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

[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.