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Boiler Replacement (Cast Iron vs. Copper Finned)

Greetings, All

I manage a small home owners association. We have a six unit building. The old cast iron boiler was flagged by the state inspector. It's been in service for 42 years and needs to be replaced.

I have three companies submitting proposals for the project. The first proposal included two 232,000 BTU cast iron boilers. The rational was that during times when it's not extremely cold and the demand for heat is low, only one boiler needs to run, reducing the utility cost during seasons where heat is needed. We're in Denver, CO. The total cost for demolition/removal of the old boiler and installation of the new, with some additional costs to bring the system up to code, $25K.

The next proposal is on its way. It will include a copper finned boiler instead of two cast iron boilers. The company that wrote the first proposal made a point of saying that I shouldn't get a copper finned boiler. "They're inferior and it will skew the proposal." I guess part of that means the cost of a copper finned boiler is less than that of a cast iron boiler.

Are copper finned boilers inferior to cast iron boilers? If so, what's the difference? Is it merely a matter of copper finned lasting only 25 years rather than 40 years like the current cast iron boiler? Are there maintenance costs associated with copper finned that I need to be aware of? Is the cost of a copper finned boiler over of its lifetime more than the cost of a cast iron boiler?

The building uses cast iron radiators in each unit to deliver the heat. Those will stay in place.

I'm a software engineer. I know little about building facilities. Any information you can provide will be greatly appreciated.



Ron remodeler
Re: Boiler Replacement (Cast Iron vs. Copper Finned)

cast iron used to be pretty darn reliable and can stand the stresses over time well. I am not sure that copper fined has such a long track record for longevity or endurance.

Re: Boiler Replacement (Cast Iron vs. Copper Finned)

I had an interesting discussion with the guy who came out today for an estimate. I asked him, "Would a copper finned boiler last as long as a cast iron boiler?" His reply, "Would you really want it to?"

His rational: Yes, a copper finned boiler has maybe half the life of a cast iron boiler, but it offers two important things:

  1. Low operating cost - important but the second item is what really caught my ear.
  2. The opportunity to take advantage of new, more efficient boiler technology sooner.

That was an interesting observation. He mentioned that there's some very impressive tech coming down the pipe for commercial and residential heating. A copper finned boiler may only have an 18 to 20 year work life, but it would make available higher efficiency technology at an earlier time frame.

I won't be living in this building in 18 to 20 years, but someone will. I'm not totally sold, but it's something to think about and consider.


Re: Boiler Replacement (Cast Iron vs. Copper Finned)


You need a lot more estimates/quotes from local installers--the reason for this is that the equipment they suggest & the $$ quote for the job WILL VARY WIDELY over say, 6 other installers.

Thus, consult the Yellow Pages under "Heating Contractors", "Fuel Oil Dealers", & "Heating Equipment Suppliers"

Oil dealers are also licensed to install gas-fired equipment and heating equipment dealers have a daily contact with heating equipment installers, so would be more likely to refer installers that would meet your needs.

This is more of a COMMERCIAL-type installation as opposed to a residential install---it sounds like you have nearly 12,000 sq.ft. of space to be heated, where a typical home is only 1/12th your figure.

Thus, 2 boilers running in tandem are often recommended for this setup---one comes on to heat the 12k feet & the 2nd boiler kicks in on cold days when the 1st boiler can't handle the heating load.

Copper-fin boilers are a small piece of the market---the largest sales in boilers is with the traditional cast iron heat exchangers, or the newer stainless steel condensing/modulating boilers.

In my opinion stainless steel heat exchangers with a condensing capacity (especially if you have gas heat) are much more efficient & the equipment will last lots longer than copper---current stainless steel boilers are rated at 95% to 96% AFUE efficiency---that means only 4% of the heat is wasted up the chimney/flue---cast iron boilers are rated closer to 85% to 88% AFUE efficiency---so 15% of the heat escapes up the chimney--this makes a big $$$ difference in annual fuel costs---so buy the most efficient boiler you can afford.

Outdoor reset is a must these days & usually comes with the new boiler(s)---outdoor reset heats the boiler water to only 100 degrees on "not so cold days" (as opposed to 180 degrees all the time) & thus saves lots of $$$ on fuel expenses.

To estimate how much boiler you need (in btu/hour capacity), take the TOTAL SQUARE FOOTAGE of all rooms & spaces to be heated in the building & multiply by 40.

Thus, if you have 12,000 sq.ft. of total space X 40 = 464,000 btu/hour heating need for the entire building---this is a very rough estimate designed to give you a ballpark figure, and a computer-driven HEAT LOSS CALCULATION (MANUAL J) must be done to get an accurate sizing calculation for how big a boiler you need.

All prospective installers should do a comprehensive HEAT LOSS CALCULATION on their computer to calculate the size of the boiler (or boilers) to be installed--otherwise they're liable to put in a boiler that's too big & wastes fuel.

Consult some of the previous posts below to get some background information on what to look for in names of boilers & types of units.


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