Installing Radiant in my garage, I have a bunch of ? head is spinning

[JOE G]

Hi, I am putting up a 28 X 28 Garage, first floor will have 10 Ft ceilings, the Second floor is just for storage and will have 8 Ft Ceilings, The first floor ceiling will be insulated.

I am getting a 1000 Ft roll of 1/2 In tubing and will be putting down the insulating tarp below it.

I am not adding the actual heat source yet, prob will do that next year but want to get the pipes run now.

I won't have a full time water source out thee for a while I can reach it with a hose to charge the system.

What kind of heater should I use? I have choice of electric and LP, I am unsure if I should use a 40 or 50 Gal water heater or a Instant Heater Elec or LP?

Thoughts? Thanks

P.S is Radiant even the way to go, I plan to keep the heat around 50 Deg I don't want to spend a fortune to heat the place, Just want to keep stuff from freezing.

If I was going to be out there for a while how long would it take to raise from 50 Deg to say 65 ot 70? if out side temp say was around 30 Deg.

 

[cmhyland]

How about solar? Solar heating hot water is pretty efficient these days and the thermal mass of the slab will keep the garage toasty.

 

[JOE G]

Solar Would be nice option I guess don't know much about it.

 

[EHR]

Since you haven't built it yet, earthberm it. It will stay above freezing whether you have power or not.

 

[BHD]

this is my suggestions,

First I would put in an antifreeze solution,
I not sure you will get the efficiency from a hot water heater you want, I would really suggest the proper boiler,

If you said it I am not seeing it, my guess is your putting this in the concrete floor,
one of the other problems is rapid heat adjustment will not be very easy, as your heating a mass, and the mass will heat slowly, and then the mass heats the air,

but if the mass is warm it will feel more comfortable than the air warm and the mass cold,

you may want some type of air heater to rapidly warm the air,

as far as the fuel type, I would do a little study to see what system would be the lower cost,

but a solar panel may be a consideration, (even a DIY unit and a thermostat and circulating motor) maybe able to do a lot of the heating
situate it to the south, (roof or wall) basically an insulated box, with a black sheet of metal in the middle, with tubing on it to transfer the heat, to a fluid with a thermostat in the box to run a circulation pump when the panel is warm enough to help it kicks on and heats the floor, with just the power of a small pump,

the day time heating needs and the floor holding mass, (the panel, may heat the majority of the needs of the building), some would depend on the size of the solar panel,

I would most likely use propane if it was my building,

 

[Bob Wright]

summary...Glycol solution....boiler wood/fired or gas fired......keep mass on fairly high heat setting...takes a long time to go from just above freezing to nice warm temperature.

 

[megaboz]

I am getting ready to build a 36x40 garage, with 14 ft ceilings. Depending on how much work you want to put into it, you might consider other options. One would be a waste oil furnace, obviously you have to get your fuel, but there are probably enough places around your town that would gladly give it to you versus paying to have it hauled away. You can get them in just a blower type furnace, or in a boiler system.

The hot water tank idea, while it will work, it won't do real well in severely cold climates. Now that being said, I would say away from the instant on type of heater. Most likely in the winter time, the heater is going to run 24/7 or nearly. Depending on the price of LP, it would probably be the better option. Gas is going to heat faster if you go with a hot water tank.

The amount of time for it to raise the temps, it will take some time, probably a few hours. However, talking to individuals that have radiant heating systems in their shops/garages, they all claim that they actually leave the temp turned down between 60 and 65 and claim that it is almost too warm still.

 

[jimgerken]

Hi, I am putting up a 28 X 28 Garage, first floor will have 10 Ft ceilings, the Second floor is just for storage and will have 8 Ft Ceilings, The first floor ceiling will be insulated.

I am getting a 1000 Ft roll of 1/2 In tubing and will be putting down the insulating tarp below it.

I am not adding the actual heat source yet, prob will do that next year but want to get the pipes run now.

I won't have a full time water source out thee for a while I can reach it with a hose to charge the system.

What kind of heater should I use? I have choice of electric and LP, I am unsure if I should use a 40 or 50 Gal water heater or a Instant Heater Elec or LP?

Thoughts? Thanks

P.S is Radiant even the way to go, I plan to keep the heat around 50 Deg I don't want to spend a fortune to heat the place, Just want to keep stuff from freezing.

If I was going to be out there for a while how long would it take to raise from 50 Deg to say 65 ot 70? if out side temp say was around 30 Deg.

Good start, you are asking all the right questions.
Divide your tubing into four equal length runs, and interlace them into the floor, so if one is eventually compromised with a leak you can simply block it and run the other three. About 250 feet is correct per run, plus or minus but keep them equal within a few percent.
LP is cheaper than electric in most cases.
A standard water heater should be enough for your application. A power vented one is a bit better cause it makes more heat and because its easier to plumb the exhaust thru the wall in PVC. I have use this method since 1997 in a 28 x 38 in southern Minnesota. It works great. I keep the air temp at 50 and thats enough if you are wearing a light jacket. If I know ahead of time I will be spending all weekend in there, I turn it up from 50 to 60 and it will stabilize in 4-5 hours.
All the above recommendations are based on the assumption that you are going to put insulation under the slab. At least 2 inches of extruded polystyrene is my recommendation, and current code in my area.
My building also does not have water supply. Not a problem, once the system is charged it is maintenance free if it does not leak anywhere.
I do not run any anti freeze. If power goes out, it would take over a day to freeze the water in tubing in the floor, due to the thermal mass. So, my power-out backup plan is (and never had to be used) to drain the water heater onto the floor and let it go down the drain, and then blow out the floor lines with compressed air, which is available at all times in a 60 gallon tank charged to 125 psi right next to the heat system.
If you go with a standing water tank heater, be sure to factor in that extra 40 gallons in the system total, and size the expansion tank accordingly. I'd suggest something about 4-5 gallons size pressure tank (half that is air, half is water), with 1000 feet of 1/2 inch tubing (~9 gallons) and a 40 gallon water heater.
You will love hydronic radiant floor heat. It is comportable (at lower temps that forced air would be), simple, cheap to operate, and fast to recover if a door is opened for a few minutes. Your dogs will also love it.

 

[Dr Dave]

Be sure to isolate outside wall/footings from the slab,with pink foam board, also put it under the slab. Floor heat is so efficient that you may leave it up more, say 60 deg. My neighbor heats a 38'x70' pole building with an electric, on demand, water heater. It has 2 zones, and is divided, living space and shop, he is very happy with it.

Dave

 

[Gils]

I would take a look at solar water heating. If you are handy, take a look at the following website, it will give you plenty of ideas.

BuildItSolar: Solar energy projects for Do It Yourselfers to save money and reduce pollution

 

[Bob Wright]

I installed an electric 4 chamber boiler. I heat up all of my floors at night when hydro costs are less and turn it off at 7 a.m. (down to 60) Even at 20-30 below outside it only drops a degree an hour during the day......assuming all entries are closed for the majority of the time......I'm building an outside wood boiler/furnace/oven outside next summer....got lots of dried wood that's free and it will be a multipurpose device for cooking/baking/barbequeing...cheers

 

[jimgerken]

A few more things.

Before you divide your 1000 feet of tubing into four equal lengths, take out a length that would route from the manifold area down into the floor, out to almost the coldest spot, like a few feet in from a door on a north wall. Press a plug (like a 1/2" bolt) into the end to plug it, and tie it into the re-rod grid just like you will do with your heat tubes. Later, when wiring, you will push a slab temp sensor on its wires, down this tube with a snake, to get a temperature reading for your thermostat. This way, your system seeks to keep the slab at the same temp all the time, instead of responding to every cool breeze that happens when the door opens momentarily. Fewer cycles, longer operation each cycle, so more efficient, and more even temps in room.
Attempt to get the tubing about centered in the slab vertically. It would be most correct to put your re-rod grid up an inch and a half, then tubing tied to the top of that, if pouring about 5 inches thick.
I used a deal called a Easy-route. It controls and routes the tubes into the slab and makes it more resistant to damage on floor pouring day. Google that.
Once it is all ready for concrete, hook it all up to a manifold with a pressure gauge on it and a shraeder valve so you can pressurize it with air. Put 15-20 lbs in it and watch it for a day. It should not go down more than a pound due to relaxation of the tube shape. Leave pressure in it while you pour concrete, keep glancing at it. If pressure suddenly drops, the crete workers have damaged the tube. STOP them, have one put the air onto the shraeder valve, and it will bubble out wherever the damage is. Cut the tube on the damage point. Use your splice kit (a double-ended compression fitting in brass), to repair. Have two splice kits in your pocket, along with wrenches. If you have them, you wont need them.
Use a concrete pump if possible. WAY easier on the tubing to have guys walking around on it, compared to having them dump wheelbarrows on it (that stresses me out just thinking about it).

 

[jim_wilson]

Here's how I did it in my 28x42 garage

First the garage is on a full foundation - and the interior was filled in with compacted gravelly sand

The fill on the interior of the garage actually sat for a couple of years before I finally got the chance to put the floor in.

First I prepped the whole thing by lasering a line around the interior foundation wall and marking where I wanted the final floor level to go.

Then I prepped the fill by carefully leveling off the entire area and running the compactor over it a few more times. I leveled the fill by using a long straight board and a straightedge to make sure I had it level and even.

Then I laid down a layer of the Owen's Corning pink foam insulation like you see at HD and Lowe's - BUT- I didn't use the version they sell at HD. Owen's Corning sells that pink foam in a range of different compressive strengths - I think the stuff they sell at HD is the "100" version, I got the "600" version - which has a much higher PSI rating than the 100 version.

A layer of water proofing was laid over the foam. I used this stuff that came in 4x8 sheets and is some sort of asphalt impregnated sheet. The system also has a sealing tape that goes down on all joints. Waterproofing is important - moisture will come up thru the floor if you don't put a waterproofing layer in there. You will find all you stuff rusting if you have a moisture rich soil under the garage.

Then I laid down a grid of rebar with a 2ft square across the whole floor. The rebar was spaced up off the floor by using some of those concrete bricks that I carefully broke in half. This put the rebar at just about the right distance to position the tubing where I needed to be.

Then I laid down the PEX tubing for the radiant floor in sections over the rebar. They say the tubing loops should not exceed a certain distance (can't remember what it is off the top of my head) - so I broke up the garage into 3 sections - pretty much by each garage bay - and ran the tubing back to the central point. I used the rebar to position the tubing by tie-wrapping the tubing to the rebar as I laid it out.

I used PEX tubing with the oxygen barrier in it - specifically made for radiant floors.

Then the concrete guys came in and laid down a 6" thick floor using 4000psi concrete with the fiber reinforcement in it.

I still haven't managed to get the whole thing hooked up to a heat source yet - but I have multiple options. I had also run a length of ThermoPEX from the garage to the house (the stuff that's used to hook up the outside wood boiler systems) - so I can heat the garage using the boiler I already have in the house (once I finish getting it all plumbed up) - or - I could hook up solar, a separate boiler in the garage - etc.

If you need some more specific information let me know - I'm sure I can dig out the information.

 

[JOE G]

I was thinking of doing four loops, I want a heat source that I can keep the temp up enough to keep things from freezing all winter long, I also don't want to spend a ton of money to heat it. If I need temp up quick I can always get a salmander or something like that for a quick heat boost.

I was thinking of doing tankless, I use one for my home a 199,000 BTU and I love it. I would rather pay more now to install and then save in my yearly heating costs, Like I said I just want to keep stuff from freezing out there, I don't care if I can't walk around in shorts.

I figured with a blower type, when ever I opened the big door even for a short time the whole building will cool right off, with the radiant I figured it would recover to a stable point quicker and cheaper.

I figured that it would keep the building at about 50 Deg and do it cheaper per month then other heat sources. Am I wrong about this?

I know the up front cost will be more but I don't want a very expensive monthly bill.

 

[homedad]

I think you're on the right track in trying to keep the slab warm-ish. I have a workshop which was built as a home. It is 1200 sq feet, insulated slab on grade, 2x6 R19 walls, R40 ceiling and vinyl double glazed windows. I keep it at 45degrees due to plumbing. The 100k btu forced air furnace will heat the place to comfortable levels in about an hour but the concrete slab stays very cold and makes the furnace cycle. I have in floor heat in the basement of the main house which is heated via 50 gal water heater. This floor takes about 2 days to go from 58 deg. to 70 deg. It's about 1600 sq. feet and insulated with 3" foam. If you can keep it warm it's great. If you let it get cold it takes a long time to heat.

 

[JOE G]

I want to keep it at a constant temp to avoid stuff freezing in the garage that is my goal.

 

[megaboz]

There are tons of sites that have plans and tips. Let Google be your friend. While I said earlier that a hot water tank wouldn't be sufficient, apparently I was wrong. However, many of the sites I visited really frown on the instant on hot water tanks. Claims I read about them is that they aren't that efficient for that purpose. Don't hold me to that statement, just repeating what I read. But when you think about it a hot water tank stores potential energy and an instant on tank doesn't, so it would probably run more than a tank system.

The lengths mention for the loops is approximately 300 feet. And each loop should be as close to the same length t prevent one loop from greeting more or less flow.

But with that, I read another claim that the length isn't so much important as the ability to get the water from start of the run to the end of the run while only losing about 8 degrees in water temp. What I continue to read about it is for the pump to have the ability to push the water fast enough from end to end to achieve that rate of heat loss. I think the term was called head.

Seriously Google it and do some reading. Generally when I know nothing about a topic I tend not to believe the first site. So I end up reading several of them.

But anyway that is what I know.

 

[henryswe]

I put radiant heat in my house and found it not only comfortable but efficient. This heater, Polaris Water Heater for Radiant Heating is 95% efficient and has a stainless tank to last. I run this tank at 128 degrees and found that is all I need in my 2000 sq foot house. I wish I put that system in my pole building but couldn't afford it. I also agree to Google it and get as much knowledge as I can. It is a investment but well worth it.

 

[doohicky]

Don't forget about the mixing valve to temper the water going into the slab if going the boiler route. I think that the max temp that they say to put into the slab is 115-120 degrees.

 

[dclynch]

I also have in floor heat and use a Electric Mini boiler. I would not reccommend this option. It works great but is very expensive to operate. I wanted to go with a Hot water tank but let myself get talked out of it. I was working out of town and had to hire a guy to hook it up. He told me it wouldnt cost more that 75 - 100 dollars a month to heat my 24 X 40 pole barn. Well he was way off It costs any where from 200 - 300 more. I just asked for a quote from the Polaris Water company. I will say this 60 degrees is too warm for me. When we had parties I would set it at 60 and by the middle of the evening we wereopening windows because it was to hot. Last year I left it at 50 all winter and that seemed perfect it was chilly at first but it would warm up to 63- 67 by the end of the night.