Is there any issues with putting radiant heat (staple up from the cellar) under a 40 year-old hardwood floor? We have nice oak floors in the house, and I'd love to have them all toasty, but have heard anecdotal evidence that putting radiant under a wooden floor may cause warping, contractions etc..basically mess up the floor. I had radiant under part of my last house, but it was all under tile, so shrinkage was a non-issue.
Radiant under a 40 year old wooden floor
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While it doesn't appear there is a 'go' or 'no go' answer there are certain things which can help prevent a disaster... This article sums up some issues:
http://www.woodfloorsonline.com/techtalk/woodwater7.html
http://www.woodfloorsonline.com/techtalk/woodwater7.html
Gooserider
Mod Emeritus
Nice link Corey, covers a lot of the issues quite well...
Essentially it can be done, as long as one keeps the radiant temperatures reasonable... From other similar discussions here, one other big issue in staple up retrofit jobs is the question of how thick the floor really is, especially in an older house that might have had multiple layers of flooring installed over the years - Wood has an R-value, and if you have to much total floor thickness, the heat simply won't make it from the tubes to the floor surface at any reasonable tube operating temperature...
Another issue that MAY come up, is that some floors that weren't planned for radiant, may have been built with a problematic building paper between the floor and subfloor, which can cause odor problems when heated....
Bottom line, it's possible, sometimes, but you need to do your homework to see if it will work under YOUR floor or not...
Gooserider
Essentially it can be done, as long as one keeps the radiant temperatures reasonable... From other similar discussions here, one other big issue in staple up retrofit jobs is the question of how thick the floor really is, especially in an older house that might have had multiple layers of flooring installed over the years - Wood has an R-value, and if you have to much total floor thickness, the heat simply won't make it from the tubes to the floor surface at any reasonable tube operating temperature...
Another issue that MAY come up, is that some floors that weren't planned for radiant, may have been built with a problematic building paper between the floor and subfloor, which can cause odor problems when heated....
Bottom line, it's possible, sometimes, but you need to do your homework to see if it will work under YOUR floor or not...
Gooserider
greenheater
New Member
I am on my forth year with staple up on my 12 year old maple floor. 3/4 maple on top of 3/4 plywood running 120 deg water with tekmar tstat and slab sensor programmed to a max slab temp of 85. I believe I got this temp number from the hardwood flooring institute. BTW, 3 inch wide maple. I do get some small shrinkage during winter but the tradeoff is a very comfortable warm floor that I will gladly take. When it gets below say 20 degrees OAT I supplement the radiant with forced air. I'm not willing to crank the slab above 85 and be a test pilot.
I am on my 5th year with 100 year old hard southern pine and 2nd year with 150 year old wide plank with no problems. I run at120* and have occassionally run to 140*. Since you are retro fitting is it posible to keep your ald system intact? I have my forced hot air incase the floors cant keep up or if I need instant heat.
It's the humidity in the room that causes wood to "move", more than just temperature increase.
I'd design to supply no more than 120- 130F. Look for a surface temperature around 80- 82F to stay safe and comfortable. The key is to do a load calc and see if the space can be heated with radiant working at that temperature. if not you may need some supplemental heat on cold, design days.
Don't try to over do with the radiant. 20 maybe 25 BTU/ square foot is a reasonable expectation from a radiant floor. Use the aluminum transfer plates to keep supply temperatures low, and spread the heat evenly.
hr
I'd design to supply no more than 120- 130F. Look for a surface temperature around 80- 82F to stay safe and comfortable. The key is to do a load calc and see if the space can be heated with radiant working at that temperature. if not you may need some supplemental heat on cold, design days.
Don't try to over do with the radiant. 20 maybe 25 BTU/ square foot is a reasonable expectation from a radiant floor. Use the aluminum transfer plates to keep supply temperatures low, and spread the heat evenly.
hr
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