pretty warm to touch, bu never a real issue.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
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BRING BACK SPLINTY.
I am sticking with the 48" for an unlisted appliance to combustible walls.
OK, I buy that. But I was never speaking of unlisted units. The NFPA 211 standard for a listed radiant stove would still be 36" to combustibles. IIRC, there was not a separate standard for unlisted units 25 years ago. A UL listing was necessary for insurance purposes for it to be retailed. http://www.quittintime.com/ View Image
Absolutely concur with you.
I never even looked at the exact install clearances. It is what the manufacturer says so my opinion is of no bearing. I know that a lot of the newer stoves are designed for close clearances using the heat shield designs.
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I don't think I've ever installed one that allowed it to be that tight.
Me neither. But this one has vented steel shielding on the sides, back, and over most of the top.
Just can't seem to get a good shot of the sticker on the back.
jt8
The creative individual has the capacity to free himself from the web of social pressures in which the rest of us are caught. He is capable of questioning the assumptions that the rest of us accept. -- John Gardner
Pyrolosis?
I have a fairly recent Pacific Vista, installed as tight to the specs as possible....in fact, I had to cut a bay in the stud wall and tile that to get the needed clearance (and so I didn't need to move the chimney.....looks pretty cool). Anyway, even with a good fire booming out, my walls behind the stove don't get hot. Slightly warm is the most I've seen. Square to the wall, not diagonal.Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.
JohnTate
If you are really concerned then add a ventilated heat shield at the walls adjacent to to the wood stove
A metal or non-co.mbustable material set 1-2" from the drywall on non-combustable supports with a 2" gap at floor level and at ceiling level for convection ventilation.
And I would agree that the numbers presented for the manufacturer's clearance specs seem "too close", but I am not familiar with that stove.
.............Iron Helix
I have a LARGE wood burner in my garage. Mostly masonry surrounding it, but it is very close to my 4" pvc waste line, close enough to melt it, at the very least soften the plastic. I placed a couple of pcs. of Durock 3x5 in front of the affected area, not super attractive, but it's not going to burn either. Take them away after the heating season.
I've got that exact stove, installed exactly as you have, in a corner. Yes, the radiant heat will heat up surrounding areas, but not to the point of concern. I installed it as per mfg. specs, 12" to combustibles if I recall.
It's a great stove IMO, no complaints at all.
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.â€
I've got that exact stove, installed exactly as you have, in a corner. Yes, the radiant heat will heat up surrounding areas, but not to the point of concern. I installed it as per mfg. specs, 12" to combustibles if I recall.
Got a pic of how you've got it installed? I'm thinking of going to the local lumberyard and ordering a piece of 3/4" granite counter they sell and having them cut it in half. Slide the two pieces together and set the stove on that. Would give me around 50"x 42". I still need to take the measurements and see if that would give me the proper coverage.
Currently it is just sitting on one of those $30 pads you get at Menards.jt8
The creative individual has the capacity to free himself from the web of social pressures in which the rest of us are caught. He is capable of questioning the assumptions that the rest of us accept. -- John Gardner
>>>Got a pic of how you've got it installed?
Here are a few from a few years ago.
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Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.â€
Edited 11/12/2008 1:46 pm by Scott
Edited 11/12/2008 1:47 pm by Scott
Edited 11/12/2008 1:47 pm by Scott
Edited 11/12/2008 1:48 pm by Scott
Nice setup. That looks like a neat room. South facing? I'm surprised the dog isn't laying closer to the fire. You've got the door upgrade...the shiney brass. I ended up getting the black door and took the shiney brass off the front shelf. not because I didn't like it, but because it seemed easier to sweep ash off the shelf without the brass trim. I'll probably put it back on if I list the house.
I don't have the windows, but I have a doorway to the hallway in about the same position as your door to the left of the stove.
Did you make the hearth pad, or buy it? Don't think I've seen that shape before. Most pre-made 'corner' ones I've seen are big squares with a corner clipped off.
jt8
The creative individual has the capacity to free himself from the web of social pressures in which the rest of us are caught. He is capable of questioning the assumptions that the rest of us accept. -- John Gardner
>>>South facing? Yes, so on sunny winter days the stove isn't needed much.>>>You've got the door upgrade...the shiney brass.Gold plated. It was an accidental 'freebie' that the factory did by mistake. Normally it adds a cost.>>>I ended up getting the black door and took the shiney brass off the front shelf. not because I didn't like it, but because it seemed easier to sweep ash off the shelf without the brass trim. I'll probably put it back on if I list the house.You're right about that. Ashes always get caught around the trim and it has discolored over the years.>>>Did you make the hearth pad, or buy it? Don't think I've seen that shape before.What you see is temporary... the floor is still just painted ply! The tile is el-cheapo Home Depot stuff with black grout.I'm just finishing my latest project with this stove... adding an updraft ceiling fan to stir up the air. The hot air gets trapped in the rafters and just sits there. I'm very interested to see if the fan improves distribution. We bought a plain black commercial fan that should go nicely with the stove.Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.â€
Hey John - My stove store was in a old converted victorian home. There was an original fireplace in each room and we used them as burning diplays. The original tile hearths weren't large enough for the proper coverage for stoves, so I got 4x8 sheets of wonderboard and cut them down to the size I needed, covered them with tile and made wood trim to band the edges. They looked great and were pretty inexpensive. In fact, I sold several of them on custom order.http://www.quittintime.com/ View Image
I got 4x8 sheets of wonderboard and cut them down to the size I needed
It comes in 4x8?! Guess I haven't looked hard enough. Seems like most of the cementboard is like 3x4 or 3x5 or so. Did you use 1/2"?
Once the tile sets, does it make a solid enough unit that it can be picked up and transported without it buckling or such?
My initial thought was to build the hearth into the floor and run the finish flooring up to it. But as I lean more towards listing the house when complete instead of moving in... I tend to think that I want a setup that can be removed if necessary. If the buyer doesn't want the stove, I'd be more than happy to take it with me. So a hearth that can be easily removed is a plus. I've got an appliance cart and furniture dollies, so weight isn't THAt much of an issue.
cut them down to the size I needed, covered them with tile and made wood trim to band the edges
That is similar to some of the pre-made ones I've seen. Some have wood trim edges, some have steel banding. They tend to be somewhat pricey though. 99 cent/sq ft porcelin tile ones can be $100+. Lowes had some marble on clearance about a month ago that would have made a nice hearth. Or for more rustic, I like some slates.
The 3/4" granite I'm thinking about:
http://muranocollection.com/ColorsPrices.aspx
IIRC, the "counter" piece is 25.5x85" and starts around $150. Have the lumber yard cut it in half to make two pieces which can be scooted together to make a 51x42" hearth (assuming that gives me the coverage I need)
But then again, $150 would buy all the pieces I'd need to make a tile one.
And I've thought about running by the granite places and seeing if they had any 'remnants' that would work (and maybe get a rounded cut on it), but I'd like to keep the hearth height as low as possible. Regular counter granite would be 1.5", whereas the Murano stuff is only 3/4" and doing a tile setup could be about 3/4".jt8
The creative individual has the capacity to free himself from the web of social pressures in which the rest of us are caught. He is capable of questioning the assumptions that the rest of us accept. -- John Gardner
It comes in 4x8?!
Sorry. 3x8 & 3x5. The 3x5 was a little small. I was selling hearthstoves primarily, so the 3' width one way was adequate. Might not work for your stove.
Once the tile sets, does it make a solid enough unit that it can be picked up and transported without it buckling or such?
I never had any problem. We typically swapped the stoves out several times a year so we were rolling stove loaded moving dollies over them repeatedly. http://www.quittintime.com/ View Image