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Hydrolevel

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Manofsteam
Manofsteam Member Posts: 11
in Gas Heating

have a Burnham IN7 steam boiler with a 24-volt control system and the factory-installed McDonnell & Miller 801-120 low-water cutoff. I’m installing a Hydrolevel VXT automatic water feeder. The VXT has power, but I need to know exactly which terminal on the factory 801-120 should provide the signal to the VXT FEED terminal when the boiler is in a low-water condition.

My 801-120 has only one C terminal. Which terminal/wire should I use to trigger the VXT feeder? Could you please provide the correct wiring diagram for this setup?

Comments

  • Manofsteam
    Manofsteam Member Posts: 11

    I sent this to Macdonald Miller .

    At no time do I get power at terminal c to trigger the feeder , there is no jumper in the 801

  • Steamhead
    Steamhead Member Posts: 18,851

    https://controlssupplychain.com/wp-content/uploads/manuals_pdf/mcdonnel-miller/CSC-mm-Uni-Match.pdf

    Co-Founder, All Steamed Up, Inc.

    Baltimore, MD, USA

  • 109A_5
    109A_5 Member Posts: 4,405

    I suspect the W terminal of the 801-120 goes to the Feed terminal of the VXT.

    image.png

    Similar to this. The C terminal on the 801-120 may not be the C wire with respect to the boiler's wiring. It is more likely the Common terminal of the relay inside the 801-120.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • 109A_5
    109A_5 Member Posts: 4,405
    edited 1:12AM

    A picture of the board and wiring to your LWCO may help. Are the screw terminals used or the connector like this ?

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,968
    edited 1:05AM

    Hot goes to H . N is your Neutral. You need a jumper from H to C if the factory jumper is missing. The burner gets wired to terminal B. The water feeder gets wired to terminal W.

    You also need a neutral to the burner and to the water feeder.

    The voltage of the water feeder needs to match the voltage hooked to H & N

    And make sure any other safety controls are wired in and ar working.

  • 109A_5
    109A_5 Member Posts: 4,405

    I'd careful with the jumper thing. If boiler works normally without it. Installing it may do damage. I don't see it illustrated in this version of the Burnham IN7 steam boiler manual. Although the electrical functionality seems present.

    Who knows what changes were made, possibly the Hot and Neutral are actually 120 VAC and the relay contacts are controlling 24 VAC so the isolation is needed (No Jumper). Pictures of the actual equipment would help.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System

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