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should I replace my gas boiler?

Mar2012 Member Posts: 1
My 33 yr old Repco gas boiler (gas forced water heat-2 zones) works OK. Should I replace it with a more efficient furnace, or wait until it breaks? Our 1500 sq. foot house uses 900-1000 therms a year (heat, DHW and gas stove). How long should a boiler last? 


  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    How long should a boiler last?

    I am a homeowner, not a heating professional. I have experience with only one hot water boiler, a GE from 1950. I had it removed May 2009. In that period of time, I had to replace the burner, and because GE did not make them anymore, my heating contractor put in a Beckett with flame-retention head.

    It is on pages 10 and 11 (they say 11 an 12 at the top of the pages) of this:


    So it lasted about 60 years. It was still working OK, and was not leaking even though I lowered the aquastat so it ran between 130F and 140F, so it was probably condensing. It was surely not designed to condense.

    It is my impression that new boilers are not designed to last that long, but that is just my impression. I have no statistics. It seems to me that you should not wait 60 years to replace a boiler as long as fuel prices are too high (when are they not?).

    If your present boiler is 60% efficient and a new one could be 95%, you should be able to figure out the payback interval. If you plan to stay in that house longer than that, you might consider replacing.

    Now to get 95% efficiency, you would need to run a mod-con boiler with outdoor reset. Even then, it would depend on your heat emitters as to whether you could get 95% from your system. If you have a radiant slab heating, you might well get it. If you have a just-barely large enough baseboard system, you will probably need to put 180F water through them and you will probably not get that much efficiency.

    In my house, I have a radiant slab so I can get about 93% with it, but my upstairs zone is baseboard. I greatly increased the size of the baseboard so I could run water between 110F and 135F so I get condensing all the time. But on really cold days, I probably get closer to 90% efficiency than higher amounts.
  • Tim McElwain
    Tim McElwain Member Posts: 4,593
    You are on borrowed time

    it is time to up grade to a more efficient system either a Mod/Con system or one a little less efficient but staying with the cast iron boiler you have been used to.

    Has any work been done on the house in recent years new windows - added insulation if so your heat loss has changed so a smaller unit may be needed?

    What do you have for emitters radiators, baseboard etc? No matter which way you go outdoor reset is a must.

    More important than all of that however is the contractor you hire and what his expertise and experience brings to the table before any installation is accomplished. Does he agree to do a heat loss? Does he own a combustion analyzer and know how to use it? What are his references? Do not always look for the low bidder if you are going to get into the bidding process. How much experience does he or she have with Mod/Con equipment and installation?
  • Momnprof
    Momnprof Member Posts: 2
    Seemingly outrageous quote

    My house was built is 1930. All brick and plaster walls (Not sure if that is relevant, but thought I'd add it). My house is approx 4500 sq ft.

    My boiler failed this past spring. After several weeks of vicits by the plumber and an engineer, the plumbing contractor came through with a quite for a new Vitodens 200 condensing boiler -- 26,000.

    This seems outrageously high to me given that the prices for the boiler itself that I've seen online do not exceed 6000. Yes it is true that they have to take out the old boiler, and there are six zones to account for, but I need some help in assessing this price.

    Thank you
  • Steamhead
    Steamhead Member Posts: 16,230
    We do NOT

    discuss pricing on this forum.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    the plumbing contractor came through with a qu[o]te for a new Vitodens 200 condensing boiler

    One reason we are not allowed to place prices here is just because of something like your post.

    I had a old oil-fired boiler replaced by a gas fired one. I did look up on the Internet what I could get a boiler like that (mod-con with outdoor reset), and the price was quite low.

    However, by the time it was installed, the price was about four times the Internet price for the boiler. It seems to me the contractor is entitled to getting paid for his labor, overhead, and profit. The contractor also arranged to take out the old oil tank (but not any possible remediation costs if it leaked). In addition, my old electric hot water was leaking ever so slightly, so it seemed a good idea to replace it with an indirect fired one. Since the boiler was a mod-con, and I wanted maximum condensing, and the baseboard zone was always too cold, I had the system split into two zones, and replaced the six feet of baseboard with 14 feet, All the existing near-boiler piping had to be removed, and all new for P-S two-zone piping, and the piping for the indirect had to be provided. Also, expansion tank, microbubble remover, anti-backflow valve, pressure reducing valve, etc. It all mounts up. So possibly I was overcharged a bit; perhaps not.

    I doubt it is ever as simple as just removing the old boiler and installing a new one that, by miracle, just fits up to the old piping, old piping that is in good condition and entirely suited to the new boiler.

    By the time you put in all the details of exactly what is to be done, the prevailing labor and overhead costs, the profit margin for running the business, and all that, a post asking if a given quote is reasonable or not would be so long, and with so many caveats and provisos that it would not mean very much. And it would not indicate if the contractor even knew what he was doing, or was any good at it. And these last two items are possibly more important than all the rest.
  • Momnprof
    Momnprof Member Posts: 2
    Thank for such a thoughtful response

    Of course I had no idea that pricing discussions were prohibited (so there was no need to take my head off, Steamhead). Rather, I was simply perplexed at how there could be such a price difference. Of course the plumbers are entitled to labor costs. I simply have no experience or data regarding these issues, so I appreciate your information. Thank you!
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