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  1. #1
    Join Date
    Feb 2005
    Posts
    6
    I am looking at replaceing an oldish Trane thermostat that has been destroyed. This should be a fairly simple operation, but the unit doesn't go by the normal wiring codes. All I have are numbers 1-7, and they didn't go by color codes either(orange is 24v hot?) Can anybody tell me what the numbers go to so that I can tranfer them into the standard RH, RC, W, G...etc? I've looked everywhere for a schematic and all I could find was a Lennox product sheet.

    Tstat is a Trane baysens0119a
    Unit is a Trane ych1b0b3h0dd

    Lennox part number 75H20 (seems to same exact tstat)
    Link: http://pirl.lennox.com/C03e7o14l/eRS...tstat_0993.pdf


    Thanks in advance, any help is much appreciated!

  2. #2
    Join Date
    Feb 2005
    Location
    Where it's dark & damp
    Posts
    609
    Trane packaged equipment does't use a conventional thermostat. They are actually sensors and can't be replaced with a conventional thermostat with out an optional circuit board in the unit called a conventional thermostat interface to give you the standard thermstat conections. As far as the conections terminal 1 is a zone temperature sensor, 3 is a setpoint potentiometer and 2 is common between the two. The rest are for the functions in the programable stat. They are a Trane only item. The sensor actually doesn't controll the unit as a thermostat does it only reports the room conditions to the unit and the unit does it own decision making. If you need to get the unit up in a jam there is an outside air sensor located in the condensing section. If you remove this sensor and install it accross terminals 1&2 the unit will run with a default stpt of 74 for cooling and 70 for heating. By removing the OA sensor you are disabling the economizer and low ambiant functions of the unit so its only an emergeny option. If you have the sensor you mentioned the unit is obviously not on a control system. As far as the basic temp sensor for terminals 1&2 it is a 10k type 2 thermistor.

  3. #3
    Join Date
    Jan 2005
    Location
    steeler nation
    Posts
    2,105
    buy or aquire the voyager book from your trane dealer. it has a ton of info on troubleshooting these units down to board components. you (I) need to have it to solve tough problems with these units. its one of the better service manuals i have seen.

  4. #4
    that book is called the Voyage continues and it used to be in pdf on this board. One link is http://www.westernairsystems.com/downloads/ go down to the voyager microprocessor link.


  5. #5
    Join Date
    Feb 2005
    Posts
    6
    Thanks, I was hoping to aviod a service call for something simple like that but it couldn't be avoided. With the info you guys gave me I was able to get the unit running until the contractor could make it out, I'm a sound engineer so I know my way around electronics.


    Another slightly-related question: The unit has two outdoor fans but only one runs when cooling. I asked the contractor and he said it was normal, that they both should run when the summer comes. I know what a two stage system is, and I know only one compressor is running, but shouldn't both fans be running?

    It's been a warm winter here, one week it's 65 out and the next it's snowing. Im sure the equipment is loving it.

  6. #6
    Hey Will,

    Do you know where i can get more info on that "conventional thermostat interface" you mentioned??? I have a Trane heat-pump I need to take control of, and I've been pokin' around on the net looking for one of those add ons.

    aTdHvAaNnKcSe

  7. #7
    Join Date
    Jun 2004
    Location
    Richmond Virginia
    Posts
    1,078
    Originally posted by controls_tech
    Hey Will,

    Do you know where i can get more info on that "conventional thermostat interface" you mentioned??? I have a Trane heat-pump I need to take control of, and I've been pokin' around on the net looking for one of those add ons.

    aTdHvAaNnKcSe
    The CTI as it is commonly called mounts to the right of the UCP board and connects with just a couple of pin connector strips to the UCP. The numbered designations will then become 24 VAC just like a conventional thermostat with some minor differences. I think the "contacts" are triacs so they act a little different. I do know that if heat and cool are accidentally called for together because of a humidity setup or nicked wire the unit will run neither mode rather than both as it is confused about what to do.

  8. #8
    Join Date
    May 2006
    Posts
    675

    Have you replaced the Stat

    Hello,

    I have the same problem in which I have a trane unit with a UCP board. The stat is the same and I would like to replace it with a conventional type which supports LON. Did you ever get it going with a conventional type stat?


    Thanks

    Clinton

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