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Radiant heat

Lou Miller
Lou Miller Member Posts: 51
I was wondering if I could get some input from you guys about doing a radiant system for the woodworking shop I'm about to build. I know a lot of you frown on HOs doing this stuff. However, I've been in the trades (not plumbing or heating though) for 20 years, so I'm quite a bit different than your average HO. Also, I just spent all the money I had for the shop's heat on the house heating system (hired that out instead of doing it myself and just can't afford to hire it out again), so I've got no choice but to do it myself.

The shop is going to be 35x60 and built on a slab. It'll have 12 foot ceilings, so that's my main reason for wanting the radiant heat. The heat loss will be very minor as the walls will be built to r-25 and the ceiling will be r-44. It's only going to have a few windows and the doors will be sliding doors that are very well insulated instead of a regular roll up type door.

What I was thinking about doing was tapping into my existing house heat for the shop. I just had a new oil system installed. Crown ct-5 boiler and 53 gallon Mega-Stor with a 6 zone taco system on it. I've got one zone that is currently not in use. I was thinking about running a supply and return about 6 feet underground (well insulated to prevent as much heat loss as possible)from the house to the shop (about 70 feet away). My thinking was to install a smaller Mega-Stor (maybe the 26 gallon) in the shop and then run 1/2" pex, with a circulator and t-stat, throughout the slab from there. I just thought that the aquastat on the indirect WH would be an easy way to control the water temps running through the tubing (water coming out of the boiler is 190). I'm guessing, but I think I can get all of this done for somewhere in the neighborhood of $2000 by doing it myself.

Does the above sound like a sensible plan, or should I go another route? How about a website that I could read up a little on? Or maybe suggest a good book from Dan's collection that I could purchase?

I'd really like to hear any comments from you guys. Thanks in advance.


  • hr
    hr Member Posts: 6,106

    a mini tube injection system. Of course do the heat load first. I'd bet you will see a load under 40K for that space. Got enough boiler capacity?

    With a mini tube you may be able to pipe that distance with 1/2" pex! Put it in a well insulated sleeve, I use some Insul-Sleeve for this. I don't know that 6 feet under is really needed!

    You may want to use a HX to glycol the entire garage system seperate from the house, for freeze protection should a component, or the power fail!

    hot rod

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  • Lou Miller
    Lou Miller Member Posts: 51

    Any site, or book, that you recommend where I could read up a little on the mini tube injection system? The Boiler we had installed was deliberately oversized for the sole reason that we knew it was going to heat the shop as well. Not sure how this works, but the tip that is in the Riello burner is a small one and we can always change that out (did I explain that right? That's how it was explained to me) One of my main things is I don't want any type of flame in the new shop since I spray lacquer and stuff on occasion. That was the reason for thinking about the indirect WH.
  • Lou Miller
    Lou Miller Member Posts: 51

    Thanks, Hot Rod.
  • Kal Row
    Kal Row Member Posts: 1,520
    also Lou:

    get a tekmar 510 tstat wtih a slab sensor in there and give the slab 16hrs to come to temp and keep it there - you dont want to xpand a slab from scratch faster than that

    radiant is the best but also the slowest - i wont do household radiant without scorched air backup - cause people just dont get it!!! they expect instant heat
    so i use two stage tstats - stage two, kicks in the hot air also for instant comfort -

    sorry... just a dose of reality
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