radiant floor heat

want to do radiant floor heat in my 40x60 pole barn,, have some questions about it ,,which insulation rigid foam or double bubble roll,, 1/2 inch or 3/4 pex,,12 inch spacing or more ,,boiler or tankless heater ,,and 4inch of concrete thanks cdv

Those questions are all answered after you do a heat loss calculation on the building. Suggest going to www.greenbuildingtalk.com for guidance. Otherwise all your getting is wags.
Jim B

Look online for SlantFin. There are some heat loss calculators that you can do yourself.

Never could stand hot feet, never could get away from it either. NOt for me.

The best website for advice is heatinghelp.com. Dan Holohan has written a book he sells on that site for the layman and radiant heat which is the most comfortable and least expensive heat to use. It's not cheap to install but in a pole barn, one must insulate under the floor with blue board insulation, especially around the perimeter of the building. Also, depending on the area one lives in dictates the choice of heat source. My brother built a pole building in Pinckney, MI and used a water heater. The building is used as a mechanical contractors shop and is kept at a comfortable 55F all winter.

I did my whole house including garage, I purchased everything from a company called Aqua-Therm, I think they are in Broten? Mn. Very helpful, had everything I needed, offered lots of free technical advise.

I have worked in shops that had radiant heat in the floor. Some use 1 or 2 water heaters, others use a small gas fired heat exchanger - miniature boiler. What I liked about it is that there is no cold spots anywhere.

You will want to run multiple liquid circuits in the floor. In case one would go bad you still have others that can heat.

The Case-IH Dealer in Mascoutah IL heats their entire shop with radiant floor heat, they have different zones and they say you can tell the difference when walking thru the shop. It's like walking into a different room. Like walking thru an invisible wall.

You want to go with 2 inch special high compression foam. Its spendy. Even better is going with two layers of 1 1/2 and alternating the joints. 1/2 pex, 12 to 16 inch spacing and your going to need a special in floor boiler for that large of building. Consider 5 or 6 inches of concrete if your going to have large equipment in the building. Also don't forget to insulate the edges of the concrete were it meets the outside wall.

Can I recommend that you take pictures of your pex layout before the pour, using tape measures or some kind of storyboard reference from the walls? They "May" come in handy someday, if you ever add a wall or attach something to the floor.

times two on that! i just hate floor heat, like walking on a stove all day. and with the heat on low also. i like my feet cool too.

Here"s a pic of just that- from 1997, when we built the new house. Cattle panel mesh, 6 x 4? inch pattern. Tied the pex to that.

Brooten, MN. Bought an Aqua-Therm wood boiler from them in "88. They"re the next town west of where I grew up. Good folks to deal with...two of my sons have their units as well.

I would do double bubble on the button for moisture protection plus reflective layer, then 2" construction grade foam over that.

Forget about the bubble wrap. Use real insulation.

It's most critical to insulate around the perimeter of your slab. 2" foam. Next most important thing is under the slab, and you want 40 psi rigid foam to support the concrete. Minimum 1 inch thick. As for the walls and ceiling, it should be obvious that the more insulation the better.

I did a fair amount of research into radiant floor heat several years ago when I poured my floor, so my PEX tubing is ready to be hooked up. I have yet to complete insulation of the shop, so the system isn't hooked up yet. You need about 1 linear foot of 1/2" tubing per square foot of floor, so you need to run at least 2000 ft of 1/2" PEX. Each loop should be no longer than 250 feet, so that means eight loops. You can run longer loops if you use 3/4", but it will be harder to work with. Spacing is dictated by how much tubing you have.

Note that you need to use "oxygen barrier" PEX for radiant heat systems. Regular PEX doesn't have an O2 barrier.

Figure out where you intend to cut your control joints, and protect the PEX there by shrouding it in those spots with larger tubing. Otherwise slab movement can sever the tubing.

A few years ago, everyone was using small water heaters for boilers. But these days very nice tankless units are available. They're pricey, but they take up very little space. Check out Menard's web site for some reasonably-priced tankless heater and control panels. The downside of tankless is it needs more Btus/hr than a conventional water heater, so you may need to run a bigger gas line to run a tankless boiler.