# hydronic heat under wood floors



## maderuyck (Jan 21, 2005)

I am putting down a 3/4 inch solid wood floor on the main level of a rambler. I plan on running hydronic heat (pex tubing) from the underside next summer. I know that this system is not ideal for a wood floor- my question is would it help the heat get through if I drilled holes in the plywood subfloor every ten inches or so between the joists before I nail down the wood floor?


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## BigMikeB (Aug 1, 2007)

Why not put the tubing in the underlayment now and finish it next year?


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## maderuyck (Jan 21, 2005)

*underlayment*

This is not new construction. I'm pulling up carpet and replacing it with wood floor. Next summer I am going to pull the rock off the ceiling in the basement and run the pex tubing for hydronic heat and I want the heat to go up through my new wood floor as efficiently as possible.


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## MechanicalDVR (Jun 23, 2007)

maderuyck said:


> This is not new construction. I'm pulling up carpet and replacing it with wood floor. Next summer I am going to pull the rock off the ceiling in the basement and run the pex tubing for hydronic heat and I want the heat to go up through my new wood floor as efficiently as possible.


It's more efficient when it is run in the underlayment rather than under the subfloor.


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## 747 (Jan 21, 2005)

maderuyck said:


> I am putting down a 3/4 inch solid wood floor on the main level of a rambler. I plan on running hydronic heat (pex tubing) from the underside next summer. I know that this system is not ideal for a wood floor- my question is would it help the heat get through if I drilled holes in the plywood subfloor every ten inches or so between the joists before I nail down the wood floor?



Thats a big no. The way that is done is as follows. YOu have to buy this special metal which has groves for the tubes. This makes the heat go up instead of down. Finally you then need to insulate inbetween the floor rafters. Best is to spray foam. Finally you can use radiant heating under woods floors you just have to make sure you don't get crazy on the temp. of the water your running through the system. Now i'm not sure about water temp inbetween floor rafters like your talking about but the other method where your putting the floor directly over the radiant floor heating that water would be in the 90's. I think 95 if i'm wrong someone will straighten me out.:thumbsup:


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## MechanicalDVR (Jun 23, 2007)

I have never seen pex buried that deep below wood. Usually the tubing is put into grooved subfloor panels that the aluminum reflectors sit in and the tubing is snapped into them with a mallet. Then the flooring is nailed into the spaces between the tubing @6" islands between loops. The jobs with the heat tubing fished in below the floor in the joists spaces are the ones that always have issues with air traps, low temps in certain spots, hot spots other4 places. Maybe you should take a class in radiant before you make a decision about your install. Many supply houses offer classes for free.


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## rex (Jul 2, 2007)

i did a job 2 years a go....tji joist on 12" centers stapled the tubing from underneth directly to the sub floor.ran the tubing in the same direction of the joist staping the tubing in the center of each space and drilling a hole at the end of the joist for the next loop.....used bubble wrap to insulate and mounted a manifold in the celing near the beam......the area that is heated is cermaic and harwood and it heat's awsome.....no hot or cold spots what so ever.... i went back for a seized disposal took my boots off and noticed the heated floor right away walked through the heated area with the home owner and he had nothing but good things to say about his heated floor....


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## MechanicalDVR (Jun 23, 2007)

rex said:


> i did a job 2 years a go....tji joist on 12" centers stapled the tubing from underneth directly to the sub floor.ran the tubing in the same direction of the joist staping the tubing in the center of each space and drilling a hole at the end of the joist for the next loop.....used bubble wrap to insulate and mounted a manifold in the celing near the beam......the area that is heated is cermaic and harwood and it heat's awsome.....no hot or cold spots what so ever.... i went back for a seized disposal took my boots off and noticed the heated floor right away walked through the heated area with the home owner and he had nothing but good things to say about his heated floor....


What is the total thickness of the sub floor and hardwood?


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## rex (Jul 2, 2007)

MechanicalDVR said:


> What is the total thickness of the sub floor and hardwood?


 
3/4" advantech sub floor and 3/4 inch oak hardwood floor......as for the tile part 1/2 "cement board and 1/4" tile..


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## MechanicalDVR (Jun 23, 2007)

rex said:


> 3/4" advantech sub floor and 3/4 inch oak hardwood floor......as for the tile part 1/2 "cement board and 1/4" tile..


 
I have never seen a problem with tile transferring heat to the room above, it has good thermal mass. Wood on the other hand is an insulator and those jobs I have been to after they had issues and were looking for another opinion.


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## 747 (Jan 21, 2005)

MechanicalDVR said:


> I have never seen a problem with tile transferring heat to the room above, it has good thermal mass. Wood on the other hand is an insulator and those jobs I have been to after they had issues and were looking for another opinion.



yep tile is like the best thing to put over radiant floor heat.:thumbsup:


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