Radiant Floor heating within a ceiling/ floor.

Hey guys,

I am in the process of designing a TF Barn conversion, into a living space/ farm office. I am adding interior lofts within the two end bays/mows. I would like to heat the building with radiant floor heating, utilizing a OWB with a LP boiler backup. I want to divide the building into multiple zones. I can install the tubing under the first floor from the basement/ milking parlor, but I am looking to "sandwich" the tubing within the layers of the loft floors.

The sequence that I am concidering is as follows:

Top down:

3/4 in re-claimed maple flooring
3/4 in plywood subfloor
3/4 in x 6 in firring strips positioned over joists, with tubing running between strips
3/4 in T&G car-siding (pretty side down and seen from the first floor living space)
6 x 6 ceiling/floor joists


http://s453.photobucket.com/albums/qq254...s-section2D.jpg





Some ideas that I have been playing with are:

~Using 1/2 in tubing for flexiblity, making a single loop between floor joist spacing.

~Using thin reflective foil insulation under tubing to push heat up through floor.

~Using thin radiant tin plates to spread the heat to a larger surface under subfloor.

~Standardize tubing placement to allow for accurate nailing patterns for hardwood floor installation.


I am looking for anyone's advice, opinions, and encouragement .

Thanks! In advance!

Rooster

A friend of mine put radiant under his pine floors using lightweight concrete. He put t&g plywood over the floor joists, then used 1"x2" furring strips about 16" apart. After running the tubing, he used the furring strips as a screed and filled with what I believe is called gypcrete. He then put 1" wide pine flooring on top of it. Obviously you can replace the plywood with the "car-siding". Is that like a v-groove type of ceiling board? I'm not familiar with the other products you've mentioned, but I think having the thermal mass of the gypcrete is good for radiant heat.

I am going to try a similar thing but use sand and clay mixed for the mass.

Craig, I suspect without insulation under the reflective side and the additional 1-1/2" of wood on top the you may not see the performance you may like to see. You may have to run hotter water, but with an wood boiler it may not be so much of an issue. Wood not being a real good conductor of heat, bordering on insulation itself.

I am going to use narrow board, 4" or so, wide.

I have thought of not covering the clay/sand mix, too, maybe in the bedroom. Less traffic.

Here is another idea.

From the top-down:

~3/4in. Maple flooring
~3/4in. Plywood cut into 12in x 8ft pieces with 30 deg. bevel to hold tubing.
~3/4in. T&G pine
~6 x 6 joist

http://s453.photobucket.com/albums/qq254...office0312D.jpg

I am thinking that I might be able to make my own radiant plates out of used printing press plates.

Might be too expensive fo you - look up warmboard. It is a subfloor with loops molded in, and it uses a thin metal layer laminated to the tip surface. Tubing runs into the molded loops.

You'd have your joist, ceiling material, warmboard, then finish floor.

Craig, how high is the ceiling/floor from the first floor which you are trying to heat? Are the second floor rooms walled off or is there cathedral ceilings allowing air movement? You say the first floor is radiant, you may not have to heat the second floor, or just install some hot water base board or radiator. There are some nice new radiators on the markets now or find and old cast iron one. The heat load on the second floor would be far less than the first floor.

I am under the impression that you need at least a reflective air space, or insulation of some substance to keep the heat in the direction desired. I don't see any reflective or insulative material in the second version. Warm board is wicked expensive.

Thanks guys. This kind of feed back is just what I was looking for!

bmike I did look at the warmboard. That looks really slick!

Tim, I'm thinking of using Arma Foil.
http://www.energyefficientsolutions.com/rbproducts.asp

As I take in all these ideas, I am curious to know if I were to:

~ Nail down the T&G pine ceiling boards
~ Cover pine with a layer of the Arma Foil
~ Nail down the beveled plywood sub-floor
~ Lay 8in strips of foil over the grooves
~ Push plex tubing into grooves, trapping foil
~ Install hardwood flooring

Am I getting closer?

I also wanted to describe the building layout. The barn is a 28ft x 40ft three bay timer-frame. The first floor will be fully open except for a couple of small rooms (bath, storage) with a couple of heating zones, and will be used minimally. I can access the first floor from the basement. The center bay has a cathedral ceiling with a possible wood burning stove. The west end bay will have an open loft with a heated floor with it’s own heating zone. The east end bay loft (14ft x 28ft) will be used the most as a farm office/study. It will have a partition wall separating it from the center bay. The height of the first floor ceiling below the loft is just under 8ft. It is this bay that I am trying to design the heated floor system for.

Rooster

All of the foil insulation products need airspace to do their thing. Sandwiching it between pine and plywood will not give you the desired effects.
How about
-heavier pine ceiling
-1" or 1.5" of Polyiso insulation with routered out pex channels

-printing plate transfer plates
-heavier finished floor

Graig,

We are currently dealing with a radiant floor heat in a 1780's Cape in western Mass. We have used Climate Panels on other jobs, which are similiar to warmboards. It makes for a neat install, but I always feel there should be some insulation to help prevent heat lose. Plus nailing the floor itsself can become an issue, as you are bound to the spacing of the panels. I have also worked with the system Dave described, but would you need to increase your joist size to help support the added weight of the gypcrete?

As for the Cape, to limit an increase in the floor thickness of the original house we omitted the ridgid insulation and layed 3/4 inch tubing on the sub-floor. We then layed 5/8 inch plywood strips in between the loops for nailing. The heating contractor recommended this to ensure that the 1 inch wide pine floor would have full contact with the tubing, thus creating the optimal heat distribution. Of course that then leads to the expansion and contraction factor. The flooring was delivered at 5% moisture content. I will add that I personally would still include a layer of 1 inch High-R ridgid insulation between the ceiling boards/sub-floor and the tubing. Just to clearify this is the system I would recommend:

1 inch Shiplap or t&g sub-floor with a finshed side for 1st floor ceiling

1 inch ridgid insulation

3/4 tubing (confirm exact product with HVAC/ Plumbing Contractor)

5/8 plywood strips layed between tubing loops

1 inch softwood flooring (I think any hardwood would move too much with this system) Hemlock may be a good durable choice

I hope this helps. Good luck. Keep us posted on how it worked out.

Dan

I've used climate panels on jobs as well, and it's a slick, but very expensive system. They even have proprietary caulking with aluminum in it that goes in the grooves before the tubing.
http://www.viega.net/productcatalog.html#model-group284639617504

Lots of people in my area make their own climate panels by ripping 1/2" ply to 6" strips. I think you can even buy the rounded corners, but you can also just route them in situ. The tubing is typically 5/16 or 3/8". My recommendation would be (from bottom up): framing, subfloor of your choice, 1/2" tubing panels, and finish floor. You need to keep the tubing pretty close to the finish floor for the system to be effective. The finish floor shouldn't matter, as long as it's really well acclimatized.