Well, I just googled "heat transfer" and "soil". The first page I find is: http://www.wtamu.edu/~crobinson/SoilTemp/index.html "Conduction is the primary mode of heat transfer in soil." Do you have a better link? Conduction was what I assumed was the primary heat transfer method when I wrote my simulator, so if it's not, I'll need to modify my simulator a bit. As for heat balance. Let's assume that the PVC's diameter is 0.1 meters. That's a circumference of ~0.31 meters. Times 50, that's 15.7 square meters. Assume a metric R-value of 0.2 (American R=1.14). Conduction is (Temp1 - Temp2) * Area / Insul_R, so Delta-T * 78.5W. 10 degrees average temperature difference will unload 785W into the soil. I would anticipate, as well, that with soil's low R-value, heat will flow much faster through the soil than from the PVC to the soil, thus equalizing temperatures (I'd have to write a simulator to check this out). My heat balance simulator shows, for such a greenhouse (simply adjusting my greenhouse to be the proper length and width; your geometry will be important), a peak input heat of 1458W added to the air. This happens early in the day, when the sun is bright but the greenhouse is still quite cold. By high noon, it's down to 1237W, and by 3:00 PM, it's actually cooling because of the less optimal sun angle. I can get you a breakdown of the calculated heat inputs and outputs if you'd like. By these numbers, at peak heating time, the PVC will be sapping half of the greenhouse's incoming energy. At non-peak heating times, it will be reducing the heat input even more. Again, I could do a more detailed simulation if you thought it necessary, but a rough look at it appears that this system would do a very good job at heat storage. As for heat capacity (the other issue), my research indicates that soil specific heat ranges from 800 to 1500 (lets say 1100) J/kg*K, and soil density is typically around 2000 kg/m^3 (although highly organic soil can be much less). Assuming a pipe depth of 0.5 meters, we're looking at 6 cubic meters of soil. This translates to 12,000kg of soil, storing 13.2 MJ of energy per degree, I.e., 3.6kWh/degree, meaning that the soil would only change less than 1 1/2 degrees in 6 hours. Now, this a very rough calculation for a number of reasons. It assumes even soil heating, which is false (this works against soil energy storage). However, it also assumes that no soil will be heated below the pipes, which is also false (this works in favor of soil energy storage). Assuming that the factors roughly cancel out, the soil temperature should fluctuate very little between day and night. I already know, by my pipeless-greenhouse simulation, that this indeed is the case. About 1 foot down, I show the temperature shifting only about one degree between day and night. Of course, since you have some complaints about the conduction-dominated soil heat transfer model, I'm open to changes in this. As for water usage, the areas downriver from us are rainer than we are (east Texas, Louisiana, etc). The US's water problems are mostly in the rockies and especially the desert southwest. Phoenix is subsiding from the overtapping of its resevoir. LA has basically terraformed the Owens Valley by the amount of water it's diverted. Etc. However, we have little to no effect on them out here. As I stated, the world doesn't have a water shortage; rather, there are regional water shortages. Conserving water in an area that doesn't have a water problem doesn't help with water problems in areas that do. As for mold, that's certainly an issue to consider; however, I'm not concerned. Sealed PVC will only have the moisture from your greenhouse affecting it. As mold doesn't grow very quickly on the walls of a PVC greenhouse, I see no reason to expect quick mold growth in the underground PVC pipes. If mold does become a problem, with the "auger-slant" approach, what's the difficulty? All pipe segments come up to the surface, so you can clean them out, or even potentially replace them (if your soil is compact enough that the hole won't collapse) without any digging. As for water collection, the PVC will only be colder than the inside air during the daytime. At night, it will be hotter. As the PVC will have air actively blown past it, if there's any water in the system, the air should reach the saturation point with ease. If, by some accident, water accumulated, I could take a few joints off and blow each row out with a leaf blower (I doubt one could blow water out of the whole system at once, but a single row should be doable. If not, a half row, a third row, a quarter row, or whatnot). I'm not knocking you, only trying to get a reality cheque for the problem Oh, by all means, do! I'm actually enjoying this discussion. Some things I actually hadn't considered before, such as mold. Naturally, I'd start out with just a single row of PVC and see how it works out. And while I certainly don't see anything close to a showstopper here, who knows what the future will bring. By the way, your water system sounds nice -- making use of your heat-sink water as a fish pond. I'll have to consider that for the future. ;) All of my simulations show that the water tends to stay at a nice comfortable temperature even when if air temperature gets uncomfortable, so fish should be in good shape.

The best thing to do is call a professional to do this type of service. You wouldn't want to mess anything up with the wiring. I also would get the problem fixed before running the furnace much longer, because it could trip a limit switch if not enough air is passing over the hot heat exchanger. This isn't a 2-stage furnace, is it? How old is it?

Anyone know anything about Shaver 165 outdoor furnace. Do they work as advertised?

I know this is an old post but I felt I should chime in for any future readers. We purchased a house three years ago that was heated with an outdoor wood boiler. We live in rural Ontario, Canada where February is typically -35 Celcius. We had never heard or seen these things before but heating sources in the rural area are limited to wood, electric heat, or propane. Here's my experience with them after three years or using one every winter: The very first time you fire up the boiler each fall there will be lots of smoke for an hour or two (just like when you light a fire in your fireplace - there is lots of smoke out your chimney upon first start). After the boiler is at temperature, and you're burning seasoned wood, there will be VERY little smoke. IF the boiler is a gassifier (re-burns the gas before it exits the chimney) then there is practically NO visible smoke at all - EVER. Most boilers have thermostats that ONLY open the dampers and turn on the down draft fans when the water temperature goes below a set value (160 degrees usually). For my boiler, in the dead of the winter here in Canada (-35 degrees C), the boiler will turn on once every 45 minutes and stay on for 10 to 15 minutes to re-ignite the wood (this is the only time that smoke would ever come out the chimney if it wasn't a 'smokeless'/gassifier unit.), then close the dampers and the fire is put out, leaving only red hot wood embers/coals. You WILL, however, smell the wood... which most people think smells nice (think of a campfire on a cold night, or cuddling up to a fireplace with a hot chocolate). However, if you dont like the smell of a wood fire, then this will put you off. The pictures that others have posted above could be 1) People burning something that they're not supposed to be burning like garbage 2) burning green/wet wood - so you're seeing STEAM in those pictures 3) the first start up on the boiler (either of the year OR maybe they turned it off while they were away on vacation and re-fired it when they returned). As a home owner with a boiler for my heat source I can say that I envy those with natural gas. A boilers is a LOT of work, a LOT of maintenance, and takes a LOT of energy/time to cut, stack, and load the wood (not to mention the ash clean out every two days). BUT.. for us, its half the price of propane and 1/6 the price of electric heat.