One question re:

The Pelix burner setup is pricey. (I was quoted almost $5K) and does not address the issue of ash cleanout, leaving it to the design of the boiler.

Are you referring to the Pellergy system (http://www.pellergy.com/)?

A 40lb bag of premium hardwood pellets that sells for $3.88 at Walmart in Biddeford, ME today (yes today, I’m going there again this afternoon to buy some more) contains a minimum of 320,000 btu.

A pound of premium hardwood pellets contains between 8000 and 9000 btu. Although 8300 is typical, I’ll use 8000 for this example since it’s the lowest possible value and will place pellets in the worst possible position for this comparison. There is no sales tax on pellet fuel, so that is not a factor.

A gallon of #2 fuel oil that sells for $3.449 from R&R oil of Arundel, ME today contains a maximum of 140,000 btu. #2 Fuel oil typically contains between 135,000 and 140,000 btu per gallon. I’ll use 140,000 since it places #2 fuel oil in the best possible position for this comparison. There is no sales tax on fuel oil for residential use so that it not a factor.

Based on the above current prices and btu values:
Cost per 100.000 btu of #2 fuel oil is $2.46
Cost per 100,000 btu of premium wood pellets is $1.21
(assumes 8000 btu/lb on pellets)

Prices will fluctuate on both fuels, so I usually say that heating with pellets costs slightly more than half of heating with oil, even though it’s really slightly less at this time here in Maine.

Pellet appliances are typically MORE efficient than oil fired appliances. Not a lot more, but usually more. A typical modern oil fired boiler runs about 84% steady state efficiency. Many pellet stoves run in the low to mid 90s. My own converted pellet boiler runs 84%, unchanged from firing on oil according to my Bacharach combustion analysis kit. No efficiency gain there, but I cut my fuel cost in half.

I do burn gasoline in my truck to bring the pellets home. In my case, I usually do it on my way home from work since I go right by there, so my fuel cost is negligable, but even if I had to drive 20 minutes each way to go get pellets, that’s $10.00 worth of gasoline in my little Ford Ranger, so it would barely effect the cost. (yes you really can put a ton of pellets in a Ranger if you drive carefully)

Not all pellet stoves require that the fire be maintained at all times, many have hot air or hot surface ignition and can be controlled by a thermostat. It’s pretty much like anything else, you get what you pay for, but “sweat equity” does count in a big way with pellets. Buy a good stove that works well with cheap pellets. Don’t skimp here. You don’t want to be addicted to softwood pellets for $250.00 a ton because you found out after you bought the stove that the cheap pellets form too much clinker and you have to clean your burn pot daily.

Do the research and find one that works well with cheap pellets AND has a thermostat. Install it as supplimentary heat and watch your oil bill shrink to nearly nothing while enjoying the knowledge that your oil system will take over if the pellet stove ever fails.

I won’t be so arrogant as to try to calculate your return on investment for you, you obviously have the ability to do that and you have the variables that are unique to your home and lifestyle as well, but I think if you crunch the numbers on this, it’ll be worth your while. I’d be very surprised if your ROI is more than 2 years.

I converted my boiler to fire on pellets and I cut my heating bill right in half from heating exclusively with oil.

Last year I cut, split, and stacked 6 cords of hardwood from my woodlot and burned it in my wood furnace, using the oil system for hot water and as a backup, but there’s a limit to the practicality of “sweat equity”. 6 cords of wood is a lot of work. It was cheaper, for sure, even cheaper than pellets because I own the woodlot, but too much work to be truly practical. That’s why I went with pellets.

Pellets make a nice compromise in this way, but you’re absolutely right, they aren’t something you can just set it and forget it. Handling 40 lb bags of fuel isn’t nearly as much work as most people think though. It’s like handling big bags of dog food. The bags are tough and will take some minor abuse gracefully. I can unload and stack a ton of pellets into the garage in 15 or 20 minutes by myself and I’m not a fitness freak by anyone’s standards.

The auger jam thing is easy to deal with. Simply let it run out of pellets once a month and it’ll clear itself of fines after the last of the pellets are gone. The fines end up in the burn pot and they burn too, so it’s not wasteful. No fines = no auger jams. The absolute worst thing you can do to an auger system is to never let it run out of pellets because it will fill up with fines and jam.

With proper forestry management practices, pellets are a sustainable renewable resource. The state gives tax breaks for tree farming and if everyone in the state converted to burning wood pellets, the sensible thing to do would be to continue to recycle waste product, but instead of raping the forests for the rest, farm fast growing pulpwood to make pellets from. It makes sense

In all fairness though, pellets are not a carbon neutral resource. They create a carbon debt of about 25 years in the greenhouse gases they produce. Not ideal as an enviornmental solution, but a whole lot better than that of fuel oil.

Importing a complete boiler starts at around $15K, so it’s a solution that makes rich people feel all warm and fuzzy about themselves for burning a greener fuel, yet offers little practical value for the masses.

Since I don’t have deep pockets but I do have background in oil burner service (licensed), metal fabrication, and last but not least, microprocessor programming (yes, it’s a bit of an unusual combination), I’ve decided to build my own out of things that we can all buy off the shelf here in the US.

The hopper began life as a 55 gallon barrel. I built an auger system by using a commercially available auger motor 2rpm CCW ($65.00 / Ebay). I bought 5 Rotodigger RD-2 garden augers (put them in a drill to bore holes in a garden to plant bulbs, etc.), cut them in a bandsaw and welded them all together to form an auger and made the housing out of 2″ black iron pipe. I put the barrel on a stand made from rebar and 1/2″ black iron pipe,

I could have sliced and tapered the bottom of the barrel to make it feed every last pellet in the hopper, but it’s just as easy to pour an extra $4.00 bag of pellets into it to get the taper at the bottom instead of spending a whole day with a cutting wheel and a mig welder.

The burner began as a piece of 1/4″ plate that I cut to fit the opening to replace the cover on my boiler where the oil burner gun bolts in. I made the burn pot by welding a piece of 4″ angle iron to the plate and lined the angle iron with firebrick that I bought at tractor supply and cut on a table saw with a masonry blade. The feeder tube is 1 1/2″ black iron pipe. I slotted the bottom edge of the firebrick with the masonry blade to allow air to be blown in between the firebrick and the angle iron.

The intake plenum is a bit hard to describe without a picture ot it handy, but to summarize it, it’s a steel box on the outside of the plate that allows me to divide the intake air between over the fire and under the fire using a damper.

The ignitor is the guts of a heat gun, available at any home depot or lowes store. It blows down a piece of 1/2″ black iron pipe that goes into the intake plenum and comes out just short of the upper (over the fire) inlet port so it heats the pellets until they ignite. I tried using the Chinese $20.00 heat guns from the local discount warehouse, but the brush holders in the blower motor fail in a week and a half.

The combustion air blower is a blower fan from an old dishwasher. It was given to me by a friend and I don’t know the make and model of the dishwasher that it came from. Suffice it to say as a combustion air blower, it’s overkill. I’ve got most of the inlet plugged off and only need an opening about the same area as a US quarter.

In my particular sutuation, I don’t have much of a chimney. I have about 10′ of type L woodstove pipe going through the ceiling and roof of my boiler room with vent cap on the top. Worried that I’d not have enough draft, I installed a power vent between the boiler and the flue to assure that I’d never back hot gases up into the feeder tube. I monitor the feeder tube temp anyway so if that power venter ever fails, the controller will shut it down and lock it out if the feeder reached 300 degrees.

I’m sure the power vent is a contributing factor as to why I need so little combustion air from the blower and without the power venter, I’m sure I’d have the inlet open to something larger than a quarter, but it works reliably and it’s backed up by a failsafe in the controller so I’ll leave it set up like this. Someone else who has a good chimney may not need the power venter.

A new power venter is a few hundred dollars, but this one was sitting in my shed for the last 15 years or so. I took it in, cleaned and inspected it, lubed the bearings, and most importantly I sealed everything on it with high temp RTV sealant so no sparks or hot gases can escape.

The controller is the tricky part. It’s an off the shelf PIC microprocssor connected to solid state relays (Ebay, $6.50 each) by a darlington array. The PIC microcontroller won’t power the solid state relays on it’s own without exceeding the current ratings of the PIC, so I used a darlington array that will handle the current. It took me three days to build the circuitboard and write the software for it and another two weeks to get it fine tuned on the boiler. I’ve got about $200.00 invested in the controller, enclosure, relays, indicator lights, and all the related hardware.

It’s been up and running for about 6 weeks now. Is it finished? Nope. Almost ready to start on phase 2.

Phase 1 has been heating my home reliably and for about half the cost of heating with oil. I’ve been buying premium hardwood pellets for $3.88 per bag ($194 / ton) at Walmart. These are pellets from Maine Wood Products. I know there are other pellets out there with less ash, more softwood, etc., but these are the cheapest pellets I can find and they work just fine.

So after running it for 6 weeks I’ve stopped chasing the gremlins out after week 2, but I still see some room for improvement.

My boiler is a Biasi 4 section cast iron unit. It has a very tiny firebox that doesn’t hold a lot of ash. I have to clean it out twice a week during the heating season here in Maine (takes 15 minutes). In the space under the burn pot, I’ve got enough room for about 4 days worth of ashes OR… another small auger to draw out the ashes into a stainless steel container to hold them until I dump them. That’s going to be part of phase 2.

Phase 2 will begin with another burner made from scratch. Instead of using angle iron and fire brick, I’m going to try using 316 or 310 stainless steel to make the burn pot and see how that holds up. 310 will take higher temperatures, but it’s also more vulnerable to crystal fatigue at high temps, so there’s one way to find out…

Meanwhile, my stock firebox cover plate and my Riello burner for #2 fuel oil sit on the floor in the boiler room. I can convert it back to oil in about 20 minutes if I ever had the need to do so. You don’t run an experimental burner as a primary source of heat in the middle of a Maine winter without a backup plan…

So this is heating my home comfortably and reliably. My feedrate for the pellets is measured at 12.38 lb per hour, this is comparable to a .75gph nozzle on a conventional oil burner running 100psi behind the nozzle. It costs about half as much as heating with oil.

I’ve done a full cleaning on the boiler about a week ago, but it was not necessary. I did it just to see what was in there. My burner design burns the pellets from underneath with insufficient combustion air, The secondary air, most of which comes down the feeder tube with the pellets, causes the wood gases to burn above the pellets and the flames from that reach into the upper portions of the boiler’s heat exchanger and it burns itself clean. Other than a little bit of fly ash, there’s nothing in there at all. Even the caked on crap from burning oil is gone (I did not clean the boiler when I took out the oil gun and installed the new burner).

So where is this technology going? I’ll never manufacture it to sell as a turnkey conversion package. I’d get sued within the first year. What I will do is sell parts for the DIY’er to build thier own once I’m convinced that my design is ready for that.

Insurance is another issue. You aren’t going to get homeowner’s insurance with a DIY pellet burner in your boiler. Most european boilers don’t carry ASME ratings, nor are thier burners UL approved. Unless the political climate changes, you probably won’t have much luck with that avenue either. You might slip it by your local agent, who in turn might slip it by the underwriter unnoticed, but if anything ever happens to that boiler and it does cause a fire, you’ll need a lawyer to get your settlement check for sure.

So I guess the moral of the story is that if you aren’t 110% sure that the thing isn’t going to burn your house down, then don’t put it in there to begin with. Wood stoves have been around long before the oil burner. It’s pretty hard for the insurance companies to categorically deny woodstoves, but they do make us jump through some hoops to have one. Converting an oil fired appliance to burn pellets is new and scary to them….

Most of Europe is heating with wood pellets. Sweden and Finland are the biggest consumers of wood pellets in the world, but it catching on everywhere. Everywhere but here…

Our government and out insurance industries all think that we Americans are too stupid to empty the ashes and to check the draft once in a while. Even though we have safeties on the controls to catch us if we forget, it doesn’t seem to be good enough for the people who dictate what we can and can’t have in our own homes.

Right now this technology is widely available and at much more affordable rates in former Soviet block counties such as the Czech republic than it is here. Bosnia and Bulgaria have this technology readily available to them and we don’t. Now isn’t just that a kick in the Balkans….

So yes, the technology is here, but it’s still taboo and will continue to be until someone with deep pockets wants it to be accepted here.

I never did get an oil tank to replace the underground one I had removed — just couldn’t figure out where to put it since my house is very odd in that it doesn’t have a basement, and I didn’t really want the tank in my garage. I will be installing a propane heater as a back-up for times when I am not home (the down side of the pellet furnace is that it needs to be fed every 1-2 days). If I sell this house, which I may in the next year or two, I’ll have 2 sources of heat so hopefully that will be enough for prospective buyers. And I still have the oil furnace if they want to install their own oil tank!

Interestingly, when I refinanced my mortgage a couple of years ago, the appraiser just loved the pellet furnace. I know I got brownie points in the appraisal for my “alternative heating source” (I think that’s how it was written up).

I just finished paying for my pellet mill and I am making arrangements for delivery. I will keep in touch.
Tom

Really? I’d be curious to hear more about that.

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