Radiant Floor heating within a finished ceiling/ floor.

[Rooster]

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

 



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
 

[Jim_Rogers]

Have you discussed any of these ideas with a professional radiant heating person?

[Rooster]

I have spoken with one, but since it didn't look like a "duck" or quack like a "duck" he wasn't interested in geting involved.  I will probably contact others in my area, I just wanted to have a preliminary plan to show them, and I don't want to have to "re-invent the wheel" everytime start a unique project.  

I am just looking to see if anyone has done something like this, or if I am missing something in my initial design.

Thanks,

Rooster

[Ron Wenrich]

I put in a Stadler system about 15 years ago when I converted my summerhouse into living area.  I'm running an oil burner, but your application would probably do as well.  I put it over the subfloor, then there is a 1/2" plywood series of grooves that you put plex tubing in, then the floor of your choice.  In the bathroom, it went under concrete board and ceramic tile.  Nice and toasty.  In the rest of the area it went under a 3/4" cherry floor.  Works good, unless there is a hard wind.  Old house.

Stadler was a German company.  They seem to have merged with Viega.  I saw this system on This Olde House many years ago.

Here's some examples:

http://www.tjsradiantheat.com/radiantheating.html
http://eandemechanical.com/radiantheatinginstallations.asp
http://www.launstein.com/radiant-heat/radiant-manufact/radiant-manf-home.htm   Lots of links for what you're doing.

[beenthere]

Rooster
Appears you have sandwiched the heat into a thin 3/4" plenum with 1 1/2 inches of solid wood above. To me you have a well-insulated box around your heat tubes. I can't put my finger on it, but doesn't look like a good way to transfer the heat from the tubes to the room above.   It just seems....

[sprucebunny]

You might look at Reflex insulation. The foil-bubble-foil stuff. It would go under the tubing as they usually recomend insulation under the tubing. I have radiant under a 1" thick plywood floor and it works great. There's 3" of fiberglass under it.
The aluminum heat spreader plates are expensive.

When I did it, they recomended clips that held the tubing 1/4" below the floor. Not sure how you are going to position the tubing in a small space.

[shinnlinger]

I cut a 4 ft roll of armafoil (think tyvek tinfoil) into 6inch rolls with my chop saw and stapled pex tubing to the bottom of my main floor with an air stapler.  Reflective, Fast, Cheap and easy.

For my second floor of my timber frame, I put ripped 2x on center(1-1/2 x 1-1/2) on top of my 4x8 floor joists and then pre painted drywall and set them down in each bay form the top.  This created a 1 inch space which I will run pex thru before I put subfloor down.

Dave

[Holmes]

 Hi Rooster  Your design will give more radiant ceiling heat than radiant floor heat meaning it will heat both areas. You need to insulate below the tubing to drive the heat up thru the floor. Your floor has an r value of 1.8 the ceiling has an r value of .9 so the heat will go down. 1" of foam board under the tubing will work , double pipe each bay and suspend the pipe from the floor .  I can go into more detail if you like. I have installed hundreds of radiant heat systems.  Holmes

[Rooster]

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

 



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

I am open to any number of ideas.  I guess I would like to keep the thickness of the floor system to a minimum and also maximize the effectiveness of the heating system.

Thanks for all the responses.

Rooster
 

[shinnlinger]

Rooster,

Did you see my post on the Arma foil?  You will not find a cheaper, easier way to radiate heat.  Sure you can make a jig out of plywood and smash rebar in your printers plates for a few hours and then cut and piece them together underneath one at a time, but with those rolls of foil(again, think tyvek tin foil) you just pinch the pex and staple away for the whole run between the joists.  A 1000sf roll was about $130 and I just cut it into 6 inch widths on my metal chop saw.  They sell narrow rolls for more money if you want.

For your second floor, put the foil down underneath your pex.  

Dave

Dave

[ballen]

Hi Rooster,
Look at:
www.warmboard.com
It's basically plywood subflooring with the pex grooves pre-cut and the whole thing covered in aluminun.  Get's the heat right up just under the finished flooring.
I have a sample and it looks pretty good.
Bill

[shinnlinger]

I wonder how much that warmboard costs?  Looking at it though, I will suggest that you can lay your v grooved subfloor as planned and then roll out the entire 4 ft wide rolls of arma foil and then press your pex down into your grooves. 

[Holmes]

   Warm board is a designed system . You show them your layout  they design and sell you the way to lay it. It's 1 1/8 in thick and is the sub floor. $$$$   Your second design is better. You can use shinnlingers idea or put 6" aluminum flashing down under the plywood  centered on the opening and then silicone the tubing to the aluminum.  Ideal spacing is 8" but if you are well insulated you can do 12" .You should  use tubing with an oxygen diffusion barrier to protect your indoor boiler. 1/2 " tubing max overall length is 400'. you will still get some heat migration down to the rooms below without some type of insulation below the tubing and that may make it difficult to control the first floor heat.  Now if you have a room that needs additional heat you can put in radiant floor and radiant ceiling heat, or you can put it in a wall.  Viega and Upinor make a staple down product that 5/16 tubing fits into 7"X 48" about $11 each also quite expensive.  Holmes

[red oaks lumber]

is a 6x6 2' on center strong enough to carry that load with out bouncing when walking across your floor? depending on the span a 4x8 will give more strength. just my thoughts

[Rooster]

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

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

Dave,  What kind of Arma Foil did you use?

Arma Foil
Arma Foil VB
RB-RES
http://www.energyefficientsolutions.com/rbproducts.asp

Holmes, You have taught me that I have a lot to learn.

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 timber-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

[shinnlinger]

I used the foil as I didn't need the vapor barrier, but the rb res looks even cheaper and should be just as effective.  Maybe ask if it is as malleable as as the foil.

[Holmes]

 Looks good to me . You could put the foil under the plywood for the tubing  instead of on top. It's job is to help get the heat out of the pex tubing and spread it across the floor.  Holmes

[shinnlinger]

Here are some shots of what I did.  I ripped 2x4 in half and nailed them OC on the top of my joists(4x8).  This created a space that I put prepainted strips of 5/8 sheetrock.  Saved a ton of afterward ceiling painting and was way cheaper than cardecking, and who needs to look at a wooden ceiling in a timberframe?  Also reflects light better.  The big plus though is  it also left a 1 inch space that I can run pex and wiring in.  Subflooring will go on the riped 2x

[Rooster]

Dave,

That made a nice looking ceiling!

What did you use to position the tubing between the drywall and the subfloor?  Did you use any radiant plates to spread the heat along the underside of the flooring?

Thanks for your help!

Rooster

[shinnlinger]

I haven't put the pex down yet.  I was thinking of no foil because I didn't put enough pex under the main floor so ceiling heat wouldn't be a bad thing.  I figure heat rises as well and usually you want bedrooms to be cooler.