does radiant heat work under carpet in basement?

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I am thinking about using radiant heat panels (Roth) in an in process finished basement. I have hydronic already in the house with a boiler. But I would be using carpet in the basement...will these types of radiant heat setups work well in a basement with carpeting?
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snipped-for-privacy@yahoo.com wrote:

I'm thinking that radiant heat *can't* be good for carpet or its backing.
--
Notan

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Notan wrote:

Your thinking is incorrect.
Matt
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A heated floor becomes uncomfortable to walk or stand on when its surface temperature exceeds 85 degrees F, which means a few degrees higher than that under the carpet. Do you really suppose that 88 deg F will be harmful?
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Is there any insulation underneath the slab and, if so, how much? Carpet and under pad are reasonably good insulators and so more of this heat will be re-directed downward and out of your home. It doesn't strike me as a good idea, especially if the slab is uninsulated.
Cheers, Paul
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Paul M. Eldridge wrote:

Yes, the slab should be insulated from the ground no matter what floor covering is selected.
Matt
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Doug Miller wrote:

I thought it might affect different carpets/backings, differently, but according to Matt, I'm wrong.
I guess Matt knows!
(I'd still check with a carpet person, first.)
--
Notan

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Radiant heat is used under carpet frequently. It's just not a problem. 88 degrees won't hurt the carpet. (Would you worry about the carpet being harmed by high temperatures in the summer, if you didn't have air conditioning?)
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Doug Miller wrote:

I wasn't thinking short term effects, but rather, long(er) term.
Apparently, I was wrong!
--
Notan

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Notan wrote:

I researched hydronic radiant heat before building my log house. It certainly is a good idea to do your own research though, and it isn't a good idea to post incorrect information.
Matt
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I am not sure that the foundation was insulated underneath...is there a way to verify? The house was built in 2000 and I don't know the builder. The original owner wouldn't know either. Is there a way to check/verify (without digging under the foundation of course).
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snipped-for-privacy@yahoo.com wrote:

Stand on it barefoot for ten minutes. If it feels pleasantly cool, it's probably insulated. If it feels cold, it's probably not.
Or you could try measuring the temperature of the slab with an IR thermometer. I'd expect it to be noticeably above 60 deg F if it's insulated, but that's just a guess.
--
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Doug Miller (alphageek at milmac dot com)
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Doug Miller wrote:

That is funny. It would take a pretty well calibrated set of feet to tell the difference in ten minutes for a standard 4" thick slab.

This won't work either as there are too many uncontrolled variables. You are looking for a rate of heat transfer, not an absolute temperature. Depending on the ambience temps in the basement, a slab could be at 60 F whether it is insulated or uninsulated. If you knew of a slab nearby that was insulated and one that wasn't, you might be able to heat a spot on both and watch the cool down rate with an IR camera and compare them to your slab. But that is a lot more work than finding the original building or drilling a 1/2" hole and seeing if you hit foam. A core bore would give you a more accurate sample, but a simple drilled hole would tell you if foam was there, but it would be harder to get the exact thickness.
Matt
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I just realized that there is an open 1ftx1ft hole in the floor for the roughed in shower drain. There is crushed stone in the bottom . I can probably scoop some of it out looking for insulation. How far down is the foam board insulation usually in a foundation? If there is none, should I not conisder radiant floors there? A friend of mine said he had routed out plywood to run pex tubing and that was it for his radiant floor...he hasn't hooked it up yet and it was on his second floor. Is that an option for a basement floor (need to lay plywood).
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On 12 Mar 2007 12:58:56 -0700, snipped-for-privacy@yahoo.com wrote:

The insulation, if it exists, should be directly underneath the concrete slab. And would I use radiant heat without insulation? Sorry, I'm not *that* rich!
Cheers, Paul
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snipped-for-privacy@yahoo.com wrote:

It should immediately under the concrete and above the gravel. If you have to dig through much gravel to find it, then it probably isn't there.
Running the pex within plywood or furring strips covered by plywood is your only option. It is probably still worth it, but certainly won't be as effective as it would be with an insulated slab. If you have enough head room you could always lay insulation on top of the slab and then lay the pex on top of that and over with plywood. However, you are now adding close to 3" to your floor which may be an issue.
Matt
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Just verified that there is no insulation. Would laying 3/4" of foam on top of slab (R4 I think), then plywood with pex be a good approach? Do I need the aluminum in the plywood to make it work? It seems it would be cheaper to route my own plywood and snap the pex in. My other option is to use hydronic baseboard heaters...
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snipped-for-privacy@yahoo.com wrote:

It would probably work, but I would contact one of the many makers of this equipment and get their advice. They have worked with a lot of different situations and know their systems best. If you are at the design stage, it is time to get help from the folks that know best.
Matt
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Radiant floor heat works by "radiating" the heat into the living space. The more surface area, the better. When the tubing is placed within the concrete, the entire slab becomes the radiator. Otherwise, you'll most likely need the aluminum plates to take the heat from the PEX and radiate it into the room. I doubt you would get enough heat from the bare tubes to be efficient.
If you insist on hydronic floor heat, there are companies that make panels with the aluminum plates and tubing channels ready to go. One source is:
http://www.warmzone.com/hydronic-radiant-floor-heatin.asp

If you really want radiant, you might want to consider electric radiant. Very low profile, and easy to add as a retrofit. The warmzone site above also offers some of those too.
Of course, the simplest option would be to add in-wall electric heaters like those made by Cadet or King Electric. We heat our entire house using King Electrics "Pic-A-Watt" heaters. They're quiet, efficient, and we can zone each room for only the heat we need.
Anthony
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snipped-for-privacy@yahoo.com wrote:

There may be, but I'm not aware of any way other than core boring the slab in a non conspicuous location. Locating the builder would be the easiest way. It seems the municipality should have building permit records that might tell who the builder was.
Matt
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