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Burner Conversion Question - Weil-McLain P-SG0-3

SteamInMA Member Posts: 7
We're closing on a home in MA in several weeks that has a 5 year old  Weil-McLain P-SG0-3. Heating system is steam. Boiler has HW coil on it.

The oil tank is at end of life and there is gas already in the house,

so we're considering converting the boiler to natural gas rather than

replacing the oil tank. We'd prefer to fix this before the heating

season starts.

We're just trying to get through our first heating season in the new

home before making any huge expenditures but we don't want to roll the

dice on the oil tank.

Based on reading here (great resources!) and other places, I thought this system would be a prime candidate for a burner only conversion with a cleaned chimney. However, several plumbers with experience on steam systems have told me this would be throwing my money away and I should just get a brand new boiler plus a HW heater.

They've given various reasons including the following: 1) Gas won't be able to keep up with the tankless HW coil on the burner because it does not burn as hot as oil. Coil will also wear out faster due burner being gas rather than oil. 2) If the boiler has been running on oil, converting the burner to gas is somehow bad for the boiler (not the chimney, the boiler itself) 3) We'll be wasting a lot of gas if we only convert the burner 4) The rebates from the gas company, which I've already priced out and still seem more than we want to spend. All of their gas boilers require a separate purchase of a HW heater.

Is there any reason (safety or cost) that we could not do a burner conversion on the boiler now, keep the tankless on the boiler with a converted gas burner, and add a HW heater in later years?


  • icesailor
    icesailor Member Posts: 7,265
    edited July 2014
    The Madam Judge:

    Judge Judy (Shindlin) wrote her first book and she called it "Don't pee on my leg and tell me its raining".

    Someone peed on your leg.

    (unless they explained that a PSOG-3 is a little short on the combustion chamber area to get a good efficient gas flame.)

    How old is the house and how old is the oil tank?  
  • RobG
    RobG Member Posts: 1,850
    The Answer

    The aswer can be found here. You should read the entire post. If it were mine, I would do it in a New York minute.

  • Steamhead
    Steamhead Member Posts: 15,987
    That P-SGO-3

    does have a small firing zone, but it should run well with a Carlin EZ-Gas burner having a 9-slot diffuser plate. The 9-slot diffuser produces a compact flame much like a flame-retention oil burner does, and should fit that firing zone quite well. We use the same combination on 3- or 4-section Slant/Fin Intrepid and Liberty boilers, which also have short firing zones.

    The 9-slot diffuser came out some time after the burner was introduced with its original A and B diffusers, so it may not appear in earlier setup guides. The A and B diffusers tend to create longer flames, which work well in some boilers but not in others.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,253
    Two reasons converting may not be good money

    1. Boiler is installed poorly, and under or oversized.

    2. Boiler was not maintained well and has a shortened life.

    Photos of boiler would help make a more accurate assessment.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • SteamInMA
    SteamInMA Member Posts: 7
    edited July 2014
    Answering Questions

    Home built in 1949. No idea on oil tank age. Home inspector said it was beyond its end of life and could start leaking anytime.
  • SteamInMA
    SteamInMA Member Posts: 7
    Thanks for the responses

    Reading that other thread, I see mention of converting to a separate

    DHW system, which we planned on putting off until next year.

    Thanks steamhead for the explanation as to why the Carlin EZ-Gas is a good fit for this boiler.


    of these heating specialists have viewed the boiler yet, so they don't

    know if it is properly sized, installed or maintained. They've made

    these comments over the phone when I'm calling to get them out to the

    home to give an estimate for a gas burner conversion.

    If I can, I'll upload some photos of the boiler.

    Yes, I've called those listed under "Find a Contractor" and am trying to get scheduled with one.
  • BobC
    BobC Member Posts: 5,401
    A good move

    I had an oil tank that started to weep a few years ago, the price of oil was getting ridiculous so i decided to switch to gas rather than replace the tank. I installed a Smith G-8 (no longer in production) with the EZ-Gas burner because my Burnham V75 boiler was 13 years old and that particular model was not known for longevity.

    The combination has worked very well for me and I have saved a lot of money on fuel burned. If your boiler is still in good shape I would not hesitate to convert it, just make sure your installer is familiar with the Carlin gun and that he follows the advice about using the 9 slot diffuser plate.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • JeffM
    JeffM Member Posts: 179
    original poster

    I posted the original question on the linked thread about converting SGO boilers. I'm happy to report back that I did have a Carlin conversion burner put on and have been very happy with the results. Our fuel bills are down 40% (in $) from when we were using oil, and the system burns much more cleanly which reduces the annual service work too. The only minor difference that I noted was that the tankless coil didn't perform quite as well after the conversion, but I bumped up the aquastat temp a few degrees on the boiler and replaced the mixing valve cartridge which solved that quite nicely.
  • SteamInMA
    SteamInMA Member Posts: 7
    Thanks for the update on your conversion

    Thank you for following up with an update on your conversion. Always good to read reports back like yours. 
  • SteamInMA
    SteamInMA Member Posts: 7
    Pics of current boiler

    See attached for photos. Did I miss any angles that are useful? I have higher resolution if needed.

    Forgot to take photos of the radiators and measure them to see if it is properly sized.

    Only thing that gives me pause about keeping existing is the tag says it was last serviced in 2011. Does this, or the photos, change any recommendations or advice?
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,253
    Please refer to the manual

    There are so many things wrong I would double check the size of the boiler.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • RobG
    RobG Member Posts: 1,850

    What Charlie said. If the boiler is sized correctly I would re-use it. You still need to have it completely re-piped. It may heat your home, however once it is re-piped and correctly vented you WILL notice how much better and less expensively it heats your home, oil or gas.

    Make sure that you get some proper support on the gas meter rack and gas piping.

  • Charlie from wmass
    Charlie from wmass Member Posts: 4,253
    No worries about supporting the meter

    the gas company will most likely require it moved out of the basement if it is a Columbia gas customer
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • SteamInMA
    SteamInMA Member Posts: 7
    National Grid

    We're not Columbia, but National Grid. So far, nobody has mentioned a need to relocate the gas meter. Why would that be required?
  • RobG
    RobG Member Posts: 1,850
    Gas meter

    Two reasons, access and liability.
  • j a_2
    j a_2 Member Posts: 1,801
    meters in my area

    If the gas company has to replace the meter, up size the riser, or service, and the meter/meters are inside,they, if not already relocate them to within ten feet of service coming in….I was informed that was for them and the fire department….Makes sense to me…I can tell you, the inside fit is on the owner/owners…This is just in my area…Hope that helps….FYI add up the total btus required convert it cu/ft and see if the meter is sized correctly….The local gas supplier will tell you the but content of the gas…rule of thumb 1k btus per cu/ft of gas…..Example 100000 BTU BOILER 45000 BTU WATER HEATER 35000 BTU DRYER 65000 BTU STOVE EQUALS 245000 SO NOW A 250 METER IS OK…NOW ADD A FIRPLACE AT 15000 BTUS YOU NEED THE NEXT SIZE UP….Once again this is how it works in Boston metro are with the grid…Science don’t change but policy does
  • SteamInMA
    SteamInMA Member Posts: 7
    Update from OP

    Quick update - I haven't found any installers willing to do a gas burner conversion (none from the "Find a Contractor page" within 75 miles and several others from other references declined).

    About 20% of the plumbers have told me there are no near boiler piping issues even when I ask specifically about things that I know are wrong (including some of the plumbers on the "Find a Contractor page" on this site).

    Many others have either been no-shows or had ridiculous requirements (100% payment up front including all labor costs before starting the job).

    While I appreciate the advice I've received here, amazingly, it looks like sticking with an incorrectly piped oil fired steam boiler (with a HW coil!)  is actually going to be the most economical option. Never would have thought it....

    I even had one of those contractors from this site (who told me there

    were no near boiler piping issues that need to be fixed) tell me that

    there were no rebates currently in place with our local gas company or

    Mass Save because it is steam. Of course this is wrong and after i showed him the form, he admitted as much, but seriously these are heating and steam specialists this site refers people to?

    I strongly suggest that Dan re-vets the people he refers on this site. The reference material, advice, and resources are great. But the referrals are absolutely awful.