Who has radiant floor heat in there workshop?

The first time each year when you fire up the heat, it will take an inordinate amount of energy to get the slab warm, so don't think your second energy bill will be like your first.

You say the location does not have gas, can't you put a 100 lb. propane bottle in? Better yet, a 500 gal tank? Or, like a lotta these guys do, rig a boiler that burns waste oil or wood, corn or Rosie O'Donnell reruns.

Best advice is Insulate First. Even gluing up 1" foam panels or just fiberglass batts makes a big difference.

Yes, Your contractor wants to place this slab in smaller sections because it's eaiser....That's okay, easy is good. Could be for a number of reasons....as far as pinning the slabs together, do you mean as in smooth steel dowels, say 16" X 1/2" dia? spced avery 2'? thats perfectably acceptable. This pinning controls the "lifting or sinking of the two adjecent pieces. As far as running your pipes through the cold/expansion or control joints, place your pex in a pvc sleeve. shove some styrafoam (injecting foam is best) into the annular space, just enough to keep the concrete from going inside the sleeve. The sleeve allows for any movement that might take place...and it will move. And don't be suprised if your concrete cracks either. Pex is great for concrete encasement! Very forgiving.

It's important that the slab sections are able to move on or around at least 1 side of the pinning dowles. Sometimes we place a "speedy sleeve" into the form work, (its a plastic sleeve that is left in the first pour. It's about 8-10" long and 3/4" dia. After the concrete sets up and the forms are removed, you can insert a smooth dowel into the speedy sleeve and place your next piece of concrete. OR, you can grease a smooth dowel, on one side. This is to allow the concrete NOT to adhere to the dowel. Thereby allowing the concrete to mooooove.
Watch these finishers!!!!! !!!! (ie shaved apes). You do NOT want your slab reinforcement on the BOTTOM of your finished slab! If you see this taking place, stop the pour!!! and make the crew PICK UP THE REBAR OR MESH. The reinforcement should be placed on "chairs" (plastic supprots) or Dobies" (square concrete blocks, preffably wired). Also, (yeah, I gots lots). the stiffer the concrete the stronger the finished product! Confer with your supplier and the contractor BEFORE you begin, When you place concrete, Hydration occurs. The chemical reaction evaporates the water in the mix, the more water you have, the more microscopic "voids" (where the water droplets were) you will be left with). Remember who is paying for all of this.....get waht YOU want and have paid for.

Now, EXAMPLE #1, Typical tract house in So. Calif.
I pulled up the carpet in the dining room and bathrooms to install tile. The floors were cracked MAJOR! these cracks were 5/8" wide! looked like a giant spider web. i could see dirt below the slab. This is called "shattered" caused by a LAZY crew who is un supervised. We'll just add 100 gals of water and the concrete will level itself!!! that's the mindset of 95% of the tradesmen I have run across! Concrete finishers are the worst! I know concrete is HARD work...I did it (the right and the wrong way) for 32 years...sl

AND watch these guys as they work arounf your pex, they'll tromp all over it. It should be pressurized with WATER. (can you say hydrostatic pressure). this will leak water (in the wet concrete slab) if it comprimised....okay, i'll stop...sl

A 30 x 70 slab can be poured all at once. Just be sure to place control joints in a way that you end up with sections of floor no greater than 1500 sqft. My main shop floor is 30 x 50 and I placed it all at one time with two control joints. Your probably looking at 3 control joints for your floor. Run your piping parallel to the control joint to minimize crossing the joint if your worried about it. You will have to cross the control joint at some point which is no big deal. Look in the pic and you will see where all of the supplies and returns pass under the CJ to get to the manifold. The CJ is that metal piece that looks like a steel stud. Have the sales rep from whatever company your buying your radiant supplies from do a heat loss calc and layout plan for you. They don't usually charge for this and you will get a drawing showing what size tubing you need, what spacing to install it at and a layout for each loop. You really want them to provide this for you so that each loop will be balanced so you end up with a nice even heat distribution and no cold spots. A radiant system is made up of multiple loops of similar length and not just one long run of tubing. Also as far as control joints go, use the cast in place ones with the tear away stiffner so you don't have to risk cutting through one of your lines when the slab guys cut the control joints. Make sure you go over this with your floor finishers before the show up on site so they are prepared.

In my upstairs we put down Warmboard which is an aluminum clad 1 1/4" subfloor with routed grooves for the PEX to lay in. I don't see why you couldn't use that stuff to make radiant walls. It heats up (and cools down) in about an hour so at night you drop the temps (again the programmable thermostat). Another nice thing about Warmboard is, if you do drill (or as I did) screw a hole in a tube, you can use a PEX union joint to fix it. Can't do that quite so easy if your tube is in a slab, needless to say.

And, yes, you can rely on it as the sole heat source. In fact, if you use a gas hot water tank (I have two 40 gals) or some other non-electric heat source, you can heat your building in a power failure easily since the pump that circulates the water through the floor doesn't need much power. A small gennie or solar/battery pack could do it, no prob.

Ours went in on a few real cold days, the guys got in a hurry and didn't put the specified amount of silicone in the routed groozes before laying the PEX in. Result: the tubing popped up on a few of the bends. For toilets, don't use wax rings (they'll melt), use PVC rings.

I put radiant heating in the slab of my new shop. Shop is still under construction so I can't tell you how well it works. If you decide to go this route be sure to insulate your foundation walls and the underside of the slab to avoid heat loss to the outside. You need to also be sure that you use oxygen barrier tubing in the system.If you don't you will end up with a sludge in the system that will reduce your heat output as well as shorten the life of your boiler. Originally I wasn't going to put it in, but family members who are plumbers, convinced me to at least put the tubing in in case I change my mind. Since then I've talked to others who have raidiant and they swear by it. I look forward to working in there in comfort on those cold winter days.

If you open a door and cold air rushes in, it immediately feels warm again when you close the door because it doesn't heat the air. Sit in a chair and the chair is already warm.

I'll never go back to forced air heat.

BTW, (I know some may be getting tired of me harping about this stuff) if you haven't done it already, look up solar air heaters. They're cheap and easy to build and provide free clean heat. While you're at it, go to Wikipedia.com and check out my article on Earth Cooling Tubes. I just installed them on my new home and will be reporting on their effectiveness in a few hot weeks.

Anybody else doing anything new to stay warm or cool without spending a fortune?

They are really nice on the feet in the winter, and if you have to lay on the floor. Evaporates water off the floor quick too even if you don't keep the shop really warm.