radiant advice...

[Swampy]

I am just about to start building a barn/shop/house structure of my dreams and will eventually be where I hope to retire. Basically 44x60 and I was hoping to have the option of heating the whole thing at a later date. The house will be 36x36 with about 2/3 loft. It will be built on a monolithic slab; vapor barrier, 6" compacted gravel, 2 inch rigid insulation, and 4 inch floor except for the thickened edges. R19 walls and 38 ceiling, vaulted about 1/3 and lots of glass exposure and potential heat loss or gain.

I know this is not the way to do things (kinda winging it) but this is somewhat of a last minute change and my only concern is getting pex in the floor and figuring out the heating details at a later date. *** backwards- I know, but Im trying.

Anyway, for the mono slab Im guessing 10-12" loop spacing and 300 'runs to keep balanced. 5 loops in the 36x36, and 4 in the 26x44 portion. There is a 7" drop from the house floor to the shop floor and I will insulate between as well as under slab and perimeter.

I need to order manifolds and tubing asap and be ready to pour in 3 weeks. I think I need pex-b? and manifolds I can pressurize before and during the pour?

My concrete guy is helping me, but he knows nothing of radiant, so I am in charge of this portion. I understand we want the 1/2 inch pex about 2" from finished floor?

Any advice is sincerely appreciated- just dont scold me too bad, huh!

Thanks



Also this will be built in Central Oregon; 0 winters and 100 degree summers norm.

 

[ixlr8]

You might want to keep your loops in the 250' range, 300' is pushing it unless you go to a pump better than the standard Taco 007, or equivilant. You need to do a heat load calculation and take into account what you are putting on the floor. Is your floor covering going to be slate, stone, carpet, rugs, hardwood, engineered wood, laminate.. they all affect performance and sizing.

 

[rburke65]

You might want to callsomeone that does this kind of thing for a living....a professional.....could be in your home town or anywhere....Google is your friend....I'm sure they can answer all your questions. This is something you want to get right the first time as there is no re-doing this once it's in....ya could but if you had that much money you would be just writing the check at this point.

 

[KenB]

I second the suggestion to find someone in your area familiar with hydronic radiant heat. If you want to hire a contractor for the installation of the eventual heating system and controls, it will help to get their input from the start. Other suggestions I have are 1) use oxygen barrier PEX, so you can use a real boiler and cast iron pumps and 2) plan ahead for any floor penetrations when you install the loops.

Good luck.


Ken

 

[Swampy]

Thanks, and I agree I need a professional and a heat loss calculation. The problem is I dont know all the doors or windows and such for an accurate calculation. I am just trying to get a safe spacing (I think 8 to 12 inch) to give me an option of building a proper radiant system around down the road.

Thanks again-

 

[72Tunaboat]

Where in Oregon? what is the average temperature in the winter?

 

[Swampy]

Central Oregon high desert- temps usually around 20 or so in winter but as low as 0

 

[72Tunaboat]

With cold average temps throughout the winter, These numbers will more than adequate.

Living Space 9-10" apart on the loops

Bathrooms. 6" spacing

Bedrooms. 10-12" spacing

Garage/Shop12" spacing

all with at least 2-4 loops at 6" spacing along exterior walls.

PM me if you have any questions.

 

[Swampy]

Also is oxygen barrier pex what I need to be able to run the glycol antifreeze and cast pump?

Thanks

 

[Dkramer]

You need oxygen barrier pex no matter what pump you run. The oxygen barrier pex is the same as any other pex, except for the barrier. Regular pex will allow oxygen to pass thru it. You do not want oxygen to be in a hydronic/radiant system. Air vents air important. I agree with 72Tunaboat, except that if you are going to have carpet anywhere, to have your space a minimum of 9". With carpet over the slab, you can get cooler feeling areas between the loops if they are to farther apart. Not a heating problem, just a comfort problem.