Should You Upgrade To A High Efficiency Boiler?

by Owner on October 19, 2009

I face a conundrum in my new home, especially after the recent spate of bad weather we’ve had. The boiler is over 30 years old, and just looking at it screams “inefficient!” in my mind. It’s rusting, it’s old, it’s a natural gas guzzler compared to current models. On the other hand, it works perfectly well for its intended purpose: heating my radiators. So my conundrum is whether I should replace it with a high efficiency boiler (which isn’t cheap), or live a tortured life knowing I’m wasting natural gas and contributing to global warming emissions. Grrr.

My rational mind being what it is, I went out looking for some numbers to help bolster the case one way or another. I found the American Council for an Energy-Efficient Economy (ACEEE), and in particular a web page of theirs with a very interesting chart. The chart graphs the energy efficiency of your old boiler and the proposed new boiler, and gives you an estimate of how much money per $100 of heating bills you would save yearly with the more efficient boiler.

Now this is not at all an exact science, because while I might be able to find my old boiler’s original efficiency, I don’t know what the effects of time have been on it. I also don’t know how energy efficient my new boiler will be, although I DO know that the more efficient the boiler, the more expensive it is. Good, long-lasting Energy Star compliant boilers (85%+ energy efficient) are so expensive, in fact, that they’re probably not in my budget (at least according to one estimate I”ve had done.) I may get additional estimates to be sure. But regardless, I know I can get a pretty efficient boiler, of about 80% energy efficiency, at the “reasonable” price of $5000-$6000.

I estimate my old boiler’s energy efficiency to be 55%; I read elsewhere that old boilers had about 60-65% energy efficiency, so I’m factoring in the passage of time.  So if I use a figure of 80% efficiency for the new boiler and 55% efficiency for the old, I’ll realize a savings of about $31 per $100 of yearly gas bills, or about one-third, according to the ACEEE. I believe my yearly gas bill would be $1700-$2000 based on the previous owner’s usage, so that would be a savings of $527-$620 per year.

That’s a yearly return of over 10% on a $5000 investment. I somehow doubt I’d get that in the stock market!

Of course this is a VERY rough estimate–I might use less gas than the previous owner, I might be miscalculating the efficiency of the old boiler. But it’s a very rough rule of thumb for getting a financial picture of the money you’d save with a new boiler.

So am I going to upgrade to a high efficiency boiler? Probably, but I’ve not decided for sure yet. First I’m going to focus on weatherstripping drafty doors and windows, which is much cheaper than a boiler!

{ 2 comments… read them below or add one }

Tom October 27, 2009 at 12:04 pm

I just got one of these energy efficient boilers and although I didn’t see much difference at first, now that I’ve had it for a few months I can really tell the difference (especially on the bill :P).


Digart November 10, 2009 at 11:31 pm

I have replaced my old oil boiler with the high efficincy natural gas model. So far it’s doing amasing, as per my observation, job, to heat the radiant floor in basement and radiators at the main floor. Though, with investment of almost $8,500 canadian, I hope it will be very good in the long run. I have some pictures to illustarate my choice.


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