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OLD (1986) 36c84-209 crossover

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Mole4x4
Mole4x4 Member Posts: 2
in Gas Heating

Replacing that valve - per SupplyHouse.com they said 36c84-912 was a direct plug and play match. the 209 fires right up but only .5"wc - so weak. 912 lights pilot, but main doesn't open. Has same terminals, same 3-prong (one larger) w/ matching numbers - all looks good except mgv not opening. Bad valve? Sure wouldn't think any re-wiring should be done, but dunno.

Help is surely appreciated. And, don't have model/s# - tags are unreadable, but since 209 'works' I only need a direct plug and play match. TIA

Mike

Red Stripe Service Company

Comments

  • Steamhead
    Steamhead Member Posts: 18,553

    What pipe size? Can you see the BTUH input rating?

    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Mole4x4
    Mole4x4 Member Posts: 2

    Just curious why you would need to know that - I can check. But, my question is: is the 912 a direct plug and play replacement as far as no different wiring needed? BTU of the 912 is correct. The main valve in the 912 not opening.

  • 109A_5
    109A_5 Member Posts: 4,122

    Looks like the 209 vs. the 912 is the pipe size.

    Is the inlet pressure good ?

    image.png image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    GGross
  • mattmia2
    mattmia2 Member Posts: 16,946

    need to set it up with a manometer and combustion analyzer, replacing a gas valve isn't a diy job.

  • mattmia2
    mattmia2 Member Posts: 16,946

    why did you replace it in the first place? if there is an inlet pressure problem it may lock out altogether.

  • 109A_5
    109A_5 Member Posts: 4,122
    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Jamie Hall
    Jamie Hall Member Posts: 27,425

    Sounds to me like a gas pressure problem, not a valve problem.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    mattmia2
  • Steamhead
    Steamhead Member Posts: 18,553
    https://forum.heatinghelp.com/discussion/comment/1895282#Comment_1895282

    In case the cross-reference was wrong, this would tell us what we're looking for.

    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • pedmec
    pedmec Member Posts: 1,410

    Sounds like you need a mercury flame sensor

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,336
    edited 1:43AM

    I refer you to the question I would ask the technicians that worked for me. It happens to be my signature tag line just below this comment.

    I had two customers with that gas valve / mercury flame sensor set up. I seem to remember that the three prong Mercury Flame Sensor (MFS) was something that I replaced often on both customers. It seems that the original lasted 30+ years but the replacement MFS were problematic and didn't last very long. I actually remember that one of the MFS failes within one year and the place I purchased it honored the 1 year warranty. they were affiliated with Johnstone Supply at the time so the main office had a policy for that warranty. Today that store is a mom and pop supply house because they didn't have a large enough property to provide the minimum amount of floor / warehouse space and they only had street parking. Bye Bye Johnstone. Hello American Parts co.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    mattmia2

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