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Wiring Honeywell RTH9580 WI-FI thermostat to Beckett 7505B Genisys burner control

bobshurt Member Posts: 5
edited February 2015 in Thermostats and Controls
I have a one year-old Peerless boiler fired by a Beckett burner with a 7505B Genisys burner control. This is supplying a 2-pipe steam system that the big, well-known local heating company totally *****d up when they did the install. I have a 330 gal tank that has to be refilled WEEKLY during the winter months. Fortunately, I found Charles Garrity (thanks to The Wall!) and things should be improving soon.

My immediate problem is simpler. I bought a Honeywell RTH9580 WI-FI thermostat and asked an electrician to install it. I was stymied by the fact that the WI-FI tstat needed a C wire feed that the old, battery-powered tstat didn't have. Unfortunately, the electrician was stymied, too. The Beckett 7505B Genisys burner control only has two terminals on it, labeled Tw and Tr, and the installation manual was no help. The electrician says he will have to install a separate 24v transformer to supply power to the WI-FI tstat. I find it surprising that the Beckett control doesn't have 24v to supply the tstat. These high-tech thermostats seem to be all the rage, and the instructuctions for the WI-FI tstat seem to assume that the burner control will supply it. Honeywell's automated internet support was no help. Is the separate transformer the only solution?

- Bob Simage


  • Abracadabra
    Abracadabra Member Posts: 1,948
    From the description, it sounds like not all versions have 24VAC.

    "The Beckett GeniSysTM Advanced Burner Control is a
    120 Vac primary safety control for residential and light
    commercial oil burners used in boiler, furnace, and
    water heater applications having firing rates less than
    20 GPH. The GeniSys is used with a suitable cad cell
    flame sensor to control the oil burner motor, igniter,
    and optional solenoid valve. It has 24 Vac thermostat
    terminals (if applicable) compatible with both mechanical
    and many power stealing thermostats.
  • Abracadabra
    Abracadabra Member Posts: 1,948
    After looking at the manual, doesn't really appear to be any points to pull 24V from control directly.

  • bobshurt
    bobshurt Member Posts: 5
    Oh, well, at least the electrician had a reason for being stumped! I'll try and contact Beckett tomorrow, but there is probably a 24v transformer in my future...
    - Thanks, guys
  • John Mills_5
    John Mills_5 Member Posts: 950
    There's a common there somewhere! Only trouble from what I see looking at a wiring diagram is they don't let you at it. I'm thinking you need a 51950U A/C adapter, that should give you a common. Unfortunately I can't find any wiring info on it but I suspect that will help you. Ask Beckett if you call them.
  • Mrwizard
    Mrwizard Member Posts: 3
    The Wi fi thermostat is designed to be wired with a dedicated common for continuous supply of power to the thermostat, as in the case of a furnace/fan center or ST9103 blower/burner control board. You will need to follow John's suggestion of an AC ready kit, Becket #51950U, a concept required by any oil primary with T-T/TR-TW terminals. It appears that it is not internally wired like a power robbing thermostat. Ask Honeywell if you can add a resistor as in their service bulletin MH4074FAB and eliminate the common.