No need for a subfloor, but he IS right about the self leveling compound. The mats can go right over the concrete, and then self leveling compound to bury the mats and give him a flat surface to tile. Far as I'm concerned, it's actually easier than over woodframe.

Thanks Bill Is there one brand over another that you prefer or that you know works well??

any thermal break is better than none. Without it, you are heating the whole slab along with your tiles. The heating cables are designed to warm up the tile fast if they are not also called upon to heat a slab at the same time.

We used Nu-Heat mats. Our tile guy likes working with their mats (fabric-like, rather than plastic mesh) and DH was very impressed with the assistance he received when he called the company with our pre and post purchase questions. They'd gotten rave reviews here on GW. They do cost a bit more than some of the other brands (you do have the option of using standard size mats, custom, or a combo of the two), but DH felt the added cost was worth it for this purchase.

Our Tile guy usually buries the mats in the mud, but the info DH got from Nu-Heat indicated that it should be laid over the mud, so that's what they did here. First the mud (cement?), when it was dry (within days), a thin layer of thinset, the mat, and then another thin layer of thinset. When they were ready to lay the tile, they use a normal of thinset for our tile.

Although some heat is lost into the slab, it's minimal, because of the fact that heat rises.

I hate to tell ya.

"What Bill said"

I have layed tons of heating wire over cold basement floors. You know the best thing that happens to them - they get warm?

The cables give of little heat and the cold slab will not suck the heat down.

I think last time I worked out the math - an average install of a 220 volt system uses about $65.00 per year in electricity - this is very efficent... And quite cost effective.

My thoughts.

JW

Warm toes rock....

All that said - I would love a good thermal Break?

Can I use Kerdi Board David? Green EBoard maybe? Regular foam? Would Kerdi not do it?

Good Question and good point David - what is the answer...

I think Electric heat is the most

anyone can make a mistake. The best tilesetter can too. The most valued tile forum advisor can too.

Heat only rises if it is warmer air (or fluid) surrounded by cooler air (or fluid).
And that is only a portion of the total heat transmitted.

The rest gets radiated in all directions.

Heat in a solid does not go in a direction opposite to gravity.
Heat in space does not go in a direction opposite to gravity.
Radiated heat is the means of heat transfer for most of the energy transferred in the universe.
When we say "heat rises" we are saying something shorthand for the convection current caused by air moving away from a heat source.

Let's be clear about this first.
If we cannot understand, all together, all of us, what I just wrote above, then we are not qualified to go to the next step in the logical process.
This is enough new information for this post.

Do you prefer mats or wires... and who is happy with their heated floors and what manufacturer. I would appreciate any info on this as I am purchasing this week... Thank you for all the information.
Everyone prefers one way or another, but Bill has helped me in the past with my kitchen remodel 2 years ago with so much valuable information I could never thank him enough!!!

mats have a lot of advantages compared to gluing loose wire.

all manufacturers of electric heating cable are making the technical equivalent of a toaster or a hair dryer. It's resistance in wires that makes heat. Consumer Reports will tell you that converting electricity into heat by using resistance in wires is so old-tech that there is no difference in any manufacturer's products. Hope this helps you move on to other topics. How about the features in the thermostat?

bill has been helping a lot of people by constantly posting answers, and he deserves recognition for this.

hth

Haven't used our Nu-Heat consistantly, but have had it on a bit with some of the cooler days/nights we've had in NY the past few weeks. I like it!

The mats are supposed to be easier for installation. One of the reason our tile guy (and DH) prefers the Nu-Heat Mat, is that the wires are embedded in a fabric (like) material. I guess it's easier to lay out than some of the other materials (e.g. plastic mesh) used, and might be easier to position on the floor(?).

FWIW, we used the Solo Thermostat (from Nu-heat as well). I don't remember why, but DH liked that one best, vs the other two offered.

Thank you cat mom. I checked all the local electrical stores and tile places in our area (NE Pa.) they all carry the same ones Easy Heat. I called 7 of them!!! Did you order yours directly from NU Heat or an online supplier?

We ordered ours directly from Nu-Heat. They took the order directly, but then the actual sale had to be processed through a retailer (local?).

bill has been helping a lot of people by constantly posting answers, and he deserves recognition for this.

But nobody's right all the time, and Like I said the other day-- if I'm wrong, I expect (and hope) to get called on it. Good call.

Perfect thermal isolation is an idealization; there is always some "thermal contact".
The study of heat conduction between solids is thermal contact conductance (or thermal contact resistance).
Thermal contact does not imply direct physical contact.

--

http://en.wikipedia.org/wiki/Heat_conduction
++
http://en.wikipedia.org/wiki/Thermal_radiation
= TWO factors that combine.

Heat moves in a solid touching other solid matter.
Slab to Tile.
Tile to Slab.

--

Not
http://en.wikipedia.org/wiki/Convection

--

The more general case :

http://en.wikipedia.org/wiki/Thermal_contact
http://en.wikipedia.org/wiki/Heat
http://en.wikipedia.org/wiki/Heat_transfer

http://en.wikipedia.org/wiki/Thermodynamics

--

The whole subject can be studied from the opposite point of view.

http://en.wikipedia.org/wiki/Thermal_insulation
http://en.wikipedia.org/wiki/Radiant_barrier
http://en.wikipedia.org/wiki/Multi-layer_insulation
http://en.wikipedia.org/wiki/Building_insulation
http://en.wikipedia.org/wiki/Building_insulation_materials

Placing heat cables on a slab, under tile, means that you are heating the slab and the tile. More about this later.

Heat, like electricity, does take the path of least resistance. The top of the tile is closer than the bottom of the slab, so the majority of the heat produced by mat heads in that direction where it is transferred to air. When the air is as warm as the tile, the heat won't be able to transfer into the air and will spread through the slab in a different direction.

David I love the links!

Thanks for the nice neat reference.

What would you personally recommend for my home? Can I send you a picture of my slab prep? The floor is a little rough because we had to bust in and redo all the waste lines.

It's getting cold - I would like to work out the savings of this Thermal

I decided to go with Nu-Heat mats and ordered yesterday. They said I will have by Tuesday. Our contractor wants to put the subfloor so I guess that is what we will do. Thank you to everyone for all the information. Thank you cat mom for letting me know you are happy with your NuHeat. I cant wait as our bathroom and laundry room tile was always so cold before, hopefully this will be nice and warm on our feet.

You are welcome! Like I said, we haven't turned ours on in the MB all that often yet (DH hasn't flipped the circuit yet on the one in the hall bath), but I've been enjoying it on the nights/mornings I have had it on!

I wished we had put it in the guest bathroom downstairs (we're also in a bi-level). We used that bathroom exclusively when both upstairs baths were demo'd, from sometime in March, until mid-late June, when the MB finally was functional. That floor in the downstairs bath was quite chilly!

Hope you enjoy it!