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Converting from Oil to HE Gas - WM unit recommendation

Jaron Member Posts: 3
I'm in the final stages of planning my switch from my 50+ year old oil unit (it originally did coal then one of the previous owners put an oil burner in it) to a HE natrual gas unit. The contractor I want to work with - I have 2 personal references and he has the best prices - gave me quotes for weil-mclain units:

- GV90+4

- WM97 (+$1000)

- ultra105000 (+$1750)

I'm looking for opinions on these units. I was leaning towards the GV90 until I saw this thread (<a href="http://www.heatinghelp.com/forum-thread/146798/W-M-GV-90">http://www.heatinghelp.com/forum-thread/146798/W-M-GV-90</a>) so I thought I would just ask outright.

System wise, I have a small, single-zone home that I need to heat. The current system is gravity operated with copper radiators.

The ultra seams a little too pricey but I would consider it if the quality is there.



  • SWEI
    SWEI Member Posts: 7,356
    Did the contractor you want to work with

    perform a heat loss calculation?  How big is the house?  Where is it located?
  • Jaron
    Jaron Member Posts: 3

    If any of the 5 contractors did, they didn't share it with me. I doubt it was done as they didn't do all the room measurements to do so. Most of them approximated the heating need based on the existing burner and/or radiator load.

    My home is ~50 years old and is located 50mi northwest of Philadelphia, PA. I have already upgraded all of the windows and have good insulation in the attic. It's about 1300 sq ft of heated living space (not counting basement or attic.)
  • SWEI
    SWEI Member Posts: 7,356
    Heat loss

    really needs to be done before anything is sized, proposed, or priced.  At 1300 square feet, your house will need well under 50,000 BTU/hr (and quite likely less than 40,000) to heat it -- on the coldest day of the year.  The most important figure for mod/con boiler sizing will be the MINIMUM firing rate of the boiler.  The smaller this number, the happier the boiler (and you) will be.  I'd probably recommend either a Lochinvar WHN055 (11k minimum rate) or perhaps the CDN040 (9k minimum firing rate) for a job like this.  If you're set on Weil-McLain, I'd suggest looking at a WM 97+ 70 (14k minimum firing rate.)
  • Jaron
    Jaron Member Posts: 3

    Thanks SWEI for pointing me in the right direction!
  • Rich_49
    Rich_49 Member Posts: 2,738

    Swei's advice and have the heat loss done .  These contractors may have been referred by friends but that does not make them the guy to use . Since none did a heat loss that has been confirmed . 

       Of the units mentioned I could only recommend the WM97 . Don't much care for either of the others .  Being as you only have one zone you really want to make sure you get the smallest boiler capable of heating your load at design conditions and also one that will modulate down really low . Again , Swei's recommendation is good
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
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