Thanks very much Waulie.. That is definitely a new spec. I see that Tom has added a listing for Durock Next Gen. Good for you and Tom catching that. I am guessing that the addition of perlite is what raised the insulative value.
woodstock progress hybrid epa numbers/clearances
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As a typical engineer myself, I'm sure they have some pretty significant factors of safety in the hearth requirements. Basically, I'm 99.9% sure my hearth would be OK. I would never take the chance, but it is a little frustrating knowing that you could probably take the required R-value and divide by 2 or 2.5 to get the actually number at which the subfloor could burn.
Just to be clear, I am absolutely not recommending anything less than what the manufacturer requires!
If it came down to it, I wonder if folks with existing hearths will be able to figure out what they have exactly?
Going by Tom's table, concrete is only R = .095/inch. I am not following how you got ~.3. if there is 1/4" tile on 1.5" of concrete. Did I miss something?
The new spec is because this is a new product. The old style Durock or Wonderboard is no longer on the market.
The new spec is because this is a new product. The old style Durock or Wonderboard is no longer on the market.
Yeah, he does list concrete as 0.095 per inch. He also lists cement mortar as 0.1 per 1/2 inch. That's twice as much! Oly technical difference between cement mortar and concrete that I am aware of is mortar has no large aggregate. It kind of makes sense, though, as large aggregate would transmit the heat much faster.
Waulie said:
I stand corrected so that means my hearth is .78 R-value, 2- 1/2" layers of Durock Nexgen plus tile.. I only needed ember protection so I am in good shape..
Ray
Abolutely! It appears the NexGen is even better than the original Durock now.. Glad that's been straightened out..
Ray
Ray
BeGreen said:
BeGreen, I think you may be correct about measuring from the glass. I always erred on the conservative side, and when my inspector measured he used the absolute leading edge of the FV. If your stove has an ash lip, you would be penalized by it. I will speak w/ WS about this important detail, but it would be nice to see it in writing.
fire_man said:
Hi Tony,
My inspector measured from the ashlip too and said this stove barely fit and he was wrong! In reality I have ~19" if measuring from the front door which is what the manufacturer says to do.. I am comfortable that this hearth is fine.. He also said I didn't have enough rear clearance but my chimney is directly behind the stove which protrudes 3' from the combustible wall.. You can point this out during inspection, I wasn't home during the inspection but he passed it anyways.. whew!! The chimney stone behind the stove barely gets over 100 degrees and the floor stays cool however my cats have a surface temp of 140 degrees lol! They may ignite and run through the house burning it to the ground lol..
Ray
At least the delays make a bit more sense now--not only the gov't and labs taking their time, but also WS tweaking and re-testing. Still curious if generating such an "enormous amount of heat" (so as to require additional shielding, etc.) will have an effect on burn times at the lower end and/or running away at the top end. Will be fascinating to find out from people's in-home experiments.
Norumbega said:
I am concerned about this, too. All I can say is WS claims "Burn time up to 16" hrs" and they are usually conservative in their claims.
raybonz said:
Ray: Was that inspector out to lunch? How could it not have enough rear clearance when it was a masonry structure behind the stove? If front clearance is really measured from the glass, I wish the stove installation sheet was specific, otherwise its subject to inspector interpretation, and to cover themselves, they will take the safe path. Can't blame them.
I don't see why having high output at the top end with the secondary burn would affect the low burn with the cat. I think I read that the Progress' glass is *not* IR reflective. Maybe this gives the larger front clearance. . .
fire_man said:
I hear that Tony! If he would went down cellar he would have seen the cinder block going up into the 1st floor but that's OK he passed it and the ins. co. has the paperwork..
Ray
raybonz said:
This always should be in the stove's documentation under the hearth requirements. Then there is no ambiguity. Be sure to ask Woodstock to supply written documentation if it is not in the Progress Hybrid manual.
I was just told that they are looking at a different glass to reduce the front clearance.
I was also told they are currently looking at 18 inches as measured from the front edge of the stove, not the glass.
I was also told to not count on that R-value being reduced from 0.59, but it is still "possible".
I asked about rear clearances, but the answer was confusing. I gather with the stove pipe shield it was 6 inches from stove pipe to combustables. Not sure exactly if that is the limiting factor or not.
Some numbers should be on their blog soon.
BeGreen said:
I agree BG however that is what went down while I was at work.. At least he passed it so it's a non-issue.. I'd rather he err on the side of caution but if we know the facts we can always dispute the untruths fortunately he was smart enough to know it was safe.. I am glad I did everything by the book for our safety and peace of mind..
Ray
OOps I read that post too quickly, you were referring to the Progress.. Funny thing is he read the specs from my stove manual which were required to be present for the inspection..
Waulie said:
Kind of surprised they are still looking into glass solutions this late into the game.
BeGreen said:
LOL I think he was blind in one eye and couldn't see with the other.. He had the same info that you posted and I went above and beyond the minimums..
Ray
Den said:
Right, that's what I sort of tell myself too. But then I wonder about the existence of secondary air interferring with damped-down low burns, and then how exactly "the Progress will automatically deliver unused secondary air to the combustor at lower burn rates" (from blog). I guess as you close the primary air (for a low burn), the other wing of the butterfly damper closes the secondary air too, sending it off to the cat? Is there a channel in there for just that purpose? And can you really get rid of all the secondary air? Anyway, mainly just wondering if the hybrid design is all gain and NO compromises. Will be fun to see!
Den said:
I agree with this comment. I personally saw the air plate that controls intake air. The primary air plate (located in the rear of the stove) shuts completely closed with no air allowed. A small air slot in the bottom front of the stove allows a small controlled amount of primary air to always enter the burn chamber to eliminate backpuffing. The seconday air plate (attached to the primary plate ) does have slots in it that always allows some air intake. The claim is this stove can burn down to a low of 10K BTU/Hr.
fire_man said:
Ok, thanks, that's easier to visualize. Is that 10k figure the official EPA result? I thought I read a speculation of 5k, from someone talking to someone at the open house.
Norumbega said:
At the open house I was verbally told by WS the FV low end burn was 5K, the Progress low end burn was 10K. I am not sure if these were EPA #'s or WS #'s. Until we see them posted on their site I would not count on them being official.
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