PE Increased clearances How Much Closer 1" Air Space

[MattFoley772]

I'm very familiar with this table, used to refer to it all the time back in the days when we sold unlisted stoves. Note that although lines (a) and (b) allow a maximum clearance reduction of 33% and 50% respectively, the next column limits the actual clearance minimum to 24" and 18". This table doesn't apply to UL listed stoves, which have specific clearance requirements determined by the test lab: you can't apply a clearance reduction to a UL listed stove by shielding the wall, unless the manufacturer has tested with that technique and specifically allows for it in the installation manual. Nor can you apply NFPA shielding techniques (a) and (b) to locate any stove any closer than 24" and 18", respectively.

SO... the OP cannot use the existing shielding to reduce the Summit's 7-1/2" rear clearance requirement, even if he ventilates it. However, there would be an advantage to drilling the air holes: by ventilating the airspace, he gets to measure from the original wall instead of the surface of the stone.

Hi, I recently installed the UL-listed Isle Royale in corner installation. Manual mentions only one way to reduce clearance: use double wall pipe. (see attached, E and F dimensions) This reduces clearances of the pipe and stove by 16" (22" to 6"). This stove gets very hot (as other Isle Royale owners attest) so it makes no sense to me how double wall pipe allows the stove to be 16" closer--does the double wall pipe magically make the stove below it cooler? Please explain, I have searched for days for an answer.

Also, please tell me why "you can't apply a clearance reduction to a UL listed stove." Why can't I install wall protection and reduce clearance that way? I know I can install wall protection anyway per NFPA211, but why doesn't the manual allow it? What possible harm could come from putting up wall shields and moving stove closer?

 

[MattFoley772]

Hi, I recently installed the UL-listed Isle Royale in corner installation. Manual mentions only one way to reduce clearance: use double wall pipe. (see attached, E and F dimensions) This reduces clearances of the pipe and stove by 16" (22" to 6"). This stove gets very hot (as other Isle Royale owners attest) so it makes no sense to me how double wall pipe allows the stove to be 16" closer--does the double wall pipe magically make the stove below it cooler? Please explain, I have searched for days for an answer.

Also, please tell me why "you can't apply a clearance reduction to a UL listed stove." Why can't I install wall protection and reduce clearance that way? I know I can install wall protection anyway per NFPA211, but why doesn't the manual allow it? What possible harm could come from putting up wall shields and moving stove closer?

Related:

https://www.hearth.com/talk/posts/1599778/

 

[Mark Richards]

In my Drolet Escape manual the stove could be installed with 5" corner clearance using double wall pipe. In the manual it said that these clearances could be further reduced by 66% using sheet metal spaced 1" from the wall, etc....
I installed it this way with corner clearance of 2.5" from the wall and I can tell you that the wall behind the sheet metal is cool to the touch even when burning 24/7. You must make sure that stove pipe is the required 6" from any vertical combustable and 9" from the ceiling (US) though. Having said this, I would say if the manual for your stove doesn't state the same as mine, I would follow the manufacturers recomendations.

 

[thechimneysweep]

Also, please tell me why "you can't apply a clearance reduction to a UL listed stove." Why can't I install wall protection and reduce clearance that way? I know I can install wall protection anyway per NFPA211, but why doesn't the manual allow it? What possible harm could come from putting up wall shields and moving stove closer?

Presumably, you don't have a test lab at your disposal to ensure that your shielding allows the clearance reduction you're looking for. You're only allowed to further reduce listed clearances by shielding if the stove was tested with that shielding and found to be safe. Whenever that's the case, that shielding technique will be specifically allowed in the owner's manual.

This stove gets very hot (as other Isle Royale owners attest) so it makes no sense to me how double wall pipe allows the stove to be 16" closer--does the double wall pipe magically make the stove below it cooler? Please explain, I have searched for days for an answer.

Essentially, what the test lab is saying is that the stove is safe at 6" clearance, but at that placement the pipe is too hot. So, they'll only allow you to place the stove at 6" clearance if you use shielded pipe.

 

[MattFoley772]

That may be what the lab is saying but I don't believe it, not after feeling my walls.

I will grant that pipe and stove clearances are safe, from the corner out to the E dimension. The rear heat shield does a good job protecting that area, the walls are cool to the touch.

I do not grant that the stove clearance is safe out from the E dimension. The rear heat shield offers no protection forward of it. The walls get almost painfully hot to my hand now, so obviously they will only get hotter, plus the area of extreme heat will expand out, up and down the walls when the stove is closer with double wall pipe. Yet everyone here is basically telling me to disregard that and just trust the manual.

If someone could show me proof that walls are safe regardless of being painfully hot then I'll believe it. I keep reading about the benchmark "90 degrees above ambient temperature" but I've seen NO EVIDENCE substantiating this claim. Also, what does that actually mean? "Ambient" can mean many things. (Also, wooden handles on stove doors get way hotter than 90 degrees above ambient and no one seems to mind.) Allegedly all the labs test to this standard...but why? If there is evidence then WHERE IS IT? I've seen many opinions and appeals to authority but no evidence.

I thought I was getting close to an answer here but it went nowhere:

https://www.hearth.com/talk/threads/clearances-to-combustibles-theory.102329/page-3#post-1323135

I just did a search for "90 degrees above ambient" and found this.

(broken link removed to http://www.rumford.com/emissions/clearancetest.html)

Note the statement about "whether this test has anything to do with fire safety is an open question." You can say that again!

 

[thechimneysweep]

Here's a discussion on the subject you might find helpful: (broken link removed to http://www.chimneysweeponline.com/hohotwall.htm)

 

[MattFoley772]

Thank you, Tom. That makes me feel a little better.

Your website is very informative and helpful.

I still want to know why my Isle Royale manual does not allow me to reduce clearances with wall protection per NFPA211. Everyone is telling me the manual overrides NFPA211.

 

[begreen]

Doesn't the IR manual's ** footnote for dimension "I" in the dimensions table essentially describe a wall shield to NFPA211 specs?

 

[MattFoley772]

That is only for rear vent, mine is top vent.