Is My Hearth Floor Too Hot??

[Rob From Wisconsin]

My current setup is ceramic tile over 1/2" cement board.
I've been keeping track of my temps directly underneath out stove,
and with a "blazing" fire that has been going for many hours, I've
read a floor temp that seems to peak around 140-150 degrees.
Is this OK for my current hearth materials??

Thanks....

 

[EatenByLimestone]

Seems overly hot to me. I don't think it should be any hotter than the walls and they are considered too hot if you don't want to leave your hand on it. What is under your cement board? Concrete slab or wood joists?



Matt

 

[Rob From Wisconsin]

Seems overly hot to me. I don't think it should be any hotter than the walls and they are considered too hot if you don't want to leave your hand on it. What is under your cement board? Concrete slab or wood joists?



Matt

2" x 6" studs I believe. Even so, it's not too hot too touch or hold your hand on that surface.
So, it can't be much more than a 140 degrees with that in mind.

 

[NH_Wood]

Same setup as me, although my cement board (hardi-backerboard) is on 3/4 plywood, which is raised on upright 2x4's, so the stove sits about 5" off the floor. Can you provide info on the rest of your pad construction? My pad gets warm to the touch, but I don't think it's nearing 150 degrees, but not sure - never measured. Cheers!

 

[Rob From Wisconsin]

Same setup as me, although my cement board (hardi-backerboard) is on 3/4 plywood, which is raised on upright 2x4's, so the stove sits about 5" off the floor. Can you provide info on the rest of your pad construction? My pad gets warm to the touch, but I don't think it's nearing 150 degrees, but not sure - never measured. Cheers!

I think my hearth is similar to yours. The problem I've got with mine is that the Tribute has really
short legs, and no ash tray, which means a lot more heat can get to the floor, a lot more than most
stoves. As a matter of fact, the manual recommends like an 1"+ of cement board, which is not my
current hearth. To help, I cut & inserted a piece of plate steel with 1/2 spacers & placed inside on the
floor of the firebox. It seems to help quite a bit, without creating an overflow of ash. I've heard it said
that if a surface temp is over 140 degrees, it will be almost impossible to hold your hand on that
surface. I don't have that kind of heat right now, so maybe there is no problem.

 

[Slow1]

Sounds to me like you have your summer project lined up - redo your hearth to bring it up to spec, then get rid of that stove modification. I would not be comfortable with that temperature unless I knew that the hearth was in compliance with the recommended specifications.

Long term running too hot can (will?) degrade the wood under that hearth and eventually you could be at a point of real danger. Given how long it takes chances are you will have long forgotten and it will catch you by surprise and happen at the worst possible time (i.e. middle of the night or when nobody is around or...). It simply isn't worth it in my opinion. Of course, it is MY opinion I'm giving and it is your home/stove/install. Best of luck whatever you decide.

 

[begreen]

140 °F is still a safe temp. However, if you can hold your hand on it for more than a couple seconds, the temp could be cooler. Slightly warm is like 110 deg. By 120 deg. it is starting to feel quite hot. By 130 deg you probably don't want to hold your hand on it for more than a second or two.

Note on wall temps, the wall is considered at a safe temp if the surface is less than 70°F over ambient. Though as a general note for comparison, hot water heating pipes with water at a steady 180 °F often run alongside of and through combustibles.

 

[Rob From Wisconsin]

140 °F is still a safe temp. However, if you can hold your hand on it for more than a couple seconds, the temp could be cooler. Slightly warm is like 110 deg. By 120 deg. it is starting to feel quite hot. By 130 deg you probably don't want to hold your hand on it for more than a second or two.

Note on wall temps, the wall is considered at a safe temp if the surface is less than 70°F over ambient. Though as a general note for comparison, hot water heating pipes with water at a steady 180 °F often run alongside of and through combustibles.

No, it is definitely nowhere near 180 °F to the touch. Anyways, doesn't the cement board act as an
insulator? In other words, if you measure 140 °F surface, it will be considerable less on the other
side of the cement board??

 

[gandrimp]

Run your hot water faucet til the water is good and hot .Then compare the feeling.
140 should be very uncomfortable.And most water heaters are in the 140 range.
I have found that a 100 degree shower is to hot,I know TMI but for comparison sake

 

[Rob From Wisconsin]

Run your hot water faucet til the water is good and hot .Then compare the feeling.
140 should be very uncomfortable.And most water heaters are in the 140 range.
I have found that a 100 degree shower is to hot,I know TMI but for comparison sake

Great idea!
I gave it a try, and my floor is nowhere near temp. of hot tap water.
I guessing my floor temp might get near to 130 degrees, at the high end.
Then again, it might not even be that hot.......

 

[Battenkiller]

Run your hot water faucet til the water is good and hot .Then compare the feeling. 140 should be very uncomfortable.

Not a good comparison at all. For reasons that I don't have time too get into, heat transfer from water is a lot more rapid and efficient than, for example, a hot piece of wood. I can easily hold my hand on a rough wooden surface that is 200º F, but I can't stand to leave it in my 135ºF (measured with a lab thermometer) tap water for more than a few seconds. The floor joists above my stove in the basement have hit almost 140º at times and I can grab hold of them as long as I want and they only feel warm, and you'd be surprised how hot the surface of a piece of wood can get when standing by your stove and still be comfortable to pick up and place in the stove. Best bet is to get a cheap IR gun and shoot the temp of anything that concerns you. $50 or less is cheap peace of mind IMO.

 

[NH_Wood]

Same setup as me, although my cement board (hardi-backerboard) is on 3/4 plywood, which is raised on upright 2x4's, so the stove sits about 5" off the floor. Can you provide info on the rest of your pad construction? My pad gets warm to the touch, but I don't think it's nearing 150 degrees, but not sure - never measured. Cheers!

I think my hearth is similar to yours. The problem I've got with mine is that the Tribute has really
short legs, and no ash tray, which means a lot more heat can get to the floor, a lot more than most
stoves. As a matter of fact, the manual recommends like an 1"+ of cement board, which is not my
current hearth. To help, I cut & inserted a piece of plate steel with 1/2 spacers & placed inside on the
floor of the firebox. It seems to help quite a bit, without creating an overflow of ash. I've heard it said
that if a surface temp is over 140 degrees, it will be almost impossible to hold your hand on that
surface. I don't have that kind of heat right now, so maybe there is no problem.

Ah....no ash tray - that must be why your setup is warmer than mine. Not sure how your legs compare to mine though (stove legs that is......, although my legs are pretty darn nice). Perhaps place a thermometer on the pad and see what you get - good luck! Cheers!

 

[begreen]

Why is the stove being run with an under spec hearth? We are just speculating about the temperature. This is not a good way to install or run a stove. It must be built to the manufacturer's minimum design spec.

 

[firefighterjake]

Why is the stove being run with an under spec hearth? We are just speculating about the temperature. This is not a good way to install or run a stove. It must be built to the manufacturer's minimum design spec.

This was my thinking exactly . . . my own feeling is that when it comes to safety of myself, my family and home I will always be sure to meet and even exceed the manufacturer's specifications well before firing the stove up . . . even for a small test fire.

 

[Slow1]

Why is the stove being run with an under spec hearth? We are just speculating about the temperature. This is not a good way to install or run a stove. It must be built to the manufacturer's minimum design spec.

This was my thinking exactly . . . my own feeling is that when it comes to safety of myself, my family and home I will always be sure to meet and even exceed the manufacturer's specifications well before firing the stove up . . . even for a small test fire.

Ditto - I just re-read my post and I suppose I wasn't very clear on this point. Seems rather self evident to me that the hearth should be brought up to spec - problem solved, no further need to worry.

 

[Battenkiller]

I just re-read my post and I suppose I wasn't very clear on this point. Seems rather self evident to me that the hearth should be brought up to spec - problem solved, no further need to worry.

No, you were perfectly clear. That's why I didn't mention it. :cheese: :red:

 

[begreen]

You were clear, but the focus started to drift. It was time to get back to the crux of the matter.

 

[Wood Heat Stoves]

tribute requires r value of 0.6
1/2" of cement board = approx 0.2r
the tile somewhere between .01 and .1r

checking floor temps is a good idea with an under built hearth....