I'll have to check on the boiler's output for you. When I did my slab I put down the foam insulation and wire, and then installed the pex tubing. Installing the pex was very easy and didn't take much time at all. I installed a little over 2000 feet of 7/8" pex and it only took about one hour per roll. The concrete contractor came in and checked it out before pouring, gave it his blessing and then poured it.

 

I am sorry that I did not install the tubing when I could have. The only parts of my shop that I did not do myself were the excavation and concrete, and then the hanging of the 56-foot long trusses. I had hoped have one contractor to the excavation and concrete, but found that I had to split it up. This process got so complicated that my intentions of installing tubing got lost in the shuffle. My advice to anyone planning a shop with radiant heat is to remember that it cannot be an upgrade later on.

No hurry on the boiler output. I was just curious.

 

2" foam underneath(plastic below that for vapor barrier), on sides, and 4 feet outside of the perimeter underground(prevent frost). Pex laid in one day(2 guys), and the electric boiler is a "monitron". 2x6 construction with blown in insulation overhead. The size is 36x44 10' walls. 5"slab w/rebar, and 1' footer all the way around.

When they powered it up, it took a couple days to go from zero to 60 degrees. And another couple days to whick the moisture out of the concrete and walls. Like a sauna. They're still doing the sheetrocking, but it's like walking into a different world from outside, where it's been cold, windy, and snowy all week. My 2 cents.

 

One of the nice things about "tubing in the floor" radiant heat is that you have a huge heat sink that stabilizes everything in the shop, not only in the winter, but also in the summer, assuming that you do cooling through the same tubing.

I like my system, but I have to "listen" to my heater & A/C fans. This is a hobby shop and I enjoy the greater peace during the spring & fall.

 

I have in-floor heat on 2 zones in my garage -- the front 4-car garage stays at 45 all winter and the back 2 stalls stay at 65 all winter (workshop). Only negative I can relate is that, in MN, you'll have family and friends over all the time to come and do their work in your garage! Nothing like crawling under your truck in the dead of winter on a nice warm floor :-)

I have about 4,500 square feet of in-floor heat in all, and it runs off a 75 gallon water heater. Keeps up just fine.

 

The Munchkin Boiler I'm using puts out 80,000 BTUs. I bought it because of its efficiency and proven track record. A little pricey, but it's tough to beat its efficiency.

 

Guys, maybe I can give you a little different perspective as I am a heating contractor and do radiant floors for a living. I have seen many "DIY" installations with major problems. "Hey, it's just a matter of running hot water through a tube right?" There is actually a good amount of engineering that goes into a properly designed system and it often cost a lot more money in gas bills and repairs to do it wrong. My advice is to talk to a Pro and get a heat loss calc. Then he will determine the proper tube spacing, tube length, design water temp, reset curve, pump sizing and boiler sizing. Notice I said boiler and not water heater. A typical gas or propane water heater is in the 60% efficiency range, where as a good modulating/condensing boiler (like the Munchkin and others) should be in the upper 90% range. As was mentioned, slab insulation is a must. If the slab edge is not insulated you might as well heat the building by burning dollar bills. Just remember, you get one chance with the tubing and once it's in the concrete it's there forever. Beware of the internet companies that will sell you a "One size fits all" system. Check out Heatinghelp.com and click on "The Wall" for a lot of great info. These guys know there stuff and will answer your questions. By the way, I am not affiliated with that site at all.

 

Thanks NS -- I figured that about the water heater but it was all I could fit into the budget at the time. You've helped me make up my mind about getting a proper boiler when this one goes out. Mine was professionally designed by my cousin, who does installations for Wirsbo (did fun stuff like Coors Field in Denver!). I'm all insulated and engineered, so the WH keeps up well -- only runs 5 or 10 minutes an hour on cold days.

 

[ If the slab edge is not insulated you might as well heat the building by burning dollar bills.

I unfortunately did not do this. I think I understand you as saying the foam should have come up between the wall and the floor? This seems obvious just ugly having pink or blue foam on the floor. Well I guess I better find that money tree and start cutting it up. Thanks.

 

If you have a slab on grade you can probably add insulation to the slab edge. Dig the grade back and get some foam board on there. Do you have a pole barn or regular stick bilt garage? With a pole barn you can add insulation pretty much the same way. As far as seeing the ugly foam board, the catch is by code (in Wisconsin anyway) it needs to covered with something to protect it from damage and the sun. There are products made to do this. Vinyl and brush on concrete type coatings come to mind. Basically any type of thermal break you can get between your warm slab and the cold ground is a good thing. You may notice that the snow is melting faster around the perimiter of you building than everwhere else and in extreme cases, I have heard of peoples flowers growing at the edge of the house in the middle of winter.

 

I wish I had put tubing in when I poured my pad. I waffled because I was in FL, but I think in hindsight that it would have been the cats **** if I had done it that way. Like its been mentioned, you don't have to do the boiler and pump right away.

 

NS F250 I have block walls sitting on footings. I assume you where talking about the inside of the building not the outside? Here's a pic.

By putting foam on the outside, helps, I understand, but the cold still gets absorbed into the wall.

 

Yeah, outside on the slab edge is what I meant, but I did not realize your garage is built into a hill. Ideally the outside of the block walls and footings would have 1 or 2 inch foam applied before you back filled. Is there foam under the slab? Or is the slab even poured? Can't really tell from your pic.

 

Oh ya everything is finished on the inside. I used foil backed bubblewrap under the slab. I guess I should dig around the building and stick some foam in there.

 

Im put low tech radiant system in 14 years ago. 24 x 24 shop uses gas hotwater heater. Warm as toast. Great for drying wet gloves boots and tow straps.
I did not use any side or bottom insulation. In snow season I see no snow melting at edges. As for bottom insulation, bad idea. The earth is a giant heat sink and stores any heat that migrate down. The Radiantech guy told me " It's your heat and you paid for it. It will always be there." In the event of a complete system failure it would take months to freeze the water in the pipes.