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Converting Steam radiators to Hot Water

Carl_20 Member Posts: 4
I agree with Andrew. You should also check the vents on the radiators. I have Gorton vents in our steam system and they are great. Speak to Ken Kunz at Gorton. His phone number is (908) 276-1323. He can walk you through venting and tell you where you can buy some near where you live.


  • mmcdade
    mmcdade Member Posts: 3
    Converting Steam Radiators to Hot Water

    OK, I am changing out an old steam boiler for a Buderus 142-24 with a indirect HW tank for 1600 SQ FT apartment.I want to convert the cast iron radiators to hot water. Told by several heating guys that shouldn't be a problem with my radiators. However, one technician said since my steam system is a one pipe in to each radiator, that instead of converting it to a 2 pipe system. That there is a new value that attaches to the one pipe cast iron radiator that does both the return & send for hot water. I can't find information on them anywhere. Anybody use these yet?
  • ALH_4
    ALH_4 Member Posts: 1,790
    Why convert?

    First of all, why the conversion? Keeping it steam asks for far fewer problems and costs far less. One of the bigger problems will be the condition of the cast iron radiators. They can leak once filled with water, and removing plugs frozen in place by decades of rust can be very difficult.

    Assuming the changeout plans are set in stone, unless there is quite a bit of value to those old cast iron radiators it will save money to replace them with steel panel radiators with thermostatic radiator valves and run new pipes to them. I have no idea how you could circulate water through one pipe that dead ends at a radiator. There are ways you can connect both pipes at one end, but that takes more than just a different valve.

    All-in-all, it is wisest to either replace the whole system or stick with the steam. The savings of the efficiency of the condensing boiler will very likely pale in comparison to the initial cost of the conversion. The money is better spent reducing the heat loss.
  • mmcdade
    mmcdade Member Posts: 3

    I guess I could keep it steam, but I plan on never selling th house, so I figured I would save in the long run. Maybe not, but one quote I got for replacing the steam boiler with another one was about the same with converting it to HW with the Buderus.

    They are very ornamental radiators in a 100 yr old Victorian house, so I'm trying to save them.
    As far as the value, I think the technician said it had one flex pipe that went straight in and another one that could be pointed to the top of the radiator.

    I also have replaced 21 old windows and will be doing any old doors as well. Or course more insulation is always a smart thing to do. Still you make some very good points, so perhaps I will stay with steam. Have to do some more research.

  • Noel
    Noel Member Posts: 177
    That would take care of the radiator

    How would the water that comes back out of the radiator get down to the boiler?
  • Andrew Hagen_2
    Andrew Hagen_2 Member Posts: 236

    Staying with the steam really should cost quite a bit less than converting. It's not as simple as just removing the old steam boiler and installing a hot water boiler with a pump and filling it with water, particularly with a 1-pipe steam system.

    Also of concern is that the radiators were sized for 215°F steam, not for 180°F water. Having reduced the heat loss, you might be ok, but it is worth doing the calculations to be sure.

    There are ways to zone steam systems with thermostatic radiator valves that control the air vented from each radiator. Danfoss makes some nice ones with vacuum breakers.

    You would probably burn slightly less fuel by converting. However the investment to do it correctly is probably far more than to repair the steam system correctly, and the it might take decades to recover that investment.

    You might invest in a couple of Dan's books on steam at the Online Store before making your decision. There is no greater authority on the matter.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    I'd look real hard at those quotes

    there's a whole lot more labor involved to run new return piping. I assume they plan to use the existing piping as well as the radiators, which can be very risky. Hot-water needs over 10 times the pressure of steam, which does a very good job of finding any weak points in the system and springing leaks. I've seen botched conversions that leaked rather badly because of this.

    My company does not recommend or perform this type of conversion, and will not work on a system that someone else has converted. Period.

    Why ask for trouble? Keep the steam. As far as new residential steam boilers go, the Burnham Mega-Steam is the efficiency champ.

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • Jamie Hall
    Jamie Hall Member Posts: 23,310
    I don't think so...

    by the time you get done repiping and replacing the boiler, your capital investment is durn near guaranteed to be greater than any conceivable savings you might get from lower fuel consumption -- which will be minimal anyway. Anything you can do with HW can be done with steam and, if the steam system is already in place, usually it's easier and cheaper in steam than in HW. Keep the steam.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Edward A. (Ed) Carey_3


    Something is wrong with the quotes that you have received. The steam installation is overpriced and too high, or the conversion price from steam to water is too low.

    Converting a one pipe steam to FHW is a very labor intensive project. I have personally and successfully done it through the homeowner's insistence, however, I really took the time to work it our thoroughly, and avoided the obvious problems associated with the job.

    The complete conversion of one pipe steam to FHW with a new FHW boiler should cost about three times as much as the well done installation of a new steam replacement boiler under your existing pipe and emitter system.

    The return on investment in fuel savings will not pay for the conversion in any reasonable period of time.

    Find a contractor who really understands steam heat. Install a new and properly designed steam boiler. Make sure that your system and emitters are in good condition and operating properly.

    Thermostatic valves would be a nice touch. If there is any doubt replace the vents, Check and correct pipe pitch and elevations. Assure that your returns are clean and open. Assure a tight and leak free pipe system. In the end you will have a very cost effective and comfortable system.

    Use your head not you wallet to solve this issue.

    Good Luck

    Ed Carey
  • mmcdade
    mmcdade Member Posts: 3
    Re: Converting Steam radiators to Hot Water

    Sounds like I have to get some more quotes on replacing my steam system.
    Thanks everyone!
  • Timco
    Timco Member Posts: 3,040

    Here's one way of doing it...I got them this way. the dining rad was a one-pipe steam and had leaks...see the thread 'what a beauty' to see how I fixed the leaks!

    Just a guy running some pipes.
  • Bruce Stevens
    Bruce Stevens Member Posts: 133
    And how much is it

    going to cost to rent that dinning room radiator.

    Seriously nice looking job
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