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Oil Boiler versus Outdoor Wood Pellet Boiler

We live in a 3000 square foot old house that has all new high efficiency windows and has been reinsulated. For the past several years we have used about 1200 gallons of oil for our boiler. (The house is occupied 24 hours a day.)

Our house is heated with old-fashioned cast iron hot water radiators. They are all functional. We do have two rooms in one end of the house that are on a different zone and are heated with baseboard heat.

Natural gas is not an option here and we do not yet have a local source of low-sulphur fuel oil.

We are looking to replace our 40+ year old boiler. In addition to the cost of a new boiler, I assume we would be required to line our chimney, which is currently unlined.

I am wondering whether it might be a good idea to get an outdoor wood pellet burner. No need to line the chimney is one consideration. Carbon neutral is another. The cost of pellets versus oil is another. We're in Maine, where there is obviously a lot of wood. Pellet facilities are increasing and are being facilitated by the state. Oil prices are certainly better this year than last, at least so far, but that situation is likely to get worse, not better. Efficiency of the pellet boiler is 90% and it meets state and federal clean air requirements. You can add a large pellet storage container to the boiler so that you don't have to refill pellets for months. (An auger system moves the pellets to the boiler.) However, the all-in cost is around $15,000, including installation.

Does anybody have any thoughts about outdoor pellet boilers? In particular, does anybody have any thoughts on replacing our oil boiler with an outdoor pellet boiler versus getting a new oil boiler?

Re: Oil Boiler versus Outdoor Wood Pellet Boiler


Since I am not that familiar with pellet boilers, I would recommend a new oil-fired boiler for several reasons:

1) There have been enormous improvements in boiler design since your 40 year old boiler was installed---engineering modifications in combustion chambers & fuel usage will allow you to see a 30% drop in fuel usage over your old unit.

2) Newest models have features like condensing combustion chambers that use up most of the fuel, instead of sending half of it up the chimney as wasted heat as do older boilers from years past.

3) these models are 92 to 95% AFUE efficient, so that only 5% of the fuel is wasted---a 40 year old boiler often wastes 1/2 the fuel as excess heat & combustion products going up the chimney---that's why you burn so much oil.

4) These new units are also modulating in their operation, using a lower flame during mild weather and burning only the fuel needed according to the outside temperature via an outdoor reset (ODR) feature.

5) it just seems that you will have less hassle with an oil-fired boiler over a pellet-fired one---but I'll let others extol the virtues of pellet boilers.

A 30% drop in your fuel usage will reduce your annual usage to about 840 gal/yr, if not even lower.

If you have room, I strongly recommend putting four 275 gal fuel tanks in the cellar & buying all your oil in July/Aug on the spot market when it costs much less.

A flue liner (chimney liner) costs only $500 for parts plus labor & is a one-shot expense--no big deal.

I would recommend a Peerless Pinnacle Condensing oil-fired oil boiler (92% AFUE) with a 40 gallon indirect hot water heatar ($1000).

Another good one is Weil-McLain Ultra Condensing oil-fired boiler---both of these install for less than $10k---get at least 6 estimates--the more estimates you get, the less you'll pay.

Also good is a 3-pass boiler from Buderus, Burnham, Crown, Dunkirk, Peerless, Utica, or Triangle Tube.

Google "energy star boilers product list" to get a list of hundreds of the top boilers in quality and fuel efficiency.

Click onto my name if you want to get more links & info on boilers from my previous posts and others on this forum.


Re: Oil Boiler versus Outdoor Wood Pellet Boiler

NashuaTech, Thanks for all the info. One question, though. I was under the impression that the condensing boilers were not available for systems using regular old #2 fuel oil and that those boilers couldn't get efficiency up into the 90s---at least as yet. Am I misinformed?

Re: Oil Boiler versus Outdoor Wood Pellet Boiler


The oil-fired condensing boilers have been designed for and operate on standard #2 fuel oil---the Peerless Pinnacle gets 92% AFUE efficiency---the Weil McLain Ultra gets 86.5% AFUE--there is also an oil-fired condensing Viessmann Vitola/vitorond which gets 87.5% AFUE.

These are all top rate manufacturers, but since these oil-fired condensers are new on the market, they don't have a track record, & many installers are reluctant to recommend them for that reason.

Some experts have questioned the potential life-span of these units, as being too short---10 years or so before they burn out---who knows!

Because of the uncertainty, I would feel better recommending the 3-pass boilers as mentioned in the previous post, which get 87% AFUE and are a tried & true technology---and should cost somewhat less than the condensing units---this would still have you see a drop of 30% per year in your fuel usage over what you have now.

If you can find an installer in your area that will guarantee one of the oil-fired condensing boilers at 92% AFUE for 20 years, then I would go with that model.

3-pass units: Buderus G215, Biasi B10, Burnham MPO, Crown Freeport, Dunkirk Empire/EV, System 2000, Hydrotherm PB, Peerless PRO/WBV, Slant/Fin Eutectic, Weil-McLain WGO.


Re: Oil Boiler versus Outdoor Wood Pellet Boiler

If you are interested in locally produced/renewable energy, why not supplement a good replacement oil-fueled boiler with a good wood stove or a good pellet stove. The latter won't require a chimney, liner, substantial flue and can be thermostated and have a blower on it. It will also have a small hopper that will last a while.

The advantage of the former is that they work when there is no power and, IMHO, are more environmentally friendly than pellet stoves because cordwood is "processed less" than pellets.


Re: Oil Boiler versus Outdoor Wood Pellet Boiler

NashuaTech, thanks very much for the clarification and additional info. Much appreciated.

cougars1996, thanks for the suggestion. We do already have a wood stove insert in our other fireplace and we use it quite a bit, burning wood from our land. So that part is taken care of. The question about the outdoor pellet boiler has to do with which direction to go to replace our current old oil boiler. Of course, as you know, an indoor woodstove or pellet stove won't do that, but an outdoor pellet boiler could. So that was the origin of my question.

We could get an outdoor wood boiler that has a level 2 EPA certificate and use wood from our land, but then we couldn't ever go away for a few days or more in the winter. The pellet boiler allows for large add-on storage with an auger transfer system that allows you to go months without having to attend to the boiler. That's why I'm thinking of an outdoor pellet boiler rather than wood boiler as an alternative to an oil boiler.

In all likelihood we'll end up with an oil boiler and then maybe further on down the line we could add a wood boiler and have a dual fuel system. I just wanted to take a serious look at the outdoor wood pellet option if there was anybody out there who had experience with it.

Thanks again guys.

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