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brboston21
Cast iron boiler vs. high efficiency stainless steel

We want to replace our 38 year old gas-fired boiler. We live in the Boston area in a single-family split-level home built in 1974. Our existing boiler has an input of 210,000 Btu/hr and an output of 168,000 Btu/hr, which makes it 80% efficient. We have 3 zones heated by circulating hot water.

Everything I read says to get a high-efficiency boiler with AFUE greater than or equal to 90% because we live in the "snow belt" of New England. However, the contractors that we have called for estimates say that we should get another cast iron boiler with efficiency of 80% and a life expectency of 30+ years instead of a stainless steel or aluminum high efficiency boiler because those last only 10-12 years and cost at least $3,000 more. They say that the high efficiency boilers also require more maintenance.

None of them have actually done calculations for our house; they just say that in their experience the upfront + maintenance costs + much shorter life expectency of the high-efficiency boilers does not justify the savings in the gas bill.

Is it true that the high efficiency boilers have 1/2 the life expectency of the cast iron boilers? Is it true that annual or biannual maintenance requirements are much greater for the high efficiency units?

Thanks for your help with this.

brewster
Re: Cast iron boiler vs. high efficiency stainless steel

brboston:

Your questions are excellent and deserve an elaborate response; I wonder if you could revise your personal account so that you can receive personal messages by clicking onto "user cp" above and following the prompts. Thank You.

user cp---->settings & options---->Edit Options---->Receive email from others/enable private messages.

jim hankinson
Re: Cast iron boiler vs. high efficiency stainless steel

I just read an article in P & M Magaine a few days ago that confirmed the shorter lifespan of condensing boilers. According to the Chartered Institution of Building Service Engineers the life expectancy of a condensing boiler is 15 years. According to UK Energy Saving the average is 10 to 15 years.

This should be taken into consideration when trying to figure long range cost of a system. You may save a lot of money during the life of a mod/con but if you have to replace it after 15 years will you have a net savings over 30 yrs?

You can get a mid range efficiency boiler that will last on average 30-35 yrs. It may not save as much money on a year to year basis but could save as much or more over 30 years.

AFUE for hydronic boilers is not an accurate indicator of how efficient a boiler is. Brookhaven National Labs did a study several years ago that showed how much difference in real efficiency there can be between boilers with virtually the same AFUE.

All heating systems should be serviced every year if for no other purpose than to make sure the vent system is clear and in good repair and that all safeties function as they should. It doesn't make any difference if it's gas or oil, have it checked every year.

brboston21
Re: Cast iron boiler vs. high efficiency stainless steel

OK, private messages are enabled.

brewster
Re: Cast iron boiler vs. high efficiency stainless steel

PM issued.

johnjh2o
Re: Cast iron boiler vs. high efficiency stainless steel

Why not post it here for all to see?

John

JLMCDANIEL
Re: Cast iron boiler vs. high efficiency stainless steel

Information sent via PM could be misleading or false and not subject to peer review, be cautious.

Jack

johnjh2o
Re: Cast iron boiler vs. high efficiency stainless steel

That was my thinking I just didn't say it.

John

brboston21
Re: Cast iron boiler vs. high efficiency stainless steel

Thank you all for your replies.

I was referred to another site at which a question almost identical to mine was asked and answered, although the answers were not very helpful.

To summarize, someone on that site mentioned a $3500 rebate from NStar if you replace the boiler with a high-efficiency model by Oct. 31. Unfortunately, National Grid does not participate in this rebate.

Other points people made:

    Consider how long you will live in your current house.
    Condensing boilers do require more service calls.
    Condensing boilers still have bugs to be worked out.
    New boilers have an automatic setback system which keeps the boiler at 120 degrees rather than the old fashioned 180 degrees.

Other advice had to do with the insulation of the house, which is irrelevant to which boiler to choose.

I am still undecided about which way to go. My husband is leaning toward the less expensive cast iron boiler.

JLMCDANIEL
Re: Cast iron boiler vs. high efficiency stainless steel

My problem with HE units is the service costs. From what I have seen you end up spending more on maintenance than you save of fuel.

Jack

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