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Wiring Truesteam Humidifier to Oil burning Furnace

MG_74 Member Posts: 2
Problem.  We have a relatively new oil burning furnace and we are trying to install Honeywell Truesteam humidifier.  We have had to put in a White Rodgers 8A05A-101 fan center transformer to allow furnace blower operation independent of heating.  We have done that  and put in a new Honeywell thermostat.  We have the blower operating via new thermostat.  All of that is fine.  Still having trouble with the Truesteam not working.  No warning lights flashing.  Not sure if we have it wired properly to fan center?  Truesteam does not seem to recognize power from from HVAC?   Do we need a current sensing relay?


  • Mac_R
    Mac_R Member Posts: 117
    This should help

    Low-Voltage Terminals

    24V AC power for electronic humidistat.

    HUM Low-voltage humidistat (or thermostat) terminals control humidifier operation.

    C, R Connects to HVAC system transformer terminals (or relay transformer fan control R and C) to ensure HVAC power is present before humidifying. This can be disabled by changing DIP switch 4 (see page 16).

    RT Connects to thermostat R terminal, which is normally switched to call for fan.

    GT, GT connects to thermostat G terminal. GF connects to fan board G terminal. Thermostat G passes through the normally-closed (NC) relay contacts to GF, allowing fan activation. When TrueSTEAM is ready to provide humidity to the home, it will take control of the fan by forcing power from RT to GF (if not already activated).

    EXT When a 24-vac fan board is not used to control blower (hydronic or cooling-only applications), this connection with GF provides dry-contact closure for fan calls. EXT/GF may be wired to a low-voltage relay control center to provide line-voltage fan control.

    H and H go to your humidistat

    R goes to R on your fan center

    G on your fan center goes to GF

    GT goes to the G on the thermostat

    Then just hook up the transformer 24V to the 24V terminals.  There you go.  Good luck.  Don't forget to push the reset button to ready the device. 
  • MG_74
    MG_74 Member Posts: 2
    What about C?

    Thanks for the post.  I have had to wire in the fan center based on the wiring diagram that was provided.  It called for wiring the two original 24v T T wires to the R and W conneciton on the new Honeywell t-stat we purchased.  The fan center has a Com connection  which I have  assumed to be C which has been wired to C on the Truesteam and then another wired running from Com on fan center to C on thermostat. I think I have done the right thing.   As for power to the fan center.  It performs as a transformer as well and it is wired on its "hot" side to the power supply for furnace.  The other "side' of the fan center is 24V with R,C (Com), G, W and Y.   Are you saying I should wire 24V service to Truesteam from the fan center? 
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