Wood floors and radiant

Dof3

I have never used al plates because they are right next to the floor. I have had nails shot right through the tube that way. Just use the the pex clips that hold it 3/4 inch from the floor.

ray kal

wood floors

I am researching the installation of radiant with wood floors. I once read that there is a problem with having a staple up system when tar paper is between the hardwood floor and the subfloor? Can radiant be used. any suggestions are greatly appreciated.

brucewo1b

The tar paper will get hot and smell best to stay away from radiant unless you want to pull the floor to removve the tarpaper

Dof3

wood floors

I have done quite a few staple up jobs with wood floors without any bad results. The flooring people used red resin paper instead of tar paper. You have to keep the temps around 100 to 110 degrees. I would use a Pergo type floor for best results. But, if that is not an option...

hr

Usually

radiant floor systems run well below the temperature needed to melt down asphalt impregnated felt paper.

But I did once see a high temperature staple up cause outgassing and smell. At my brother in laws home in fact. A thick build up required high temperatures with bare tube staple up.

So it is possible. Typically you should be well below that high temperature, and I would add supplemental heat long before I drove a floor temperature to the point of melting that paper. Most design software will alert you when you start approching that number.

I've done dozen of retro fit radiant under old hardwood with asphalt impregnated felt paper without issues. My own 1960 vintage home is one with felt, hardwood and radiant living in harmony

Run the numbers to determine the BTU's needed and the floor and supply temperatures involved to "get there." The answer is always in the numbers

hot rod

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ray kal

Thanks for the input. I was planning on keeping surface below 85F and using aluminum plates. The rooms
will need some supplemental heat. What would you recomend? Baseboard fin tube or what?

Thanks in advance.

Mike T., Swampeast MO

Will second the Red Rosin Building Paper. LONG used and still easily available.

ALH_4

Plates

Are you using extruded plates or the sheet metal ones? Are you sure you need supplemental heat? In my opinion, to minimize the possibility of offgassing and maybe eliminate the need for supplemental heat you should use extruded plates to keep the floor temp as even as possible and run outdoor reset to keep the temperature as low as possible.

For supplemental heat, I would use steel panel radiators and run them at the same temp as the radiant floor if only a few rooms need supplemental. If there are a lot of radiators, it may be worth investing in a two temperature system to keep the radiators or baseboard smaller.

-Andrew

Josh M.

According to my calculations if you have an 85 degree floor surface temp. and an upward heat flux of 30 btu/sq ft. you would need a supply temp of 163 degrees. Seems as though that is a little excessive. I would think that you would need alot of supplemental heat. In order to drop the supply temp even to 140 degrees you would only get about 22.5 btu/sq ft. of upward heat flux. I have a question fo the experts... What would you say is an excessive average supply temp?

ray kal_2

Hot Rod , what is a maximum temp for the asphalt paper

What is a good maximum temperature of the asphalt paper to prevent the smell? this question is about an older 1940's house

hr

The best answer

would be the lowest possible temperature to meet the heat load Although that's probably not the answer you are looking for.

Can you get your hands on a piece of the paper that is in your home? I'm not sure all paper is created equal. I tried, once, to get temperature info from the asphalt paper manufactures.

The best they could come up with was the temperatures that paper sees under shingles in Arizona! Which seem far beyond what I would expect a radiant floor to need

My idea was to take a piece of the actual paper, sandwich it between the wood build up, then throw it in an electric fry pan (with the women and children outside)

Watch the thermometer and red light on the fry pan and see where it starts to squirm, fizz, and smell. Five degrees below that point would be my comfort number

I'm kidding. Sort of. But I don't know how else to get the info you are requesting without some shade tree engineering, since the folks that made that paper may not be around anymore.

Keep in mind the supply temperature to the transfer plates is probably NOT what the asphalt felt paper is seeing. You still have the subfloor R value to account for.

hot rod

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Josh M.

You know Ray.. If I were you I would really look into wall radiant if possible. I do however like panel radiators like Runtal because you get radiation instead of convection type heat...