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To convert or Not

Cdav Member Posts: 15
My Weil Mclain gas steam boiler (installed in 1988) started leaking from the bottom yesterday and I was told I needed a new boiler. The Weil Mclain is 140,000btu input and 112,000btu output...a single pipe system and my place is about 1400 sqft. I was pitched the idea to convert to an all in one hot water wall mount system that would also replace the hot water heater and would run more efficient. With the conversion, they will swap out all pipes to copper pipes but keeping the same radiators. The cost would be about $4K more than just replacing the current boiler with a new burnham. This sounds a bit expensive now but I'm thinking about it as the efficiency should save me in the long run. It is also an attractive thought as I would have more space in that room with both the water heater and boiler gone. So, hear are my question, 1) does such a system exist? 2) Can the steam radiators be reused? 3) Is hot water more efficient than steam? Is it worth the conversion assuming I'll be in the house for about another 10 years? 4) What companies carry all in one system wall mount systems? My house has a total of 9 radiator.



    ALIGA Member Posts: 194
    one peice of advice

    Calculate the EDRs of your radiators to determine boiler size. In most cases the boilers were oversized.
  • Paul48
    Paul48 Member Posts: 4,469
    edited November 2012

    Those radiators have lived their lives at 2lbs of pressure or less, and now you will ask them to hold 14 lbs or so. Those  radiators will emit approximately 25% less heat with hot water vs. steam. What you're describing , is known as a combi-boiler. They produce very limited hot water, and a better option is an indirect hot water heater, run off a mod/con boiler. There are also venting considerations that come with mod/con boilers.Make sure that everything is included, and any boiler installed will be installed to manufacturers specifications.The boiler is from "88", how old is the house and radiators?
  • Issues

    First off, the overall savings between a properly running steam system and a hot water system are not that great,if at all.  Simple gas fired steam requires virtually no electricity to operate.  High efficiency hot water can require upwards 500 to 700 watts.  Also, most one pipe steam radiators cannot be converted to hot water....so the whole idea is proabably false.  Water systems also can freeze up, so if you have any drafty areas where you have no problems now, you may have them with a water system, especially during power failures or pump failures.  Steam boilers use nearly universal replacment parts.....High efficiency hot water boilers are nearly completely proprietary.  Your steam boiler lasted 25 years (it should last longer than that, more like 30 years or more), high efficiency hot water boilers typically have a much shorter design life.  

    Right now you have a potentially very efficient and very simple heating system.  You will be converting to a very efficient , but very complicated heating system.

    Get a good steam specialest that can properly size and pipe the boiler and take care of any system deficiecies you may have.  This is the recommendation by the
    The Steam Whisperer (Formerly Boilerpro)

    Chicago's Steam Heating Expert

    Noisy Radiators are a Cry for Help
  • Cdav
    Cdav Member Posts: 15
    thank guys

    Paul48, the house was built in 1938 and I'm not sure how old the radiators are but I'm assuming same age. Thanks for the feedback guys and it sounds like not to convert. It is a very simple one pipe system and I think I'll just replace the boiler.
  • Paul48
    Paul48 Member Posts: 4,469

    with a properly sized boiler. You get one chance to do it right. You match the boiler to the total EDR of all the radiators.
  • ChrisJ
    ChrisJ Member Posts: 15,506

    Not only does it not make sense to convert but I'm willing to bet that you have a WM EG-40 which is still being produced.   It would be VERY easy to swap in a new identical boiler especially if the piping was done right.   Even if the EG-40 is oversized swapping in the next size smaller would be just as easy.

    I recommend sealing up any leaks and using water treatment to make sure the next boiler lasts longer.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Cdav
    Cdav Member Posts: 15
    edited November 2012

    ChrisJ, it says E-5. Here are two pic. It is leaking onto the burnings in the first pic.
  • Dave in QCA
    Dave in QCA Member Posts: 1,785
    Conversions often Miscalculated

    I know of two large conversions from steam to hot water that were designed by engineering firms.  In both of them, the engineer failed to notice that the radiators were steam only.  There was no way to bleed the air out, the radiators only filled about one fourth with water and the heating capacity was greatly reduced.  In one of these buildings that I am personally familiar with, attic insulation and storm windows made enoug difference that the building heated unless the weather was VERY cold.  However, the water temps that had to be run were higher than normal, i.e., in the 180 range.  The savings that were projected were never realized.  Overall, it was a waste of time and effort and turned a well operating system into a pile of junk.

    If it were my house, I would NOT convert.
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
  • Cdav
    Cdav Member Posts: 15
    Very helpful Dave.

    Yeah Dave, I replacing is the way I'm going based on the feedback here.
This discussion has been closed.