Garage floor heating help

Old 12-17-09, 02:48 PM
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Question Garage floor heating help

Hello all,
I am new to this sight and have a question on installing a garage floor heat system. My wife and I just bought this house and it has a nice garage that is 24' by 48' long, with the back half (24x24) being newer. When the back half was built the owner installed some sort of solar in floor heating. He had two large solar panels on the south side of the roof and somehow circulated the water/antifreeze down through the tubing in the floor. Most of the system is gone with the exception of the floor tubing which is like nothing I have seen before. It consists of a supply and return loop of 3/4" pvc that transitions up to 1 1/2" pvc with holes that were drilled all the way across (24') each (supply and return)1 1/2" pipe. In each hole a nipple was installed and the floor hosing attached to the nipple. Each hose is spaced about 8" apart in pairs. Each manifold runs along the back wall of the garage level with the floor laid in a cavity that was poured when the rest of the floor was poured. The hose appears to be 1/8" vacuum hose and is buried about 2" down in the concrete. I will attach pics if I can. Has anyone ever seen anything like this before? I would like to build a pump/hot water heater/expansion tank system and utilize what I already have if I can. Any help or recommendations would be greatly appreciated. Picture url's attached.[IMG][IMG][/IMG][/IMG][IMG][/IMG]

Last edited by smokinit; 12-17-09 at 02:51 PM. Reason: url attachment
Old 12-17-09, 05:41 PM
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A few things to worry about.
1) your going to have a heck of a time flowing any GPM thru that 1/8" pipe.
2) there is not going to be a oxygen barrier on any of that, so you will need a propylene glycol solution with rust inhibiters in it.
3) Infloor in garages will aggrevate road salt encrusted cars, not sure if that is a concern.

If you want to heat it, a better bet would be a nice hydronic unit heater.
Old 12-17-09, 06:12 PM
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Now that is home-grown. Don't bother with it, for the reasons TOH said, and then some. You'd need to isolate it with a flat-plate heat exchanger because it doesn't have an oxygen barrier. You don't know if there's insulation under it. The tubing may be crushed and not flow much if at all. The tubing is probably too small anyway.

I concur with TO. If you want to heat the garage, your money would be best spent on a well-sized unit heater. Do a heat loss calc for the space and you're on the way.
Old 12-18-09, 05:17 PM
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Question Re

Thanks for the recommendations guys, I really do appreciate it. Since I have no gas ran to the garage, hydronic (electric is out of the question) is really my only option at this time and I will probably buy a hanging unit. The garage is divided in half with the infloor heating side being the workshop. After looking a little closer at what I had, I discovered that the hose is actually 1/4. So in short I have 1/2 supply and return, just split into 1/4 hose for whatever reason he did this I really don't know. There are 54 hoses spanning an approximate 20' loop (supply and return), so 40' total. Since I am going to have to buy a pump and heat source for the hanging unit anyway I may go ahead and see if I can make the floor system work. I had already planned on running a water/glycol mix in case I lost power so I am not sure if an oxygen barrier will be a problem or not, again I am new to this. No cars other than project cars and motorcycles will be parked in this part of the garage so I am not concerned about salt, hopefull they will never see it. Any other words of wisdom would be greatly appreciated. Thanks again!!
Old 12-18-09, 08:42 PM
Join Date: Jan 2009
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Whatever you choose for heat supply, make sure it has some type of protection for loss of fluid (in case that homebrew system blows out and dumps your system). Some kind of Low Water Cutoff or pressure switch, thermal switch.. something..

I have in-floor in my garage.. I only keep it just above freezing in there, but still.. you can work all day in just runners and you dont get that cold-concrete feet thing.. its great. Hope it works out for ya !

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