shop heat--radiant floor

Oh, ana 'nuther thing, radiant will have difficlty in drafty barn like areas, insulation is waaaaaaaaay cheaper than oil or gas. If you expect to throw a pole barn with a tin overhead 14 ft tall and a coupla splotches a fiberglass to sooth your concience, it won't work[not saying you did that Karl]

I dont' know about Karl, but I have my thermostat set to 40F. Sounds really cold, but I typically work out in my shop in a long sleeve shirt quite comfortably. With the warm floor, your feet don't get cold. This is a big factor.

I am using an electric water heater on off-peak power (~$0.03/kwh). My heating bill is only an extra $50 or so a month.

I am heating a 40x48 shop w/ 16' sidewalls. I insulated the heck out of it. There is nearly 18" of cellulose in the ceiling. The walls are ICF. An effective R factor of 50.

I have considered adding a corn boiler for a primary system, but am having a hard time justifying given the above stated results to date.

"Karl Townsend" wrote in message news:z9aQd.312$ snipped-for-privacy@newsread1.news.pas.earthlink.net...

If you use the shop occasionally it probably would be best to use a thermometer to sense floor temp, set it lower than needed to heat the space at a comfortable temp. Then add a fan/coil hydronic heater that uses the boilers water to heat up the space when you want to work in there. You can probably run the floor at 70-80 degrees and still get the benefits of warm feet, and the fan/coil heater to boost the temps. Greg

For the slab, consider having the plant add fiberglass or PP chop to the mix. The chop acts like millions of pieces of tiny, distributed rebar, and with a 4000 PSI (six-sack) mix and good curing, you can forget about hairline cracks. The only downside is the finished surface is a bit "hairy" -- but for a shop floor that's OK as it's less slippery.

Big machines require a massive footer to minimize vibration. We have some 4500 pound machines sitting on a 4-6 inch slab, and the limiting factor for surface finish is vibration they create during heavy cuts. It would be better if they were on separate footings 12"-24" thick and isolated from the rest of the slab. I suspect stuff like hammers and such would benefit from the isolation too.

As for radiant heat > I'm in the design stage on a shop/garage and I'd like to put radiant tube in

Tim Killian wrote in news: snipped-for-privacy@bresnan.com:

I feel all you would really need is some metalized tape like the gas company uses when they bury lines, and a detector. As an added bonus, you could find the rebar in the floor also, so when you went to anchor a machine, you didn't ruin a concrete bit.

Yep, using it for part time heating isn't a good idea, especially with thicker concrete. Look at it like it's a flywheel that you spin up. Once it's to temperature, it's not a big deal to keep it there, but if you allow it to cool off, it's starting over each time, so it doesn't do you much good. My floor is an honest 6¼" thick, and has hoses @ 18" centers (as per Heatway's design) and keeps the shop very warm with no effort. However, in order to bring up the more than 40 yards of concrete to a temperature that keeps the shop warm takes hours. I fully intend to keep the heat on full time in my shop, even after I'm living in our new house, but I'll lower the thermostat so it keeps the shop at a more comfortable temperature for working. Costs a little to keep it warm, but to me it's worth it. I hated my old shop that had a cold concrete floor.

Harold

All you need do is go over the surface with a propane weed burner and the "hairy" stuff is gone instantly. I cast window sills from glass reinforced colored concrete and did as I suggest. Works great and takes almost no time.

Harold

My problem isn't the speed with which I can heat the air, it's the speed with which I can heat up the 4500-odd pounds of steel in my machinery.

It's pretty counter-productive to bring the air up to, say, 65F, then start breathing in a closed space with 30-degree machines. Pretty soon, they're coated with condensation, and the rust starts.

Better to well-insulate your space, and keep the temp up to the non-condensing point for your equipment and humidity level.

LLoyd

And for you folks who have radiant systems, did you take a look at heating the water with solar collectors?

I'm in NC so the heating load isn't massive and it's an option under consideration.

Thanks. Steve.

Yes, but the "hairy" surface goes away after a few weeks of normal sweeping. It's fine with bare feet, even (different part of the basement, but same mix).

Dave Hinz

Yup.

This would serve to bring up the air temp inside the shop much, much more quickly.

Another related idea is to lay the tubes out in squares instead of laying out loops that go all the way across the shop. if you use the square grid approach you will be able to heat just one section of the shop, as needed. I have a 12 foot square loop just under my turning center to protect it from dew.

FYI I am in the radiant business (radiantheat.COM) and I manufacture radiant heat manifolds in my radiant heated shop.