Ask Experts Questions for FREE Help !
Ask
    drummerbear26's Avatar
    drummerbear26 Posts: 1, Reputation: 1
    New Member
     
    #1

    Oct 24, 2007, 12:18 PM
    Replacing Lennox Thermostat with Honeywell Thermostat
    I have a Lennox T90H110A137 Thermostat with the following terminal letters and wire colors:

    G - blue wire
    F - red wire
    C - green wire
    H - yellow wire
    V - white wire

    I want to install a Honeywell RTH6300B Thermostat. According to the RTH6300B Installation guide, it tells me to ignore wire color and only use the letter designations. The Installation guide has these letter designations:

    G
    W/OB
    NOT USED
    Y
    R
    Rc

    It further says to use this chart if the labels do not match up:

    C or X B - Do Not Connect
    G or F
    W or W1 H O B
    Y or Y1 M
    R or RH 4 V
    Rc or R

    Given that information, I have been able to match all but one wire up:
    C=C - Do Not Connect
    G=G
    R=V
    W=H

    My question is, given that the Lennox has both G and F and the Installation Guide says G or F, am I suppose to hook both G and F to the G terminal or just the G wire to the G terminal?

    Thanks in advance for your help
    JasonHoldenCO's Avatar
    JasonHoldenCO Posts: 2, Reputation: 1
    New Member
     
    #2

    Jan 29, 2010, 05:38 PM
    Did you ever figure this out? I have the same question.
    cdquikmc's Avatar
    cdquikmc Posts: 2, Reputation: 1
    New Member
     
    #3

    Mar 8, 2015, 07:19 PM
    T-90H110A137
    I know this post is old, but I just replaced this same unit successfully, so I figured I'd get some karma out of it and make it easy for anyone else looking.


    Just to clarify, it's an ITT General Controls" thermostat, model T-90H110A137, 24 volts max, 0.8 AMP. I have a forced air heat and cooling system, which is also Lennox.


    The main issue is the letters/labeling for each terminal does match "modern" standards. In addition, my wiring did match the colors either, so it was a combination of research and guesswork to get it to work. (Two disclosures: I'm not a professional as this is the first thermostat I've replaced and I changed this is March, so I didn't run the A/C for long.)


    You can probably ignore the wire colors (in parentheses) but I included them just in case.
    Old Lennox - (Wire color) - New Thermostat - [Function/what it does]
    G - (Orange) - C - [Ground]
    F - (Blue) - G - [Fan]
    C - (White) - Y - [Cooling/Compressor]
    H - (Green) - W - [Heat]
    V - (Red) - RcRh - [Power/Voltage]


    Looking at the old labeling, it makes a lot more sense since the letters actual mean something.

Not your question? Ask your question View similar questions

 

Check out some similar questions!

Connect Honeywell Thermostat in place of old Lennox [ 2 Answers ]

I have a Lennox thermostat 67K4801 with numbers > and 3AAT89B38G1. > (Y1 G. O. R. L. T. C. W1. E.) I just purchased a Honeywell Programmabel to replace the old Lennox. The wiring instruction booklet shows all alternate wiring combination, except how to connect the T terminal. Please help! ...

Replacing old honeywell thermostat with new programmable [ 3 Answers ]

Hello, I am in the process of replacing an old honeywell thermostat (Q539A1014) that was installed by a HVAC prof. about two years ago. We wanted to upgrade to a programmable thermostat. We purchased a RTH6300B Honeywell. I was told by the home improvement store this was compatible and...

Replacing Honeywell thermostat [ 4 Answers ]

Hi, Thank you for your help in advance. Just bought a Honeywell programmable thermostat RTH7400 to replace an older Honeywell mercury thermostat (I think its model is Honeywell Heat Pump thermostat 8919) My old one had: G, Y, R, O, W2, X, E The manual's Alternate wiring scheme (for...

Replacing Janitrol Thermostat with Honeywell Thermostat [ 1 Answers ]

I am attempting to replace my manual Janitrol Model HPT 18-60 thermostat with a Honeywell Programmable Model CT3500 thermostat. My Heat Pump is a Trane TWR012-042C The 6 wires connected to the Janitrol thermostate are: Y, W2, G, R, O, C How do I connect these six wires to the Honeywell that...

Please Help w/Replacing Honeywell Thermostat... [ 3 Answers ]

Hi! I've just removed my Honeywell Thermostat and am trying to replace it with a Noma programmable tstat... but am having problems with the wiring. There are 5 wires coming out of the wall - Green, Black, Orange, Red and White, and only 4 posts on the Noma tstat (Green, Red, Yellow and White). ...


View more questions Search