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Honeywell WiFi thermostat RTH9580WF

Ross13 Member Posts: 4
-I posted this in oil heat.  I should have posted here.

I have a 2 zone oil heat system.  I currently have LuxPro thermostats.  The three wires coming out of the wall are the following:

RED - connected to RH

WHITE - connected to W

GREEN - NOT USED (not shown in picture)

BLACK - Jumped between RH & RC

The new Honeywell WIFI thermostat states you need a "C" wire for power.  I went down to the Burhnam furnace to check Honeywell board and the GREEN wire is not connected to anything.  I also do not see anywhere on the board a "C" to connect to?

Any suggestions.  Attached are 3 pictures. In order, Honeywell control board @ the furnace, current LuxPro t-stat, & the new Honeywell t-stat.


  • SWEI
    SWEI Member Posts: 7,356
    Which Burnham?

    The wiring diagram will shed light on this.
  • Ross13
    Ross13 Member Posts: 4
    Burnham Model

    Burnham model RS109T-TB  

    Manufactured in 1998
  • JStar
    JStar Member Posts: 2,752

    Install a switching relay with a Common terminal, ie: Honeywell R8845U.
  • Ross13
    Ross13 Member Posts: 4
    edited January 2014
    Switching relay

    Ok, so replace the existing panel with a new R8845U?

    Or I could always buy a Nest, which doesn't require a "C" wire, although I personally like the shape of the Honeywell vs. the round Nest.  I am not a heating guy so I will most likely hire a contractor to replace the relay if that is the only viable option, which it appears to be right now.

    Thanks for your help!
  • SWEI
    SWEI Member Posts: 7,356
    Can't make sense out of that number

    but it's probably a component ID of some sort.  From what I can tell, it was probably part of a V-74.  As I write this, Burnham appears to be in the midst of rolling out a major website update and I can't find the manuals I know were there as recently as last week.  A competent contractor could no doubt locate a common terminal in there someplace, but it's not something I could recommend you take on yourself.