replacing 50-yr-old oil steam boiler

Al Letellier_9

As to your question about the boiler. A 1953 vintage boiler is way past its useful life and changing it would yield the greatess change in efficiency. It simply wasn't built for todays burners and doing a conversion would not yield any significant savigns. As to oil or gas, who knows. With a steam system, I think oil is the better buy. With hot water systems and all the new condensing boilers out there, gas may be a better choice. We don't have high efficiency boilers for steam as yet, but today's steamer rate in the mid to high 80% range, way about that old hunk of iron you now have.

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regtor

replacing 50-yr-old oil steam boiler

I've just stumbled onto this site and after some searching I am bit overwhelmed with information. Our 1925 house has an oil-fired steam system, single pipe, with a 1953 boiler (have the records) and a 1980's vintage Beckett burner. The system has been working fine, and over the last several years I have replaced the windows and added as much insulation as possible.

My question is about whether to replace this working system to gain efficiency. Every time I ask a plumber or oil company tech I get a different answer: Yes, you should replace with a newer system as it will be smaller in size and use less oil... No, newer systems are not significantly more efficient than what you have and will not last as long, plus a smaller system with lower mass won't provide any fuel savings... Yes, you should replace the burner with a higher efficiency one... No, they don't exist...

I am hoping the many experts on this board can help me navigate this issue -- should I replace or not?

Then comes the question of whether to convert to natural gas. I've looked at this over the years and on a per MMBtu basis in my region (Boston area), oil has been consistently cheaper than gas for over 10 years -- EXCEPT right now, with somewhat lower gas prices and $3/gallon oil. I have not been able to find a definitive answer regarding efficiency differences between my old oil system and a new gas system -- whether it be a new gas boiler or installing a conversion burner. (Piping is not an issue as I have a one-inch line right next to the boiler) Which provides a higher efficiency -- a conversion burner on an old steam boiler or a new steam boiler?

Any responses would be very much appreciated.

Brad White

Steaming

I agree with Al, if you have steam, oil is the better choice. Put another way, gas can be used more efficiently in other appliances but not so with steam. Kind of a waste of one of natural gas's benefits.

You did come to the right place.

This is where I would start: Measure and document all of your existing radiators. Type/Style, number of tubes per section, number of sections, height and width plus center to center section dimension. What you want is the total amount of radiation expressed in square feet EDR (equivalent direct radiation).

It matters not that your house is insulated and improved, when sizing a steam boiler. (It is excellent that you did so, don't get me wrong here.) Rather, a steam boiler is sized strictly on the radiation connected to it. If it happens to meet the heat loss, all the better.

There are newer boilers out there, the Burnham Megasteam which is getting favorable reviews. Three-pass combustion versus maybe one pass in an older model.

The second thing I would do is map out the near-boiler piping and the steam and condensate piping in general. How much piping of what size and what configuration it is in. If the condensate piping is buried or exposed. Vent locations. Lots of details. Post some photos if you can.

Stick around here and ask questions. I am in Boston also and can advise but that is not why I am here, if that makes sense. There are good steam practitioners especially near the south shore too.

regtor

Thank you for your reponses. Re: EDR -- I've got some homework for this weekend. I have removed one radiator from the system (part of a remodel) so I suspect the old beast is already oversized. There is also one "extra" run of pipe to the master bedroom that has no radiator (sticks out from floor and capped), and it appears it never had one installed. That's the thing with old houses...

With respect to the piping, most of it is exposed in the basement. It is of all sorts of diameters. It is quite a tree, I will try to post a pic this weekend. I have considered insulating the pipes but the old beast is surrounded by (1) the laundry; (2) my workshop; and (3) kids foosball & table hockey; so I figured I need the pipes to provide heat for this "living" space.

Finally, I've done a bit of research and it appears that the best AFUE I can get for an oil-fired steam boiler is 86% (e.g. Burnham MegaSteam) while gas-fired steamers are no higher than 82% (most are 80-81% -- am I missing any gas steamer boilers out there?). So it appears that from a pure efficiency perspective oil is the better buy. Of course, there are other issues such as emissions, but as long as there is no carbon tax the different emission profiles do not affect the economics. As I mentioned earlier, this coming winter appears to be the first one in many years when the per Btu price of oil will exceed gas by quite a margin, but gas's price advantage is somewhat reduced by the the efficiency advantage of the oil steamers (86% AFUE vs 82%). Should a carbon tax be imposed then gas will gain a considerable advantage, perhaps offsetting its efficiency disadvantage.

Thanks again and I will post more details soon.