Heating a woodworking shop?

Sure can be (remember the formula: heat+oxygen+fuel=combustion)

Depends (and this applies to #4 as well)on the system you buy. If I'm not mistaken, the new gas fired furnaces are essentially "closed" systems, i.e. they draw their combustion air from outside and then vent the exhaust outside. If you're firing a boiler vs. forced air, your problem in #1 is non-existent but I would still worry about dust build up on the unit. If I were doing this I would certainly create a utility closet to house the boiler - especially since you're dealing with new construction.

More even heat that's "just there" no dust blowing around when you're trying to finish a piece. FA might be nice if you were going to install AC as well but, what the heck, I have a 9600 BTU unit I mounted through the wall that chills my 24X13 shop down very quickly. You could do the same if you install radiant heat.

With a modern furnace you're pretty much assured of that, I think. The problem arises with forced air heat where you're drawing in the dust and distributing it via the system. Think of a big fan blowing over your shoulder as you sand down a piece.

If the slab has not been poured yet, the answer is _always_ yes, IMHO, at least for the tubing itself that goes in the slab. Once it becomes a retrofit job, the answer is often no. Put a separate loop under the area you are not heating at this time, and it will be easy to hook it up if you ever change your mind about that... In the meantime, put a thermal break between the two parts of the slab (heated now and not heated now) or you'll waste a bunch of heat out in the "unheated area" by conduction through the slab.

It's easy to do yourself with or without a helpful cousin.

Yes. A separately enclosed boiler room with it's own outside entrance is a nice solution to this, or a "sealed burner" combustion system with it's own outside air supply. Dust explosions suck, even if they are generally rare in woodworking shops, so some people feel they are no concern at all. Solvent fires also suck.

That very much depends. Radiant is not really much more economical for the same temperature in the shop (if you insulated the same for it as for other types of heat), but it may (due to qualities like having a nice warm slab rather than a nasty cold one) make you comfortable at a lower thermostat setting, which would save a bit. If you do a bad job insulating the slab, you might burn more heat on radiant - so do a good job insulating the slab.

If you use the shop regularly, radiant slab is a good setup. If you use it once a week, it's less of a good deal, since it heats up slowly, and cools slowly. A system which heats the air rather than the slab can heat up and cool down more quickly. Some folks set up both, so the radiant system keeps he shop at at least 45 F, and the other system can quickly bring the shop to 60 or 70 for short work periods, or the radiant can be turned up for longer periods of work. Others just learn to think ahead - if you always use the shop on the weekend, a programmable thermostat can be set to turn the heat up and down so it's always comfortable on the weekend.

Not having lots of air currents as with a hot air furnace or even baseboard hot water is a good thing in a woodshop because it keeps the random dust relocation down - helpful for finishing, for instance. Also, the heat delivery takes up no space in the shop itself, and the equipment is kept warm (and does not get covered with condensate) by contact with the floor. You also have much less in the way of warm and cold spots.

If you are so inclined, radiant also works well with solar heat to supplement the fueled heat, since the temperature of the fluid in the slab is not so high.

If you're considering under floor heating for a workshop, be very, very (did I say very?) careful should you decide in the future to drill any holes in the floor for mounting bolts for heavy machinery :) Failure to do so may well result in a few swear words being uttered!

The big problem with in-slap heat is that if you ever break a pipe you have to rip up the slab. Friend of mine lives in a house that her father (an architect--see for example Hatcher Square in Savannah) designed that had in-floor heat. Managed to break a pipe and it turned out to be cheaper to put in warm-air than to fix the in-floor.

Not sure that is as much of a concern as it was fifty years ago when copper tubing was used exclusively.

My parents built a home with radiant heat in the floor (concrete slab) provided by a network of copper tubing. Built it in 1952, sold it 1958, heard that it started leaking in 1961 and the new owners wound up converting to forced air (not a bad idea since they could also have central air). Not sure what caused the failure, seems to me it was some sort of reaction between the copper and the concrete rather than a literal breakage of the lines.

Current practice is some form of plastic/nylon/last forever material so other than physical trauma you should be okay. Just watch what you mount to the floor and how you mount it as Alun wrote.

First, as others have mentioned, are you going to heat it all the time? If so, insulate and go with floor heat. Insulate, because the heat flows by conduction better than by convection - into the slab and what's contacting the slab rather than up in the air to you. If you're going to up the heat to use, and maintain low otherwise, forced air. Heats you, and you insulate your feet. You see, the first couple of hours will go into raising the slab temperature.

There's also another method out there which runs the tubes above the insulated slab but below the flooring. Saw it on TOH. Might be better.

What they usually do here in Europe is to first lay the concrete floor as per normal. Then a layer of insulating material is laid on top of that, and then special plastic tiles with pegs that stick upwards, through which plastic pipes are threaded in a zig-zag fashion. Then a screed layer is laid on top of that. If localized repairs are necessary, it's a *relatively* easy matter to chip out the affected area, at least easier than if it's concrete. Such a construction might not be suited to a workshop though because the screed layer would probably be too soft.

Yes. Ask your local FD.

Electric heating is expensive.

Venting to the shop from combustion heating presents some safety concerns. Electrical heating doesn't need venting but is also $$$.

Radiant floor heat is usually gas/ or oil/hot water, not electric.

Insulate under the floor... worst mistake I ever made.

Ted, I built a workshop in my 45 x 54 pole building that is 45 x 12, almost the same square footage as you are planning. I used 2 x 6 studs and ceiling rafters and 6 inch fiberglass insulation and used expanding foam in all the joints. My heat source is a small electric furnace, $1100 installed, that has worked out very well although I do have the some dust circulation but it's not a big problem (I also installed a dust collection system) and I buy furnace filters by the case. I set the thermostat on 50 when I leave and it takes about 10 - 15 minutes to bring the temp up 70 the next morning. My cost in Jan and Feb are about $1.50/day here in Kentucky (we have some zero days here). I'm sure your's will be more in Michigan.

I think the key is insulation and a tight space. I did not insulate the floor. I also like the flame free enviroment.

If you would like more info as to brand name, btu output let me know.

LB

Ted, I have a 24 x36 pole barn here in Oregon. I use one of the small electric oil radiators to keep it warm. On 32 degree days it stays at about 60. If I have the dust collector running for half of the day (it is amazing how big the pile of unsanded bowls can get) it gets up to a balmy 70 by the end of the day. The amount of electricity used is minimal. robo hippy

Common practice is to plan your shop first, so you can lay the piping around any eventual holes drilled in the slab.

That hasn't been a problem for 20 years. In-slab heating uses a special plastic tubing with an oxygen barrier. You will also want to get the matching manifold to balance the system as well as the circulating pump. Any plumbing supply house that caters to contractors can set you up with what you need. Although there are dedicated boilers for these systems, most people use a hot water heater that have inlet and outlet ports just for heating. Get one of the 96% efficient units. Not only will you save money, but the flame is contained within a combustion chamber and dust/fumes in the shop can't reach it. Air for the flame is brought in with a pipe and fumes are discharged by one, too. Both are plastic and usually co-axial.

While an open flame could be a hazard, it is highly unlikely your shop will ever get dusty enough or filled with enough combustion vapor to explode, unless you use a lot of lacquer based adhesives and finishes. What WILL happen is that hydrocarbon vapor, from varnishes, paints, and OMS, will cause the combustion chamber in an open flame furnace or water heater to corrode and fail.

Dan

My husband built a woodworking shop here in northern Minnesota (near the Canadian border -- so it gets below zero for days at a time) and has radiant heat in the concrete floor with the hot water tubes and an electric furnace. He and his friends who work in there think it's the best thing they've done -- even heat and no dust flying. He has a new furnace with a lot of bricks to hold the heat and it can keep the shop warm for many hours even when the off-peak electricity is shut off periodically when it gets very cold.

never heard of that before i have seen the process done before and the nice thing about radiant heat is some times concrete contractors can regulate the cooling of the concrete by pumping water thru it ,if concrete cures too quickly or too slowly it will not set properly by having unevenes or worse cracks form and also the thickness matters too ,a couple garages i was in had a nice packed in base for the concrete ,and once the concrete had set even if the line cracked (considering the regular stuff you can jump on it all day and not crack it) there is a couple companys that will come out and pump a special sealant under presssure thru the line to seal all the little leaks that since , but it sounds like your friend got screwed on his radiant heat if they used metal lines they never will last and the concrete they used in a house on the floors are usually no more than an inch or 2 thick ,unless you meant in the basement then someone really screwed up the installation on it really bad .my guess will be that your friend used his hot water system for heating the floor which is a big no no in radiant floor heating becuase there is no antifreeze in it at all to keep it from freezing he should've had a seperate heating system for the radiant floor heating cause the actual heater is only about 2 gallons plus what is in the floor system itself ,if he used his hot water heater to do it thats just waiting for something to go wrong.

A few years ago a friend of mine had gotten ahold of some plastic fibrous material he had gotten from his one buddy thats in construction,it had a very high therme rating and he said at the time it was very expensive but very high r rating about three times or more than fiberglass ,but he said he could heat the new room with a candle and it was a big room with very high cathedral ceiling about 15-17 feet to it highest point and it was nice and toasty and he said his heating bill went down almost 20 percent . Wish i could remember what the stuff was called but it was as thin as external moisture barrier but it had a warning for indoor use only ,but just wanted to say is if you put your money into the right stuff and get the best insulation you can then the radiant floor heater is all youll really need and plus the radiant floor heater is easily adaptable to upgrades of heater units if you need to do so in the future to more efficient ones every ten -15 years.

So what _should_ Frank Lloyd Wright have used in the houses that he designed with in-floor radiant heat? The new plastics might be OK or might not. Look kind of thin to me. Maybe you _can_ jump on them. So what? Being jumped on is not the usual cause of failure. And how much of the flow does the sealant obstruct and how much does it reduce thermal efficiency?

Still has to be ripped up to fix the leak.

They don't have basements in Georgia. At least not to speak of.

There was only one heating system in the house, and that was the radiant floor. And I seriously doubt that any professional architect would use a water heater rather than a proper furnace to provide heat for a house that he intended to live in.

If it is your contention that in floor radiant heat is so reliable that fixing it should not be even a consideration, then quite frankly, you're a damned fool. Anything with moving parts can fail, and anything that water flows through is eventually going to leak.