Marc, After you're done burning, use a flat edged shovel to remove the thin layer of ash. I planted a pear on a similar site, though 5 years+ after burn, and it was the only pear that died out. It began drying out on top in the fall, began sprouting in February from the rootstock, I attempted to graft onto rootstock in late march, but cambium was dry-dead. There are some benefits to using ash, but from what I've read it's best to apply sparsely as the lye in it is caustic and will burn. I don't know what else could have been in the burnpile. Gypsum boards...

I heat with wood. I was given a wood stove from a house. It has an air jacket and a blower attached to the back. I built a separate metal shed about 15 feet from the end of my 14x48 high tunnel. I put it on the end that is downwind, at least most of the time. I used 6" insulated ducting to go back and forth from the stove to the high tunnel end. I recirculate the same air, so there are two pieces of the ducting. Even with a raging fire and venting in air that is too hot to hold my hand against, I only get about 15 degrees of temperature boost from the outside air. The r-value of poly stinks; there's just no way around that. There's no way I could have made the stove work inside the high tunnel itself; it's too big and too hot, plus it leaks smoke. A smaller stove might have fit inside, but the smaller the stove, the more often you have to refill it with wood. It really is a better design to have the stove be external. Firewood is messy, full of bugs, and having the stove outside frees up valuable greenhouse space. Heating water with the stove, instead of air, is an even more efficient design, but I didn't have the money to set it up. I looked at a "hydro- coil" device, which is a tube that mounts inside the stove that you pump water through. They have plastic pex tubing now that is made to emulate the radiant properties of copper pipe. If you ran that over your asphalt, then poured the minimum 4" of concrete over it, that would be the best setup I could imagine.

Sure, Build.com and other sites sell them. Found one in about two minutes. Here But they are not going to work for a sloped ceiling. No one probably makes one that swivels like you would need for that application. Heat in a radiant form, as in a light bulb heater, travels in a straight line and you will be heating whatever surface the ceiling pitch has the bulb pointing at. You need to build out a triangular box to put the fixture in. You can drywall it so that it is not as obvious as mine was. It is not a great picture, but in the upper left side of the photo you can see the maple triangular box that gives my light fixture a level surface to hang on.

Prior to the introduction of the EPA and the Clean Air Act in 1972 it was customary for single family residential homes in the suburbs to have an empty 55gal barrel in the back yard. The barrel was stood on end, the top was cut out, and they punched about a dozen 2" or 3" holes around the bottom to let air in. The household trash was collected in paper grocery bags and once a day just before sunset they would take the trashbags out, drop them in the barrel and burn the trash. We were supposed to have a heavy screen to lay over the top of the barrel to prevent sparks from flying out, but most ppl ignored that. As you might imagine, there was always some trash that didn't burn, cans, vegetable peelings & such so about once ever month or six weeks we had to haul the barrel to the town dump and dump it out. In the larger cities and ppl of means in the suburbs had an indoor trash incinerator, which is what I think the unit in the first photo is. The trash incinerator was a simple burner that you dropped your trash bag in and as it burned it had a flue pipe connected to the house chimney to carry the smoke out. Some actually had a gas burner to effect a better combustion of the trash, but either way, you had to open the door on the bottom and shovel out the excess that didn't burn. Opearting a home trash incinerator is strictly prohibited today. The large dark unit in the second photo appears to be a coal fired furnace, athough without seeing the rest of the top I can not tell if that one is a steam or hydronic boiler. To start a coal fired boiler or furnace you began by opening the firebox door and building a small wood fire. Once the wood was burning good you put a little coal on it and waited till the coal was burning good before adding more. From a cold start it usually took about two hours of close attention until you had a full fire up. Once it was burning good you had to go down about once ever 3 to 4 hours and shake the grate (the pull handle on the left side) to break up any clinkers on the grates, then add a couple shovels of coal. At night you went down right before bedtime, shook the grates and added about 4 or 5 shovels of coal, then open the ash pit door on the bottom and get 3 or 4 shovels of ashes, which you carefully spread over top of the coal so the coal would only smolder overnight, and first thing in the morning, even before coffee, you had to go down and use a poker to break up the ash klinker on top and shovel some coal on to get the heat up again. On the ash pit door there should be a flat panel that is hinged from the top, which is called the draft door, and it was connected to a damper chain from a pulley above the furnace. On the first floor of the house there was a brass knob on the wall that was connected to that damper chain. If you wanted to turn the heat up you turned the knob and it would open draft door allowing more air into the firebox and heating the fire up, but careful, The chimeny flue had a barometric draft relief door that would normally regulate the amount of draft ofer the fire, but if you opened the draft door too much, the fire would get too hot and you ran a serious risk of a chimney fire. Growing up in the 50's & 60's it was a right of passage for boys about 10 years old to learn how to burn the trash and stoke the furnace. The smaller unit to the left of the furnace in the second picture is an oil fired hydronic boiler. If you look on the large copper pipe on the front of it you can see a black section that is the circulating pump for the hydronic system. In both of those boilers the water is contained inside cast iron sections and if the boilers were not properly drained it is almost a foregone conclusion that the water has froze and cracked the cast iron over the years of sitting idle. It also almost goes without say that over the years of storage the firebrick & refractory lining in the fireboxes has deteriorated beyond use by humidity. My greater concern is Asbestos. Both of those boilers will have to be dismantled in place before they can be taken out and they contain substantial amounts of asbestos. It will require complete containment by a professional Asbestos Abatement crew to dismantle and remove those boilers and that can be very expensive...did your realtor disclose that fact at the time of sale?