Anybody with experience? I guess it's like boiler heat only it uses capillaries in the concrete. Work good? Pain in the butt?
Shop size will be 40 x 60 with 14 foot walls.

TIA. Peace

 

Expensive on the install due to the tubing having to be laid down before the concrete is poured, along with the boiler and pump costs. In return you get warm floors to lay on that is more efficient that overhead radiant (depending on the boiler) Fill system with glycol if you plan on letting the garage get cold.
Cheapest way is good old forced air, then you can add air conditioning.

 

PROMOTING QUALITY AND AFFORDABLE RADIANT FLOOR HEATING

<CENTER>Nearly one hundred pages about installing and designing radiant floor heat.</CENTER>http://www.radiantdesigninstitute.com/


This isn't an ad since it's all for free. I have found the information here very helpful and thorough. Some locals I have spoken with seem to think the recommedations he makes are overkill, but he says he has designed and installed some 2,000+ systems. He's gotta know something about it.

When you get done reading this I don't think you will have any questions. You have available over 50 pages, with many diagrams, all helpful stuff.

I am halfway through my project, but am hopeful to get it completed for winter 2007-'08. Plan on using a corn-fired boiler since corn is readily available (right now, unless the ethanol plants buy it all up!).

Dave
<CENTER>
</CENTER>

 

Do a search on radiant heating and you'll find many posts about it. I've had it in my garage for over a year with no problems. The nice thing is that you can do it in stages. You can buy the tubing and manifold, and then wait to purchase the boiler and pumps. You can also use a wood-fired or corn-fired boiler if you want. I wnet with a Munchkin boiler that runs on propane, and it keeps my 42'x60'x14' garage at a nice 45 degrees. Of course the slab is insulated with 2" of foam insulation and the walls and ceiling have 6" of insulation in them. Both the access and garage door are also insulated. Go to www.radiantec.com and give them a call. They'll ask you some questions, and then design a system for you.

 

The way I understand it, the 2" rigid foam board is crucial and they one guy I talked to was going to use the foil-one-side bubble (1/2") type insulation. My read of it is that the bubble might be OK if it doesn't get too cold where you are, but for around here, the foam board is the way to go for efficiency.

Do visit the Radiant Design Institute site as well as others. This Fred Seton seems to cover every detail.

 

I'll be doing a radiant floor heat install in my shop(32x40x10) this spring. Since it gets quite cold around here, I'll be using 2" foam under the slab and 4" around the perimiter, 2 feet down. Most heat loss is at the edges, so an extra 2" of insulation should help a lot.

 

Thanks guys.

Ford79, could you explain the "heat loss at the edges"?
Perimeter as in outside of foundation?

Thanks

 

If I can chime in on this a little as I've been thru 2 winters with my shop and in floor heat. 1. Best thing since sliced bread. 2. Leave the thermostat alone. Just set it where you want it and leave it there all winter. 3. Get an adequate boiler. I am using a hot water heater and for me it's undersized. 4. Zone it! That way if you wall anything off you might want it warmer on one side than another. 5. Insulate both outside the floor and under the floor well. The more warmth you keep under your feet the warmer you'll be. 6. You'll be surprised how warm 50-60 degrees feel. Don't need much to be comfortable. I've heard that the 5/8's diameter tubing does better than the 1/2" like I have so there is something to investigate on. I know with the 5/8" you don't run as much or as close together. Good luck.

 

I do not want to disagree with any of the above, but let me share my experience. My shop is large (3,000 sq.ft.) and I had intended to lay the tubing into the slab for heat, but there were so many things going on (& it was summer, so heat was the farthest thing from my mind), that I FORGOT. What I learned may be useful to someone in a similar climate to mine on the east side of the mountains in MD. This building's walls and ceiling have 8" of glass insulation + 1" of rigid foam.

Because I did not remember the tubing, I also did not remember the (important) foam insulation mentioned several times. In my large shop, it turns out that the floor is a big heat sink, thermally connected to the gravel & bed-rock below. During winter I put a thermometer against the slab with insulation above it and found that during the entrire winter, the slab never went below 45 degrees. What this means is that I have a heat sink that keeps thing from getting too cold. Even over a winter that I was out of state and did not do any heating at all other than solar gain, the air temperature never went below 35 degrees. In the summer, it also holds down temperatures.

I have been quite happy using a propane forced-air shop heater (150K BTU/hr.) and a single large throught-the-wall A/C (25K BTU/hr.). I heat or cool a few hours before I start working and am pretty comfortable most of the time with a modest cost. I added a large basement dehumidifier (run 24/7 in the summer) and a wood-stove recently. The dehumidifier allows me to keep humidities in the 50's no matter what it is outside. The wood-stove is not only economical, but gives me the ability to heat up faster and even make it 80 degrees if I should want to.

The main difference is that my heat/cooling is on demand, so I am not using energy when not working. I do miss the warm feet effect, but I have some rubber pads in critical places in front of machine tools and work benches. (I could even get some electric socks!)

My question for you guys with radiant floor heat is do you leave the unit on (with its thermostat, of course) for the whole winter, or do you shut down (or dial down) if you are not working for a week or more?

P.S.: I would recommend considering solar effects if you have sunny days in winter as I usually do. Between my south-facing gable and four sky-lights, I have almost sq.ft. of polycarbonate two-layer glazing. Not only does this reduce the need for using electicity for light, but it really helps cut down on fuel costs in winter. By 10 AM on sunny winter days my attic is above 60 degrees and a thermostatic fan pumps the hot air through the insulated ceiling into the shop. The cost of the fan electricity is very little. In the sumer, I just ventilate the attic so heat does not build up enough that the ceiling feels warm, even when it is in the 90's outside. Even the heat gain at my translucent 12x12 door is minimal in summer because the sun is at a high angle, while in winter the sun's low angle sends heat and light deep into the shop.

 

Mainly, heated slabs radiate outward rather than downward, so insulation on the edges of the slab is most important. The slab will be about 75 degrees F. Any cooler surface in contact with the slab will try to steal its heat. If you're pouring up against your foundation walls, insulate between the slab and the walls.

 

Although we are only a handful of hundreds of miles apart, our weather is quite different. In summer, we may never reach 90, if we do it only lasts a few days to a week.

In winter we may be sub-freezing for months and have been sub-zero for over a week. (I know that doesn't sound like much to da Minnesotaeans.)

And the recommedations I've seen is to choose the heat level you want and just keep the fire fueled.

As for solar radiant heat in winter, the sun is so low in the dead of winter, we don't get much of that and with 6" or more insulation or, as in the case of the house with double-pane, inert gas filled windows with UV shield, etc., we don't gain much heat there anymore (but we don't lose much either!).

I have heard of folks who collect heat via collectors, store it in underground tanks (using water to transport & hold heat), then circulating either through the floor or a heat-pump affair. Something like that supposedly works well in areas like yours because it can be used to cool as well. I don't know, personally.

Also, I don't know how the contractors are in your area, but I have spoken with a few here and the majority want nothing to do with "constructing" anything having to do with the heating side of the project. It's almost like it is too much to ask of them to earn their money. And they don't want to step on the other trades' specialty.

So try to find a plumber/heating contractor who will pour and finish your basement or garage floor.

There's a lot of work out there for someone if they wanted to fill that gap and be adaptable.

 

I leave my thermostat at 45 degrees all winter long and the garage stays comfortable. I work in a light coat, and since you're doing manual labor, you stay very comfortable. I have 2 ceiling fans for when it gets hot, but they're not needed when the heat is being used because the floor is the heat source. It's cheaper to leave the heat on all of the time, than it is to turn it off and on.

 

wiseguy,

It looks like we are neighbors. How much propane do you use in a winter? I have averaged around 300 gallons lately, but would expect to use the whole 400 gallons my tank holds over a severe winter.

I think your system is good for a situation where you work almost every day - I often do, but I can take a week off, using no propane, and still be upto 45-50 in a few hours. (I still do not have warm feet, though.)

 

I go through about 10 gallons a week. Right now I'm using a 100 gallon tank because I was unsure when I built it how much I would use. I think I'm going to wind up getting a 500 gallon tank and burying it next to the garage. That way I can fill it up in August or July, and I should be able to avoid any mid-season price hikes since that should last me all season.

 

Just for a side-by-side comparison, my shop is 56'x56'x16' and has 7.5" of fiberglass + 1" of rigid foam in both walls & ceiling. I ran the numbers and you have 5,376 sq.ft. of walls + ceiling and I have 6,720. Assuming you are also on the east side of the "mountains", our opposite approaches (I heat air & you heat concrete) seem to be in the same "ballpark" for amount of propane used. I still wish I had gone with radiant heat, but mostly for the warm feet effect. I think my uninsulated slab helps me keep cooler in the summer, but I would have to give that up part of that effect if I had gone with radiant. How many BTU/hr is your boiler?

MuddyAxles is right - the concrete guys really do not enjoy having to bother with installation of one more major system in the slab. What I would have done if I could go back, is to contract with the concrete contractor to get his gravel & steel in place and then hold off pouring while I installed the tubing (or had another contractor do it); then do the pour and finishing. I wanted a very slight slope toward my door so I could hose out the floor without all the water running toward the far corners. The same contractor who said: "We can do anythng you want!" at the beginning, said "We cannot do that!" This was a high-quality contractor, but they all seem to have strong ideas on what they will & will not do.