Since every heating solution is a house-specific problem, let me set the table. Our home is a 1958 vintage 3600 sq.ft. split-level house, cinder block construction, with a vaulted ceiling and no attic. The heating system installed in the home at construction was a baseboard hot water system run by an oil-fueled boiler. The boiler room is in the middle of the lower level and is quite small, just enough room for a boiler and plumbing.
I bought the home in 2005 from an elderly lady who had owned the home with her husband since 1960. The boiler had been replaced in the 1990's, but was functioning poorly due to a bad sludge accumulation in the underground oil tank behind the house. Boiler maintenance was a twice a winter requirement, and in the last year or so it had gotten so unworkable that even monthly maintenance failed to keep the boiler working efficiently. So, late in the winter of 2010-2011 I shut it down for good.
I had installed a high-efficiency wood stove in the lower level family room in the middle of the house prior to the winter of 2009-10, and run it as supplemental heat. For winter 2011-12, I attempted to run only with the wood stove and three electric ceramic room heaters. I burned about eight cords of firewood in 09-10, and six in the warmer winter of 11-12. However, I couldn't get sufficient heating circulation and the cost of the electric heaters made it obvious that I needed a better central heating solution.
New geothermal and forced-air heating solutions were infeasible because I had no where to run ductwork without making the house look like an industrial-themed restaurant. I investigated electrical "mini-splits" but the cost of a system for a house of that size was prohibitive. Since my return from Austria in 2008, I had been nursing a dream of running a wood or pellet boiler/solar thermal combination out of a garage conversion, but again, the cost of the installed system was out of my league. I also had the numbers run for a solar PV system installation, because the contractor had proposed that the economics of solar PV now approached the cost of a solar thermal system. The payback for solar PV on my house was 56 years without government incentives, and 40 years with them. Unfortunately, a 40-year payback on a 25-year system just doesn't make sense, and I didn't feel it gentlemanly to ask you all to help me pay for it, anyway.
So, after nearly a year of digging in all the wrong holes, I arrived at a simple conclusion: my best bet was to simply replace the old boiler with the best alternative new boiler I could get. The alternatives available were fairly straightforward; oil, natural gas, propane gas, coal, round wood, or wood pellet. My problem was to determine which fuel/boiler/installation best met the needs of my family. But each potential solution had at least one drawback.
First, I could have stayed with oil without even buying a new boiler. The old boiler still had about 5-10 years of serviceable life in it, but I would have to replace the oil tank so that clean oil could be fed into the boiler. The oil company gave me a bid to install a new above-ground oil tank in the back of my house, and they would simply cap off the old oil tank. So, my first scenario was
- Stick with the old boiler, hope for another ten years on it, install a new oil tank, and live with the high cost of heating oil.
The new tank would cost me $1,400, and I used $3.75 per gallon average over the next ten years as my baseline comparison cost. We had been averaging 1,200 gallons per winter since buying the home, and with the improved efficiency of the boiler due to the cleaner feed, and the addition of the supplemental heat of the wood stove, I figured we could reasonably lower our oil consumption to 1,000 gallons per winter. So, my total heating system cost over the next ten years would be $1,400 + ($3.75 * 1,000 * 10) for a total of $38,900, or $3,890 per year.
Next, I considered the "natural" alternative...wood. Since I really wanted a wood boiler, I researched several different types, and finally decided on one that I thought to be the best hi-efficiency unit that would fit in my small boiler room. (I won't discuss brands in this column, because, what worked or didn't in my case may not apply to yours, so no sense naming names.) Since I knew my Go Wood reputation was at stake, I came up with what I thought was a great woody alternative scenario:
2. Replace the oil boiler with a high-efficiency wood boiler.The wood boiler of my choice was a pretty high-tech wood gasification unit, and the system required a separate thermal storage (hot water) tank to maximize efficiency. The cost of the installed system was $7,945 for the boiler, $4,000 for the stainless steel tank, $3,000 for installation, for a total of $14,945 installed cost. Then I had to figure out the cost of the wood.
Now, the way most companies calculate fuel cost is on a dollar per million BTU basis, and then the home owner has to guess how many BTU's they're going to use. I had the advantage of knowing my historical baseline, and therefore simply needed to figure out a simple alternative fuel equivalency to a gallon of fuel oil.
For wood, that equivalency is fairly simple. A gallon of #2 fuel oil provides 115,000 Btu's at 83% boiler efficiency, which is what my old boiler was rated at. A cord of seasoned firewood delivers 15.4 million Btu's at 77% efficiency. The system I was looking at was rated higher than 77% with the thermal storage, but I used those numbers to stay conservative, lest any of you accuse me of putting my wooden thumb on the scales. So, one gallon of fuel oil in my system would be the equivalent of .00747 (115,000/15,400,000) cords of wood.
I then applied a historical price of $175/cord of seasoned firewood, multiplied that by my "oil equivalency factor" of .00747, and again by 10,000 for the number of gallons of oil I was replacing. That comes out to a ten-year wood cost of $13,068, or $1,307 per year. At the price of $175/cord, that meant I was going to burn about 75 cords of wood to replace the 10,000 gallons of oil, or about 7.5 cords per winter.
So, the total cost of my wood boiler investment was going to be $14,945 (system) + $13,068 (wood), for a total ten-year cost of $28,013, or $2,801 per year. This delivers a ten-year cost savings of $10,887, or $1,089 dollars per year. Not bad!
But the wood calculations above brought out one point I hadn't really thought much about. I failed to mention that my house is built into the side of a hill, and the back of the house (and the door to the boiler room) is inaccessible except by foot. To get wood stacked by the back door where it is needed for the boiler means hauling it up and around, and is a pretty non-trivial job. I had been stacking my 6-8 cords out in the front drive, for Sarah to admire, and bringing it armful by armful to a firewood rack for my stove; the thought of hauling an additional seven-and-a-half cords per year up those icy steps called for a little further investigation.
Since this is getting pretty long, and I need to rest my back from the thought of hauling all that wood, I'll give you "the rest of the story" tomorrow.