Anybody installed the radiant floor heat in their

I poured the floor in my shop this past year, and I figured I might as well go ahead and run tubing for radiant heat, so it's there if and when I decide to heat the building. I found that the insulation required for a heated floor is a greater expense and aggravation than the tubing.

First, there's a lot of information on the web about radiant heat. Google on "radiant heat", "hot water radiant heat", "heated floor", etc.

First, for the insulation I used 25 psi compressive strength polystyrene insulation. It ran about $22 a sheet for 2" and about $12 a sheet for 1". I used 2" on the edges and for the first 4 feet from the wall. For the rest I used 1". This is a post frame building; for insulation around the edge, I ripped 2" insulation into 12" wide strips with a table saw, then ripped those strips in half with the blade set at 45 degrees. I glued the insulation strips to the inside of my skirt boards so that the sharp edge of the insulation was lined up with the top of the skirt board. (That way the concrete tapers out along the edge to minimize heat loss.) Under the slab, I laid down 4 mil plastic as vapor barrier and put the insulation on top of that. I'm not convinced that the vapor barrier is needed.

In order to insulate under the overhead door, I framed a skirt board where I expect the door to close (a couple of inches inside the door posts). This board is insulated like the other skirt boards. (If I had ran this skirt board outside the posts, several inches of the heated floor would be outside the building.)

For the tubing, I simply put down 6" wire mesh over the insulation and zip-tied the tubing to the mesh. You need about 1 foot of tubing for every square foot of floor area, which works out to a one foot spacing. I used 1/2" oxygen barrier PEX tubing, which runs about 40 cents a foot. Each loop should be no longer than 300 feet.

It will save you a lot of time if you sit down with a pad of graph paper and experiment with how you're going to lay down the tubing.

It's much easier to put down the PEX tubing if you have a helper, but I did much of it by myself.

I ordered my PEX tubing from MV Supply (see link). They gave me excellent service; I highly recommend them.

When you pour your slab, be aware that the insulation may affect how fast the concrete sets up. I poured the first half of my slab on a hot day in July; the concrete set up very fast. The second half was poured on a wet day in November; I wasn't sure the concrete would EVER set up. I suspect the insulation kept the heat in for the first pour, but prevented excess water from escaping during the second pour.

Good luck. I think it's well worth the expense and effort to put in radiant floor heat, but I've yet to hook mine up.

• Mountain View Supply

On the other hand, if you will only heat this building when you are using it i would stay away from in floor heat. in this case a better choice would be forced air, radiators, or a radiant heater. This is because in floor heat takes a long time to get the job done. It will have to run for a long time (4+ hours) to warm the concrete before the building will start to warm.

As far as a barn, a former member of one of the tractor boards put a system in his barn in upstate NY. Two downsides-cost to heat using a water heater on propane--he eventually converted to wood stove/boiler and secondly, he fell asleep while working under a truck on the warm floor.

That being said, radiant is a nice system. A word of caution, consult local and state building codes. In Michigan, the State just came down with a ruling that it was unacceptable to use a water heater as a source of heat for space heating in place of a boiler. Long explanation, but basically they said they would not accept it. If that is the case, a boiler is more expensive and may figure into the overall cost of the project.

FWIW,

JU

You need to install some insulation under the slab, how much is dependant on how you will use the system. Once the insulation is in place you install your rebar like you normally would, then run your pipe, using zip-ties to attach it to the rebar. I didn't do it, but I would recommend using a piece of conduit or building a box to protect the pipes where they emerge from the floor.

The two websites I found most helpful in doing my project were:

www.radiantec.com
www.durapex.com

Get the free quote from radiantec for a good idea of what you'll need for materials.

• Heating links

Floor heat does not like the boiler water as hot as baseboard or forced air systems do, and boilers do not like return water that is a lot colder than the return water from a conventional system, as it is with floor heat. Usually, some type of tempering valve is used, which corrects both problems by mixing hot boiler water with the cold return water. However, I have seen systems work OK without such a setup.

Some people put down styrofoam sheets, lay the loops of pipe, and cover with several inches of sand, and then the concrete.

I have seen installations where the plastic pipe is tied to the rebar, and imbedded in the concrete, or sometimes the pipe is stepped down into the concrete before finishing. I may be helpful to weight the pipe down by filling it with water, so it is not as apt to "float" towards the surface of the concrete.

I think it is important to have another source of heat, such as baseboard, or hanging fan-forced heater(s), which can be feed from the same boiler.
On mild days, it is nice to be able to take the chill off without building up a lot of heat in the floor, which will make the building uncomfortable later in the day, when outside temperatures come up, and the floor is warm. Also, the other heat sources come in handy for fast heat recovery on a cold day, if the door(s) have to be open for a length of time for ventilation, or moving equipment or vehicles in and out of the building.

I would also do a search on Google for in-floor heating. I'm sure you'd turn up a lot of info there.

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