Harman Owners: What Kind of Floor Protection?

Careful · Post by **Careful** » Mon. Jan. 12, 2009 12:23 pm

For any Harman Mark operators: What kind of floor protection are you using? The manual specifies a "non-asbestos stove mat with a K Factor of .84." but doesn't give a required thickness. My state (Mass.) requires 4 inches

off .84 K factor millboard in the absence of manufacturer listed requirements, so any help would be appriciated!

Post by **coaledsweat** » Mon. Jan. 12, 2009 12:51 pm

Just go down to the brickyard and get 4, 4"X6"X8" concrete blocks, about $2 a piece.

WNY · Post by **WNY** » Mon. Jan. 12, 2009 1:40 pm

Are you say 4" Clearance to combustibles? Normally some of the stoves have legs, that are at least 4" off the floor, then just put the mat down under it.

Careful · Post by **Careful** » Mon. Jan. 12, 2009 2:01 pm

Not 4" clearance. 4" of mill board. That sounds excessive to me. and mill board is not cheap stuff. I'm wondering if a regular stove pad would satisfy the inspector.

SuperBeetle · Post by **SuperBeetle** » Mon. Jan. 12, 2009 2:08 pm

I built a brick hearth for my Mark II. It can get pretty warm underneath. As far as the stove pad, I'm not sure about that.
Coal can "pop out" from time to time. I just had it happen today and have some nice burns on top of my feet

Careful · Post by **Careful** » Mon. Jan. 12, 2009 2:13 pm

So like 1 layer of brick? Was it OKed by a building inspector?

coalvet · Post by **coalvet** » Mon. Jan. 12, 2009 2:41 pm

I had an additional metal heat shield fabricated to fit under my stove inside the four stove legs, standing on its own legs, and the brick beneath this shield stays nice and cool. I don't know how high the legs are on your Harman but if there is room it's something to consider.

Rich

SuperBeetle · Post by **SuperBeetle** » Mon. Jan. 12, 2009 3:06 pm

Yes. 1 layer of brick. Inspected by my insurance company. At the time, PA building codes in my area were minimal but that has changed.

Cato · Post by **Cato** » Mon. Jan. 12, 2009 3:22 pm

I built this double brick hearth about 30 years ago. Use to have a wood stove on it then a Warm Morning Coal stove and now a Harman Magnafire Mark I. I'am 38 inches from the back wall (sheetrock) and a good 18 inches sides and front. Good luck and stay warm and safe!

Razzler · Post by **Razzler** » Mon. Jan. 12, 2009 5:05 pm

Careful, Don't forget that the Harman stoves have the ash pan area (most coal stove do) and you really don't get alot of heat under the stove. I can put my hand on the concrete floor at any time, even if I have the stove cooking at 700* I can hold it there as long as I want with no problem. I think that the minimum requirements are fine.

Careful · Post by **Careful** » Mon. Jan. 12, 2009 6:16 pm

Good point! Didn't think of that.

lowfog01 · Post by **lowfog01** » Mon. Jan. 12, 2009 6:24 pm

[quote="Careful"]For any Harman Mark operators: What kind of floor protection are you using?

I built a hearth for my Harman II out of bricks and concrete. I cut a piece of plywood the size of the hearth. I put that in the location the hearth was going to be and placed one row of brick around the edges; when that dried I filled it with cement. Then I capped that structure with a second layer of brick. The finished hearth is 5 inches thick. I put toe board around the floor/hearth joint for a finished look. I used matching brick as a façade on the rear wall heat shield; not the real brick but the thin slices. It was easy to do and didn’t cost an arm and a leg. It looks nice and made the inspector happy.

dad2hannah · Post by **dad2hannah** » Wed. Jan. 14, 2009 6:44 pm

WE did 4X4 blocks underneath it with concrete board under the blocks. We have the III

Careful · Post by **Careful** » Thu. Jan. 15, 2009 11:28 am

I spoke with my local Harman dealer and SHE said “As long as it has a K factor of .84 it’s good”. My building inspector said pretty much the same thing. He just wants to see a spec sheet that says K=.84 on it. So I guess I could buy a 1/16” thick sheet of millboard from McMaster Carr and according to these people it would work! I guess I have to look out for myself. My stove dealer also gave me a hard time when I asked if she could call Harman to check on the required thickness of K=.84 material! She said my building inspector was being unreasonable! (I was trying to get the information for myself, but I didn’t tell her that). I tried sending a Harman an email, but it didn’t go through, so I tried calling Harman direct. I’m sure you folks know where that went! I waited on hold for 30 minutes . . . . . . . . and then got disconnected, without ever talking to a real human. Tried calling again and just kept pushing 0 for the operator, but that went nowhere. It’s almost like that don’t want to deal with you after they have your money!
I also researched manufactured stove pads thinking I’d put one of those in (a different Harman dealer said they were often used). There was no K factor listed on the instruction sheet, so I called their customer service. Guy said their K factor is .914 or there abouts. I say Oh, so I guess this won’t work. He says, Sure! It’s bigger than you need! You’re good! I explained what the K factor was (using an example in an email HE sent me), and he says let me check that with my production manager and get back to you. Been two days now.
I’m just venting.

CapeCoaler · Post by **CapeCoaler** » Sat. Jan. 17, 2009 1:04 am

They should spec a thickness.

Technical Note: Conductivity
Cement backer board is an ideal material for a hearth pad because of its low “k”, or conductivity value. Conductivity is the ability to conduct heat. The lower the “K” factor, the less heat is conducted through the material. For example, Durock has a k-value of 1.92 per inch, as compared to the k-value of common brick, which is 5.00 per inch, or marble, which has a k-value of 15.00 to 20.00 per inch

From
**Broken Link(s) Removed**

If the appliance is to be installed on a combustible floor or a combustible floor covering, it must be installed on a 1” thick non-combustible millboard floor protector or a durable equivalent, with a “R” factor of no less than “2.” The pad must be installed beneath the unit, extending 16” (U.S.) on the side equipped with a door, and 8” on all other sides. The pad must cover any horizontal chimney connector runs and extend 2” beyond each side.
Alternate Floor Protection:
An easy means of determining if a proposed alternate floor protector meets requirements is to follow this procedure:
1) Convert specification to R-value:
i R-value is given – no conversion is needed
ii k-factor is given with a required thickness (T) in inches: R = 1/k x T
iii C-factor is given: R = 1/C
2) Determine the R-value of the proposed alternate floor protector:
i Use the correct formula given in step 1 (above) to convert values not expressed as “R.”
ii For multiple layers, add R-values of each layer to determine overall R-value.
3) If the overall R-value of the system is greater than the R-value of the specified floor protector, the alternate is acceptable.
EXAMPLE:
The specified floor protector should be ¾” thick material with a k-factor of 0.84. The proposed alternate is 4” brick with a C-factor of 1.25 over 1/8” mineral board with a k-factor of 0.29.
Step (a): Use formula above to convert specification to R-value. R = 1/k x T = 1/0.84 x .75 = 0.893
Step (b): Calculate R of proposed system.
4” brick of C = 1.25, therefore R brick = 1/C =1/1.25 = 0.80
1/8” mineral board of k = 0.29, therefore Rmin.bd. = 1/0.29 x 0.125 = 0.431
Total R = Rbrick + Rmineral board = 0.8 + 0.431 = 1.231
Step (c): Compare proposed system of R of 1.231 to specified R of 0.893. Since proposed system R is greater than required, the system is acceptable.

From http://hearth.com/econtent/index.php/forums/viewt ... ead/26491/

Harman Owners: What Kind of Floor Protection?

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