In Slab Radiant Heat

[rubicon1]

Hey Everyone,

I was hoping you guys could help me with a few questions. I am currently in the stages of building a shed that is a 60X80 and I was going to section off a 32X60ft part and put a bathroom, kitchen, and workshop in this area. The total square footage of this part would be 1800 sq ft. I was hoping to heat this part to a decent temperature throughout the year and thought about running pex in the slab. How much 1/2in pex would be required to do this space?? Also, I have a Volcano 2 Woodstove with a hot water heat coil in the top and thought about running this for this winter and maybe getting a Garn or EKO for next year.... any advise on what to do?? or how to hook up this stove??

Thanks,

Luke

 

[rubicon1]

OK, I know some of you guys have put radiant heat floors in before..... no one can offer any help on this situation. My thinking was that putting the pipe on 12" centers it would take appoximately 1800' of pipe. I would buy a couple extra hundred feet just to be safe, but is this the right way to think about this or am I completely missing the boat here?

Thanks!!

Luke

 

[Donl]

I have been told that the rule of thumb is 1 linear foot of 1/2" pex per square foot of floor. No single run should be greater than 250 feet. For my 24 X 32 foot shop I installed 3 X 250 foot runs. I really won't know how well this will work out until I have heated the shop through one season.

Don

 

[steam man]

Hey Everyone,

I was hoping you guys could help me with a few questions. I am currently in the stages of building a shed that is a 60X80 and I was going to section off a 32X60ft part and put a bathroom, kitchen, and workshop in this area. The total square footage of this part would be 1800 sq ft. I was hoping to heat this part to a decent temperature throughout the year and thought about running pex in the slab. How much 1/2in pex would be required to do this space?? Also, I have a Volcano 2 Woodstove with a hot water heat coil in the top and thought about running this for this winter and maybe getting a Garn or EKO for next year.... any advise on what to do?? or how to hook up this stove??

Thanks,

Luke

First of all, a 60 by 80 sq ft building is more like an aircraft hanger, which is a little more than a shed. I had to chuckle at that one. But anyway, I installed the polybutylene tubing in my basement floor long before pex was thought of. There wasn't much for design services or even the internet to research things so I just winged it. Since under slab radiant tubing is more or less permanent, you get one shot at it. I suggest you use a commercial service for your project. There's plenty of online supply places that even offer free design plans for projects like this. Once it is in you can pretty much do any heat source.

Mike

 

[cvanhat]

i live in upstate ny and we have a 52 x 60 steel framed building with in floor radiant heat. we worked with a local supplier and he helped us design and we installed the system ourselves. we used 5/8 pex in 500 foot loops. and before all the radiant pex experts go nuts about loops being to long let me explain why it was done this way. first off, it is a 52 x 60 building, and running 250 foot loops would mean at least 14 loops in the system. also not as much heat is needed at the center of the building, so in that are the loops area spaced farther apart.(18in) also it is a mechanics shop, we fix tractors and farm equipment and the building is normally heated to about 60-62 degrees. sweatshirt temprature. we also have a office that is heated to about 68-70. i dont think it would take much to heat to that temprature with wood. we have oil presently but wanna switch it over some day.we put a eko 200 in the house and plan on running it out to the shop next year. there is no way you would need someting like a garn to heat with radiant. a small eko60 with some storage would do fine. problem with the smaller eko is a short burn on a load. if you have any questions just let me know.

 

[oliver5528]

I have a 26 x 30 addition w/ radiant heat and i used 3/4" pex at 18" on center. I put 4-300' runs in the cement but I have read that you can go up to 450' runs with 3/4" pex. Here is a site that might help you http://www.radiantec.com

 

[DenaliChuck]

The number of feet needed depends on the insulation of the building and the heat load needed. As steam man said, because its in the slab you've got one shot to do it right. Try a supply house, or consider hiring someone for just the design work.

For my well insulated house in Alaska, the spacing for 1/2" pex worked out to be 6" centers for three runs around the perimeter and then 12" centers for the interior runs. Your situation could require more or less, depending.

I was told to use 300' runs max, and 5/8 tube doesn't provide much more heat than 1/2 (just less friction I think)

 

[Willman]

any advise on what to do??

What type and how much insulation do you propose under and around perimeter of slab ?
Will

 

[DenaliChuck]

Only you can decide...I always go overboard on insulation since it is a one time expense that saves every day you heat the structure.

I did 4" for 4' around the perimeter under the slab and 2" under the rest of the slab. I also did 2" outside the foundation at a 45* angle from the top of the footer.