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Thread: Honeywell Lyric T5 with G2 and G3 terminal

  1. #1
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    Honeywell Lyric T5 with G2 and G3 terminal

    Hello,




    First off - apologies if this question has been asked already in some form, and if so, please point me to the solution.

    I live in a rental condo unit that has the TB7100A1000 MultiPRO thermostat installed. The heating and cooling are centrally controlled at the building level. The wiring for this is in the attached image.
    Click image for larger version. 

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    I intended replacing this with a smart thermostat, and chose to go with the Lyric T5 since I figured this would have the least wiring issues, if any. I confirmed that I have the C wire - so should have been good to go, on the basis of which I bought the lyric T5.

    Upon trying to install it, I mapped the wires and everything else maps - but G2 and G3 do not map to anything on the Lyric. Looking at the manual, it appears that G, G2 and G3 are for low, medium and high fan speeds. I called Honeywell support, and they said that the Lyric cannot be used with my setup and suggested returning it, since it would not work. Before I give up and return it, I would be thankful if someone here could shed light on the following:

    1. - Is it possible to use the Lyric by connecting one of the G terminals and setting fan speed to AUTO? I know this would mean that I will not have multi-speed but just a on/off toggle. Would using it like this damage anything?
    2. - Interestingly, the back of the front panel where the circuit board is shows the following labelling, as attached. Looking at this, it appears Y2-E connects to G2 and L connects to G3 on the wall plate. I can see the Lyric has terminals for Y2, E and L/A. Does this mean I can connect G2 and G3 to these terminals on the Lyric, as that's how it was connected all this while anyway (judging by the circuit board labelling?)?
      Click image for larger version. 

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    Thank you in advance for any help or assistance with this!

  2. #2
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    You could just pick one of the speeds and connect fan wire to the G terminal at the Lyric. For your setup at the Lyric connect either the red, blue or brown wire the G terminal for the fan speed you want. The speed would depend on what type of HVAC you have. If you have a hot water chilled water system you should be fine with any speed it just may not be as efficient as selecting the most optimal speed. Typically the fan runs slower in the heating mode but it does depend on the type of HVAC system

  3. #3
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    Quote Originally Posted by Thermostat View Post
    You could just pick one of the speeds and connect fan wire to the G terminal at the Lyric. For your setup at the Lyric connect either the red, blue or brown wire the G terminal for the fan speed you want. The speed would depend on what type of HVAC you have. If you have a hot water chilled water system you should be fine with any speed it just may not be as efficient as selecting the most optimal speed. Typically the fan runs slower in the heating mode but it does depend on the type of HVAC system
    Thank you so much!
    I'll try that this weekend and let you know how it goes. On my current thermostat though, I only manually change speeds to 'HIGH' (so, G3) , or leave it on AUTO and it seems to be on 'LOW' (G) most of the time when this is the case. Following your advice, I will probably connect G3 on the old one to G on the Lyric, so I basically get almost the same functionality.

  4. #4
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    G/G1 (lowest fan speed) will probably meet your needs quite nicely in a condo. My system never activates G2 or G3 fan speeds unless there's a 7 degree temperature difference between current and desired temperature.

    A word of caution: you probably have a 2-pipe fan coil unit and the Honeywell TB7100A1000 uses special wiring. Open the cabinet under your thermostat and take a picture of the schematic if you'd like me to check this. I ran into the same setup issue. In my case, what was the "W" wire on my TB7100A1000 was actually an emergency/aux electric heater (more expensive/unnecessary to run).

    Quote Originally Posted by pr4sanna View Post
    Thank you so much!
    I'll try that this weekend and let you know how it goes. On my current thermostat though, I only manually change speeds to 'HIGH' (so, G3) , or leave it on AUTO and it seems to be on 'LOW' (G) most of the time when this is the case. Following your advice, I will probably connect G3 on the old one to G on the Lyric, so I basically get almost the same functionality.

  5. #5
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    Quote Originally Posted by lonjim2 View Post
    G/G1 (lowest fan speed) will probably meet your needs quite nicely in a condo. My system never activates G2 or G3 fan speeds unless there's a 7 degree temperature difference between current and desired temperature.

    A word of caution: you probably have a 2-pipe fan coil unit and the Honeywell TB7100A1000 uses special wiring. Open the cabinet under your thermostat and take a picture of the schematic if you'd like me to check this. I ran into the same setup issue. In my case, what was the "W" wire on my TB7100A1000 was actually an emergency/aux electric heater (more expensive/unnecessary to run).
    Thanks for your reply - I think I may have a 4 pipe Fan Coil Unit by Whalen, but you could be right, I'll check. I can confirm this later tonight. However, long story short, I returned the Lyric T5 and got the Ecobee 3 Lite instead. HoneyWell support actually told me that my configuration is not compatible and the 'HVAC system was not designed to be used this way' (without the variable fan speed). That was a big loss in confidence statement for me, coming from the HoneyWell guys themselves, so got the Ecobee 3 Lite instead, to avoid any risk (it's a rental unit). I will be installing it using the exact same wiring setup that was suggested in this thread, will report back on how that goes.
    Last edited by pr4sanna; 01-10-2017 at 02:45 PM. Reason: more info

  6. #6
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    Quote Originally Posted by pr4sanna View Post
    Thanks for your reply - I think I may have a 4 pipe Fan Coil Unit by Whalen, but you could be right, I'll check. I can confirm this later tonight. However, long story short, I returned the Lyric T5 and got the Ecobee 3 Lite instead. HoneyWell support actually told me that my configuration is not compatible and the 'HVAC system was not designed to be used this way' (without the variable fan speed). That was a big loss in confidence statement for me, coming from the HoneyWell guys themselves, so got the Ecobee 3 Lite instead, to avoid any risk (it's a rental unit). I will be installing it using the exact same wiring setup that was suggested in this thread, will report back on how that goes.
    Thanks so much for your help guys.

    I setup the Ecobee last night and everything went (mostly) well. The only issue was that my Y wire (for cooling, I believe) was not showing up as connected on the Ecobee, even though connected. This Y wire was also connected on my old thermostat. The heating is working perfectly fine.

    The Fan Coil unit in my apartment is not a Whalen, but this: https://engineered-comfort.com/produ...del-series-39l (Model E39 LZE). I rent in a condo that had people moving in only in December 2016, and I suspect they switch between heating and cooling depending on time of the year ( I live in Canada), so one possibility is that the cooling hasn't been centrally switched on at all.

    What I'm confused about is this - is my reasoning for the Y wire issue correct or is there something wrong with the Y wire? (which means the fan coil unit has to be opened). Is it a normal practice to centrally control it this way, or is my assumption completely illogical?

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