wood heat redux
Mar. 17th, 2006 02:12 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
chelidonSo we've just about finished the first full winter season of heating the main house entirely with wood. The wood boiler, a Tarm MB Solo 75Mk II along with a 957-gallon insulated heat storage tank, saved us burning many hundreds of gallons of heating oil over the winter, and kept the house nice and toasty with no problem. On the coldest days, we fired it daily, for 3-8 hours. On warmer days (40 or higher in the days), we could go 2 days or more without starting a fire, running off the tank. As it gets into Spring and Summer, we should be able to fire up the boiler less and less frequently, to perhaps once a week or so. We went through 6 cords of wood October-March, with the 7th cord we're burning now to last us probably through the end of the month. That's a bit more than I'd hoped for, and it was a warmer than normal winter, but I learned just this past month that cleaning out the heat exchanger more frequently than I'd been doing increased efficiency markedly, so I could probably have cut at least a cord off the total right there.
I have to say, the labor involved in going to wood heat is signifcantly more work than just having the oil company come by and fill the tank when it gets low, with an automatic boiler to fire up whenever it's needed. And...for the most part, I quite enjoyed the extra work. Hauling around 7 cords of wood has put me in better shape than I've been since my teens, and I find that I really enjoy building and tending the fires that keep us warm. It puts me much more viscerally in touch with the flow of life and energy that it takes to keep us warm, it's very literally hands-on, and I really like that. I used the ash I cleaned out of the furnace to put on icy patches on our road (instead of sand or salt) -- it costs me nothing, and uses stuff I'd just have to get rid of anyway. I'll use the remainder of the ash now that most of the ice is gone to add nutrients and change pH of soil when necessary, and sometime this summer, I want to experiment with making soap the "old fashioned way" (insert scene from Fight Club here), making lye from wood ash.
The thing that bugged me most about the wood furnace was getting the plumbers I had come help with the installation to do their job right. They installed a weighted check valve backwards (against my advice) and I had to bypass it to get heat back out of the tank (exactly what I was afraid was going to happen, but I let them argue me out of it -- they're the experts, right?) Grrr. And there was a bad (leaky) sweat joint and several dripping junctions, and it took them three months to get back in here and fix those things and install a bypass valve to manually shunt heat to a "dump zone" (i.e., cool the boiler down if the power goes out). And...*sigh*, the one thing that doesn't work right yet is that power-out valve. We had a chance to test it out this past week, when we lost power for a couple of hours one evening. I waited to fire up the backup generator until I could see if the power-out system worked, as I'd just gotten the boiler up to full temp (190 degrees), and I wanted to see what would happen. Sure enough, when the power went out, the valve to the "dump zone" opened as intended, but natural convection just wasn't enough to dump enough heat from the boiler, and the temperature would have risen to dangerous levels if I hadn't damped back the fire, and then fired up the generator to get the circulator pumps going again. Since one of the goals I had for this system was to run without electricity if necessary, I need to figure something out there -- either a separate loop in the basement to a big ol' radiator that's fine being only gravity-fed, or a backup battery system that'll keep a emergency circulator going long enough to cool off the boiler. Once I get the microhydro system in the stream, I'm less concerned, since I plan to set it up to go to our own generated power whenever the grid drops out, but that's at least a year or two out, given the amount of trenching I need to do with the backhoe to get it set up so that it won't freeze up mid-winter, which is, of course, exactly when the boiler will be most used.
Anyway, all in all, a very successful experiment, all things considered. I would definitely do it again, with pretty much exactly the same setup. But I'd get different plumbers ;>
I have to say, the labor involved in going to wood heat is signifcantly more work than just having the oil company come by and fill the tank when it gets low, with an automatic boiler to fire up whenever it's needed. And...for the most part, I quite enjoyed the extra work. Hauling around 7 cords of wood has put me in better shape than I've been since my teens, and I find that I really enjoy building and tending the fires that keep us warm. It puts me much more viscerally in touch with the flow of life and energy that it takes to keep us warm, it's very literally hands-on, and I really like that. I used the ash I cleaned out of the furnace to put on icy patches on our road (instead of sand or salt) -- it costs me nothing, and uses stuff I'd just have to get rid of anyway. I'll use the remainder of the ash now that most of the ice is gone to add nutrients and change pH of soil when necessary, and sometime this summer, I want to experiment with making soap the "old fashioned way" (insert scene from Fight Club here), making lye from wood ash.
The thing that bugged me most about the wood furnace was getting the plumbers I had come help with the installation to do their job right. They installed a weighted check valve backwards (against my advice) and I had to bypass it to get heat back out of the tank (exactly what I was afraid was going to happen, but I let them argue me out of it -- they're the experts, right?) Grrr. And there was a bad (leaky) sweat joint and several dripping junctions, and it took them three months to get back in here and fix those things and install a bypass valve to manually shunt heat to a "dump zone" (i.e., cool the boiler down if the power goes out). And...*sigh*, the one thing that doesn't work right yet is that power-out valve. We had a chance to test it out this past week, when we lost power for a couple of hours one evening. I waited to fire up the backup generator until I could see if the power-out system worked, as I'd just gotten the boiler up to full temp (190 degrees), and I wanted to see what would happen. Sure enough, when the power went out, the valve to the "dump zone" opened as intended, but natural convection just wasn't enough to dump enough heat from the boiler, and the temperature would have risen to dangerous levels if I hadn't damped back the fire, and then fired up the generator to get the circulator pumps going again. Since one of the goals I had for this system was to run without electricity if necessary, I need to figure something out there -- either a separate loop in the basement to a big ol' radiator that's fine being only gravity-fed, or a backup battery system that'll keep a emergency circulator going long enough to cool off the boiler. Once I get the microhydro system in the stream, I'm less concerned, since I plan to set it up to go to our own generated power whenever the grid drops out, but that's at least a year or two out, given the amount of trenching I need to do with the backhoe to get it set up so that it won't freeze up mid-winter, which is, of course, exactly when the boiler will be most used.
Anyway, all in all, a very successful experiment, all things considered. I would definitely do it again, with pretty much exactly the same setup. But I'd get different plumbers ;>
