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Steam Oil to Gas Conversion - which boiler?

KH Member Posts: 4
Hi.  I am having trouble figuring out which boiler I need.  We are converting from oil to gas.  I have gotten a few quotes with different size boilers listed.  Right now I believe we have a 245,000 BTU/hr Burnham steam boiler.  We have a very old large house, but when I counted and measured all my radiators - counting tubes, columns, sections -  I got that I need 146,160 BTU/hr.  This even includes a large radiator on the 3rd floor we don't use.  Our house is not insulated (too cost prohibitive because of many large curved windows.)  We would like to get a Burnham boiler through the gas company.  All radiators have one pipe connecting it.  I have to manually (with the lever) fill our current boiler.   Any thoughts????


  • BobC
    BobC Member Posts: 5,401
    Find the right contractor

    Steam boilers are usually sized by matching the boilers sq ft of steam rating to the total radiators EDR (sq ft of surface area). Your 146,160 btu's works out to 609 EDR so your current boiler appears too big for the job and will waste fuel.

    I'm in the Boston area and I've had the gas company send someone out to recommend a gas boiler to replace me oil fired Burnham v75 (rated at 596 sq ft of steam) and the guy they sent does not understand steam systems. Your best off with an independent contractor who will survey the ENTIRE system and recommend a gas fired replacement boiler, if his numbers don't match yours ask why. If he does not think it's necessary to determine the EDR of the system thank him for his time and show him the door.

    A good contractor will be able to get you any rebates that the gas company offers. It might take some time to find someone because good steam installers are not easy to find, take your time and try to select the right contractor for the job. If you use the "Find a Contractor" tab at the top of this page and search by state you might get a couple of hits.

    I'll be starting the same process to replace my oil fired boiler with a gas fired boiler that you are in a week or two. Getting the right contractor is the most important thing you can do, don't just shop price find someone that knows what they are doing and that you trust. This is good time to do something like that because we will have time to pick and choose without worrying about having the boiler fail on us.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,253
    Make sure you are measuring the radiators correctly

    While most boilers I change out are too large, I often get EDR's from customers that are too small. This is why no matter the job or customer I take the time to go and measure each radiator myself before sizing a boiler. The boilers the gas company has are good but there are other choices depending on what your building set up is that can be a few percent more efficient. BTW Bob i work in Eastern Mass also.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Tim McElwain
    Tim McElwain Member Posts: 4,588
    My recommendation is

    to stay away from atmospheric gas steam boilers and go with an oil steam boiler then install a power gas conversion burner, much more efficient than atmospheric gas. I have put in over 3,500 gas conversion burners so I know of what I speak.
  • Tim_Hodgson
    Tim_Hodgson Member Posts: 60
    Everyone has a good idea.

    Your steam system is sized by the EDR rating of your radiators( sq feet of surface area)

    PLUS the connected piping. You need to create enough steam to fill ALL the piping first then supply even more to fill the radiators. It is common to add 33% - 50% load to handle the steam piping. Your 150,000 btu/hr OUTPUT radiators will probably need a 200,000 - 225,000 btu/hr output rated boiler to handle it all. The key phrase is "output".

    The second issue is how do you handle the condensate returning to the boiler. Most newer boilers have very small water content and the retuning condensate at the  end of the cycle may flood the new boiler. Older boilers could handle a lot of returning condensate  while raising the water level in the sight glass only 1 or 2 inches.

    A small boiler feed pump and water level control on the boiler will solve that issue if you need it. I always try to utilize gravity first, but get a $ on the feed pump as an option so there are no surprises later.

    Good Luck,

    Tim Hodgson
  • CMadatMe
    CMadatMe Member Posts: 3,086
    I'd Stick

    With the oil and install a Burnham MegaSteam, no gas steam boiler is going to touch it's efficiency.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • JohnHenry_2
    JohnHenry_2 Member Posts: 70
    Oil over Gas?

    Even though oil is 3 times the price of gas per BTU?
    The bitterness of poor quality remains long after the sweetness of low price is forgotten.
  • Paul_69
    Paul_69 Member Posts: 251
    oil to gas steam gun conversion

    i have a customer with a williamson owt3 steam oil boiler about 7 yrs. old. i called williamson rep. and said they dont condone or recomend doing a gun conversion and would void warrantees. is this true as i have seen many in other modern boilers? if so how much would the customer save approx. in fuel. if not what would you put in for a replacement boiler and what type of savings.
  • Steamhead
    Steamhead Member Posts: 15,988
    I posted an answer to this

    in your other thread.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
This discussion has been closed.