Skip the block off plate and stuff Roxul directly on fire box of insert?

cnice_37 · Sep 30, 2011

I've searched and while there are extensive posts on block off plates I can't find the answer I am looking for.

My plans before burning season were to install a block of plate to prevent heat loss in my Jotul Rockland insert. The chimney is external brick.

I took off the surround yesterday to check some dimensions. It got me thinking...

Above the firebox is the air channel the blower forces the hot air out of. From cast iron top of firebox there is a maybe 1.5" x width of the box channel formed by some sheet metal on 3 sides. I'd basically be leveraging the sheet metal that is in place there.

What are the cons of insulating directly on the top of the insert? I'm not sure of potential hazards or lack of effectiveness so please educate me. Essentially I would eliminate the sheet metal shelf most block of plates are made of, and rather than insulating on top of that insulate directly on top of the sheet metal on the insert itself.

There is a cap on the top of the chimney and so it is blocked off up there (albeit not insulated.)

The pros for me are obvious : no sheet metal needed, don't need to remove the insert to install, less time, less $$.

Cons?

Thanks for any help.

mellow · Sep 30, 2011

I would use kaowool for this if you do try it, I would get a thicker 1" blanket of it and put it all around the back of the insert like a hot water heater jacket.

Only downsides I have come up with is your insert might run hotter and you will have to keep an eye on it till you see the difference. The only thing keeping me for trying it is finding a deal on 1" kaowool.

If you have some cash here is what you need: http://www.ebay.com/itm/Ceramic-Fib...765?pt=LH_DefaultDomain_0&hash=item19c8d8c4d5

begreen · Sep 30, 2011

Have you asked your dealer or Jotul about this? A similar question was asked about the Clydesdale a week ago. The reply was don't do it. There is a risk of overheating the stove. If your idea fails, are you ok with damaging the stove? Seems like an expensive experiment to me. Put in an insulated block off plate and there is no risk.

bpm44 · Sep 30, 2011

I'll add that I recall reading that years ago, before EPA stoves, people were putting their Fisher Stoves tight to concrete block walls, or cuttings legs down and stuffing them in the fireplace openings and such. As a result, during cool down when fires would go out the stove bodies were cooling at different rates from front to back and it was actually causing them to crack due to the heat retention of the surrounding materials. Now those were some bullet proof thickly walled stoves too!

Obviously those folks were violating the three foot clearances that were spec for them. I'm not saying this would definitely happen to you EPA stove with it's air jacket, but it is food for thought. I don't know of any stoves that are tested for an insulation blanket to be so close.

I'm going to have to vote for doing it the hard way and pulling the stove out, putting in a proper plate with the insulation above it and not having to second guess yourself. IMHO no stove is inexpensive if you have to replace it - not even the great deals on Englanders.

burntime · Oct 1, 2011

I stuffed Kaowool on top and then the block off plate. It makes a huge difference. An extra 20 minutes will make leaps and bounds difference in efficiency and safety. Remember, you are sleeping 20-50 feet from a 900 degree firebox...

BrotherBart · Oct 1, 2011

All of the insulation on the planet still doesn't solve the problem of heat loss up in the chimney walls. If you don't want to install the plate, just stuff Roxul up in the first flue tile to block the heat loss.

But as I said in another post, wear a mask. That is nasty short fiber stuff and you will get as much in your lungs as you do in the chimney.

cnice_37 · Oct 1, 2011

All good feedback, thanks.

I have read on the subject and numerous times the mask recommendation comes up, so that is definitely in my plans.

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Skip the block off plate and stuff Roxul directly on fire box of insert?

cnice_37

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mellow

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begreen

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bpm44

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burntime

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BrotherBart

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cnice_37

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