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Replace Steam Boiler vs Convert to Hot Water

John79 Member Posts: 2
I have a two pipe vapor steam system in a 1936 home (VECO system, house about 4000 sq ft). Original boiler was swapped for a Weil McLean gas boiler in 1990's, but failed due to a hole in the boiler at the end of the last heating season. I have struggled over the years getting the system maintained. The plumber who installed the Weil McLean boiler has been good, but runs a small shop, is near retirement, and is very busy and often only able to help me for emergencies (often never makes it out for routine maintenance - too busy with other crises). Anyone else who has looked at the system has generally screwed it up. Boiler now has a hole in it, presumably from a leaking wet condensate return line buried in my concrete basement floor (there are two of those). I have some rooms that are a bit colder, so the system is not in perfect balance. Doubt any of the convector valves or traps have ever been maintained or replaced in 80 years. I have quotes for steam boiler replacement or conversion to high efficiency HW system (using existing risers, dry returns and radiators). The HW conversion is more expensive, but when you take into consideration repiping the wet returns (not necessary with the HW), doing deferred maintenance on the convector valves and traps, and relining the chimney (included in the HW quote), the price difference is not huge (20-30% difference depending on the quote). Assuming a successful conversion, I'd expect much easier maintenance on the HW system. Given the struggle I have had finding competent maintenance help for my current system, that is a significant factor. On the other hand, I know the VECO system was supposed to be pretty good, and I certainly don't want sprinkler systems my walls (all my convectors are recessed in my walls and all the risers are hidden in the walls). The company quoting the conversion has done a few dozen using existing pipes and convectors and claims to have only had one leaking riser so far. They pressure test everything first. Been struggling with this decision for a few weeks now. Read Dan's books, but still stuck. Any thoughts very welcome.


  • BobC
    BobC Member Posts: 5,480
    Where are you? maybe one of our contractor members is in your general area. I agree that finding a knowledgeable steam guy is tough and having unskilled people working on the system usually means trouble. It's worth some real effort to find someone who understands the system you have. Once a steam system is working right they take very little care, traps and vents have to be changed once in a while but that is about it. In 35 years my system has been serviced ONCE (primary control failed) outside if yearly cleanouts when it was still oil fired

    How is the insulation in the house? You can't get the same amount of heat out of a convector with hot water as you can with steam. If you don't have a lot more EDR than you really need I don't see how a hot water system could be as efficient as a properly working vapor system. For good efficiency you need low temperature emitters to get into the condensing mode where you can get that high efficiency and that means you need a lot of convector radiating area.

    No matter what you do the valves and traps have to be addressed so the buried wet return is the one thing that has to be addressed for steam. Does it have to be a buried return? If you can run it above the floor the costs go down a lot.

    Will your contractor guarantee the system will work as you expect, if he won't you could get nickel and dimed to death (with BIG nickels and dimes) by unforeseen problems.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
    STEAM DOCTOR Member Posts: 2,040
    Ditto to what Bob said. FYI, good hot water pros are also hard to find. Has anyone done a heat loss calculation? Absolutely necessary for hot water heating
  • Fred
    Fred Member Posts: 8,542
    Post your location on here and let's see if one of the steam pro's here can help you out. I doubt converting to HW will resolve anything, not even your concern for skilled service people. It sounds like you need a new boiler, a couple wet returns replaced and a good steam Pro for on-going support. All very do-able and a two pipe vapor system is about as good as it gets.
  • Jamie Hall
    Jamie Hall Member Posts: 23,635
    Your expectation of easier maintenance on the hot water system is not true. Sorry about that. They take just as much work, if not more -- particularly the high efficiency boilers.

    Further, keep in mind that all you should need to replace for the steam system to work is the two wet returns. Your hope of using the existing piping and radiators for hot water may disappoint you, since the pressures for hot water are much greater than for steam, and you may find that you have leaks. Also, you may find -- it having been a vapour system -- that all the radiator valves will have to be replaced, as well as removing all the traps.

    Bottom line: keep the steam. Vapour steam is one of the very best ways to heat a structure. Find someone who can properly install your new boiler and bring the system up to snuff. As has been said, where are you? We may know of someone capable in your area. If not, and you can find a really good local plumber who is willing to learn, working on steam isn't rocket science and we can help a lot!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 16,996
    edited May 2016
    What Jamie, Fred, SteamDoctor and BobC said. I'll add that pretty much every conversion I've seen has had problems- leaks, rooms too hot or too cold, you name it. There is one yuuuuge contractor around here that has been really pushing these conversions, and from what I hear just walks away when they don't work right. One of these days someone will succeed in taking them to court and winning.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • PMJ
    PMJ Member Posts: 1,265
    I'd be too afraid to convert my two pipe vapor to HW. Can't imagine there aren't places where pressure water wouldn't leak out in all that old piping. It is very comforting to know that there is no water in the walls upstairs. It does a lot of damage quickly if it gets out.

    Also, do they put something in the HW system water to keep it from freezing that one time you had no heat on the coldest day of the year? My uninsulated walls would go below freezing quick and those old pipes wouldn't have a chance. It is great not to have to worry about all that with the steam. Even the Mouat traps drain dry when no steam is happening. Nothing to freeze anywhere.
    1926 1000EDR Mouat 2 pipe vapor system,1957 Bryant Boiler 463,000 BTU input, Natural vacuum operation with single solenoid vent, Custom PLC control
  • John79
    John79 Member Posts: 2
    Thanks for all the helpful thoughts. I am in Delaware County PA, next to Philly.