Author Topic: In-floor heat in the garage  (Read 3356 times)

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Volvo farmer

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In-floor heat in the garage
« on: September 10, 2004, 04:01:36 AM »
The project is officially started. I have a 24'x30' framed garage I built last year. Finally scraped up enough money to pour a slab in it and decided to put poly-pex tubing in the floor so I can heat the slab. I had a layer of 3/4" road base on the floor already. First step was to level it out. This is accomplished by 2 people pulling a 2x4 across the surface





Next, we put in 1" of styrofoam insulation. This is the cheap stuff available at the home centers for about $8/sheet. Total cost was less than $200. I would have prefered to use the high density foam stuff but the cost of that is about triple the styrofoam. This insulation is about a R-5 and it should help keep the heat in the slab and out of the ground.





Next comes the tubing. I chose 1/2" Wisboro aqua-pex, it took about 300 feet. This tubing does not have an oxygen barrier but everyone told me I don't need an O2 barrier unless I'm planning on using a boiler to heat it, which I'm not. Aqua-pex is also much cheaper than heat-pex. Tubing and staples were $280 but I could have gotten it wholesale for less. A plumber guy let us use his machine to punch the plastic staples into the foam. There's other ways to secure the tubing but this was very fast and easy





Last, we layed down 6" remesh on top of the tubing. It took about a roll and a half and set me back about $120. The board in the middle is so we can skree the concrete, it will come out once the pour is level.





Thats about it for now. The concrete truck will be out at noon today and I'll have more pictures soon. I have these three big 4x10 commercial solar hot water panels that I want to heat the floor with. I haven't figured out the details yet but my plan is to use some sort of 12V hydronic pump, a small 12V solar panel, and proplyene glycol to move heat from the panels into the slab during sunlight hours. If it works out the way I want it to, I will have a heated slab using only the power of the sun!


Volvo farmer

 

« Last Edit: September 10, 2004, 04:01:36 AM by (unknown) »
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jacquesm

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Re: In-floor heat in the garage
« Reply #1 on: September 10, 2004, 07:21:28 AM »
If you have a big overhead door(s) where you can have a car or pickup enter the building (you did say it was a garage) add some heavy rebar at the entrance, it's the one thing I would have changed here if I could do it again...


« Last Edit: September 10, 2004, 07:21:28 AM by jacquesm »

JB

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Re: In-floor heat in the garage
« Reply #2 on: September 10, 2004, 09:52:21 AM »
 very smart move. I spend most of the time in a cement floored garage and wish I would have done that. The old feet fitted with stainless hardware  just dont like cold concrete anymore . JB
« Last Edit: September 10, 2004, 09:52:21 AM by JB »

ghurd

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Re: In-floor heat in the garage
« Reply #3 on: September 13, 2004, 12:54:01 PM »
I have been thinking about a variation of this for quite a while. It makes me itch that I missed my oportunity (floor poured!) to try it by about a week.


If you have the solar water heaters already, and you are waiting to figure out the rest of it... How about a temporary set up?


Like a 5 gallon pail for expansion, and a marine (boat) live well pump? They are 12 volts, seem to move a lot of water for the power used, and pretty cheap.


Pretty much cold water out of the floor, through the pump, through the bucket, through the heaters, into the floor. A air conditioner type thermostat inside the heater could be set to say 90', so when the temp. get there it would turn on a small (high coil resistance) 12v relay that would turn on the pump.


It wouldn't be fancy. It would be cheap, at least until you get all the fancy controls, pump, expansion tank, etc.


The place I missed was going to be heated with wood/coal, in an area where it may be 40' (fire burning) 3 days, then 60' (cool- but no fire) for 3 days. I was thinking of using the floor to store some of the heat made during the cold days. Solar electric (already there) was to pump the water past the wood burner (already there). I'm not talking anything ground breaking, just more like an experiment. Everything extra would have been about $150. Just plastic and copper (by the stove) pipe, and a pump.(the PV etc. was already there) It would be useless in the winter and summer, but nice in the spring and fall. It's an Amish house (you should see his solar electric set-up!).


Any thoughts as to why this wouldn't be any good?

« Last Edit: September 13, 2004, 12:54:01 PM by ghurd »
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Volvo farmer

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Re: In-floor heat in the garage
« Reply #4 on: September 13, 2004, 04:12:36 PM »
Well, I basically only want to plumb it once. a small solar pump and 5 or 10 watt solar panel cost about $200. Add a real expansion tank and a tempering valve and I'm up to $300 but it's done right the first time, and there's no electronic controls. When the sun shines, the water gets hot, the pump starts and the glycol moves. When the sun goes down, it all stops and the slab stays warm. If it gets too hot, the tempering valve saves my pex tubing from 200+F temps. I'm not living there at the moment so I can't be out there to monkey with things and I sure don't want to be heating a couple of old Volvos and stuff with propane. I'm really hoping to get this done this fall but the building doesn't have any garage doors yet nor does it have any insulation.  

If I get it plumbed before winter, I'd like to use a data logger to see how the performance is. I bet it doesn't keep it toasty warm in January even if I had wall insulation. I've been thinking about eventually using a 6 gallon propane hot water heater from an RV for supplemental heat. Since I'm using a glycol solution and no heat exchanger, I don't exactly want 40 gallons of glycol in the tank.

I'm thinking of using no thermostat and let the temps swing wildly, log it, and go from there. Check it out, A bull(?) snake decided to check out the pour. Those studs are 16" apart so the snake is probably close to 3 ft long.



And yes, I really do farm Volvos.

« Last Edit: September 13, 2004, 04:12:36 PM by Volvo farmer »
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ghurd

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Re: In-floor heat in the garage
« Reply #5 on: September 14, 2004, 03:56:46 PM »
I like the one with the flames.


You might want to look a little harder at the solar panels and pumps. A 5w panel only puts out about 0.29 amps, 10w about 0.59 amps.

What pump goes with those numbers? I'd guess the El-Sid, except for the pump and panel cost of $200.


But be sure to let me know about the pump. I think I NEED some of those.


G-

« Last Edit: September 14, 2004, 03:56:46 PM by ghurd »
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Volvo farmer

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Re: In-floor heat in the garage
« Reply #6 on: September 14, 2004, 05:59:41 PM »
Yeah, I guess I was off a little on my prices, It'll be more like $350-400 for an El Sid pump and panel. Apparently they're good pumps and last a long time though. I thought I found a website with a 5watt pump and panel for about $250 but can't locate it now. 10 watts would probably be better anyway.

Here's a site
http://www.lightheat.com/pumps.htm

They say double the wattage of the solar panel if you're pumping glycol. So a 10 watt panel and 5 watt 2.2GPM pump would run $320 or so. IF you could get away with a 5 watt panel, it would be closer to $250.
« Last Edit: September 14, 2004, 05:59:41 PM by Volvo farmer »
Less bark, more wag.