: Just another thought...for glassing, what if you didn't build the
: "room" you described but instead just hung a few of
: those IR heat lamp bulbs they have in hotel bathrooms and
: buffets? Potential issues might be they are not diffuse enough,
: and how would you keep them from overheating the surface?

: Just throwing it out there...

Those heat lamps are simply high-wattage bulbs running below their designed voltage. They don't get hot enough to glow white, but they do glow orange. That still kicks out a lot of heat (wattage) in the red and infrared area.
The price on them is much higher than on a regular incandescent bulb. And they wouldn't be any better for our needs.

There are also ceramic heat coils which are made of nichrome wire wound on a ceramic cone. Poultry farmers use these
to keep new-born chicks warm. Same idea, high wattage but just glowing. They are sometimes called "brood heaters". I suspect that providing a lot of bright light with the the heat might disturb the hatchlings.

On the non-electric side there are LP and natural-gas fired infrared heaters. Again, they produce a lot of radiant heat rather than hot air.

On the other extreme would be halogen lamps: they give a lot of light along with very directional radiant heating. Usually they cost more than standard incandescent lamps, but there are some great sales at Harbor Freight, for example, which bring the price way down. You need a floodlight which can handle the heat, but those are frequently on sale, too. Typically, these are in the 300 watt or 500 watt category. A pair of those hung overhead can provide light and heat to your workarea. But if you leave them on all the time to provide heat, your electric bill will skyrocket. If you keep cycling them on and off they'll wear out rapidly, unless you have some way to give them a "soft start" by applying a low voltage and slowly raising it to avoid shocking the filament.

Aim a halogen floodlight through a clear tent and the boat inside will get hotter that the tent material. Of course you ned to keep the tent far enough away from that lamp.

In a drafty environment you would get drafts and convection currents moving hot air up and away from an untented worktable. While the worksurfaces would be well heated by the radiant heat from your lights. As the hot air rises, the cold air moving in will cool off your work a bit faster than if there were no drafts. Heat which is lost is still paid for. Putting a tent over the work, and the heating lights under it, traps a pocket of heated air over the top of your work, and as that cools, it flows down the sides of the tent, pools at the bottom, or flows out under the bottom edge of the tent, warming the air near the floor. this warm air is then reheated by the bulbs, and circulates again. You are not constantly heating the coldest air in the room. You can use lower wattage bulbs and save energy dollars.

As to getting the area too hot? Heck, you already have the enviable solution there. Position the thermostat sensor from your controller and it will turn off the heat before things get too hot.

You might want to try and find a steady-state situation where you have just enough lightbulbs to keep the temperature at nearly what you want when they are on constantly. (maybe 3 or 4 60-watt bulbs) Then you just use the controller to operate another 200 to 300 watts for an occasional added burst of heat.

If your garage is drafty, you can always build a smaller "room" inside it, and heat just that area. You can make the room walls from cheap plastic stapled to frames of 1x2s, or use 4x8 panels of expanded styrene insulation held together with a few dabs of construction adhesive. What's your budget allow? Repurposed cardboard boxes make a cheap wall material, and gypsum drywall panels are cheaper than the insulating foam, but heavier.

Of course it might be faster and cheaper to track down the leaks in the garage and seal them. I think you can still get a rebate from the government for about 25% to 30% of your insulation costs. The leaks at the bottom of the overhead door are sealed with a rubber gasket, or a strip of carpet stapled to the inside of the door, or a "door snake" fabric tube stuffed with socks that have lost their mates, or in dozens of other ways. Once you get the space sealed so it can be heated economically, heat it. Run a hot-air duct from your furnace, install a space heater, or maybe get a wood-burning stove and feed that with trimmings from the neighborhood trees. We get our firewood for practically free by just asking the local tree trimmers. They don't want to haul it to the dump, so we give 'em a few bucks to drop a load on our driveway instead, and everybody is happy.

Get a mug of hot chocolate, curl up in a soft chair and spend the rest of the winter thinking about it. :)

Good luck on your project.

PGJ