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.