Radiant floor heating retrofit in old floors?? Anyone done it?

15 years ago

My dad -the architect- says it's "easy and not that expensive" to retrofit and old house with radiant floor heat underneath the existing old hardwood floors... from the basement, PEX tubing under the subfloor.

We have existing hot water baseboard and are renovating the first floor opening up rooms to make open floor plan, and losing walls for baseboard. It sure would be lovely to have radiant floor heat in the new kitchen/sitting area!!

I looked on line, though, and only found vague mention of this type retrofit. Anyone done this? Was it difficult or expensive? We're DIY-ers and DH does all the plumbing, so we can do that work ourselves... but what about cost?

If you did it, how's the heat through all that wood? Are you happy with the results (or would you advise sticking with the baseboard?)

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yzguy

15 years ago

I was looking into the same thing but I already bought hardwood oak. They say you can do radiant but you have to be careful of cupping and shrinking...you cannot overheat it. The smaller the width of the wood the less you have to worry about cupping.

I have my floor completely tore up so I can lay a subfloor with the radiant above it or retrofit it...i was told to put the tubing above the subfloor if i wanted to replace my radiators or i could put a smaller tube in, either above the subfloor or under, just to keep the floor warm. My uncle has radiant heat and it is sweet but his floors are engineer wood so he has less to be concerned about.

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Comments (8)

davidro1
15 years ago
Nobody ever says they regret it and that they wish they had baseboards again.

With a bit more web searching you will find many sites that discuss how to do it.
Once you find a couple, they will help yo figure out which new key words to ass to your searching.

HTH
-david
User
15 years ago
Radiant heating doesn't always work well with solid wood flooring. Engineered wood isn't as succeptible to the shrinking and cracking that solid wood can show. You will need to maintain optimal humidity control in your home for sure. That means a whole house humidifier in the winter months. There are a lot of other pros/cons to retrofitting radiant that I'm sure you will research.
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rjoh878646
15 years ago
Below is a link to just one of many companies that make radient heat equipment. I believe they have plenty of info on a retrofit installation

Here is a link that might be useful: Radiantec
azraf
15 years ago
Now a day everyone want to use this floor heating technology. It is becoming one of the MUST have features of the house. Its becoming an essential part, not a luxury. You can get some free educational link from the site i mentioned bellow.

Here is a link that might be useful: http://www.warmyourfloor.com
MongoCT
15 years ago
I did my mother's house a couple of years ago. Single story house with full access to the underside of the floors via the basement.

Her subfloor was wood plank on a diagonal with a mix of hardwood and underlayment and linoleum tiles over that, all 1950s original. Maybe 1150 sqft.

Did two runs of PEX per 16" oc joist bay. Staple-up. No Al plates. Added foil-faced polyiso under the PEX, tucked up against the staples.

To the oil-fired heating system, I needed to take the 180 degree baseboard water down to a more RFH-friendly 120, give or take a few degrees.

I used Tekmar controls. A boiler/mixing control. A 4-way mixing valve. An outdoor reset. A couple of thermostats, a couple of temp sensors, A couple of Taco valves and circulation pumps. One manifold.

Materials ran somewhere around $2000-$2500 for everything.

Wood is roughly R1 per inch. I shoot for three times the R-value below the pex that what is above the pex.

Mongo
janedibber
15 years ago
we did a staple up. mongoct nailed the desciption of what was involved. I would recommend some other things
- get an accurate heat loss calc completed
- use aluminum plates if doing staple up under the joists. it will keep supply temps down and minimize striping
- use R19 insulation under the floor

I would assume the Rvalue and use of plates would be dependent on the outcome of the heat loss calc.

is it easy to install, yes...but also very time consuming. If you don't have the right tools, it will take even longer.
Stacey Collins
Original Author
15 years ago
Great info, folks, thank you so much!!

Radiant floor heating retrofit in old floors?? Anyone done it?

yzguy

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davidro1

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Radiant floor heating retrofit in old floors?? Anyone done it?

yzguy

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davidro1

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