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  1. #1

    Replacing Mercury Thermostat with Digital (Heat Pump System)

    We just bought a house. We have two zone heating and cooling (1st floor and 2nd floor). We have a newer Carrier system Model #213rna024 controlling the bottom floor and then a very old Trane System model #BWD724A100B0 running the top floor. In the house we have old Trane Mercury Thermostats (Baystat240 3AAT80B1A1).

    I want to replace these thermostats with something programmable and digital. I went to the store and was overwhelmed. I have no idea if i'm 5 stage heat pump, 4 stage heat pump etc. I bought some RiteTemp thermostats and had no idea how to hook them up because I have no clue what I have. Anyone have any ideas where to go here? Can you even have programmable thermostats with heat pumps?

  2. #2
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Not a DIY site. If you didn't know what you needed, and don't know how to connect them.... and can't figure it out after reading the instruction and diagrams... you're not qualified. And even then, jsut following the diagrams is bad because the previous installer may not have followed conventional wire colors. You have to know what terminal does what to know if it's conencted correctly.

    It's sad that when the new equipment was installed that modern thermostats weren't installed. The difference a good thermostat can make is impressive.

    Please call a pro who is qualified. Hooking it up incorrectly could cost you $$$ or $$$$ in repairs that equipment waranties won't cover.

  3. #3
    Join Date
    Jun 2009
    Location
    nashville, TN
    Posts
    18
    Sounds like you have to call an HVAC contractor. This is not a DIY site. It is agaisnt the site's rules to tell you how to install your tsat.
    Good luck!

  4. #4
    Quote Originally Posted by motoguy128 View Post
    Not a DIY site. If you didn't know what you needed, and don't know how to connect them.... and can't figure it out after reading the instruction and diagrams... you're not qualified. And even then, jsut following the diagrams is bad because the previous installer may not have followed conventional wire colors. You have to know what terminal does what to know if it's conencted correctly.

    It's sad that when the new equipment was installed that modern thermostats weren't installed. The difference a good thermostat can make is impressive.

    Please call a pro who is qualified. Hooking it up incorrectly could cost you $$$ or $$$$ in repairs that equipment waranties won't cover.
    Will any heating/cooling type company work? Is that what you mean by HVAC contractor? What do they typically run to install this type of stuff?

    Also does anyone know what my SEER rating is on that older unit?

  5. #5
    Join Date
    Jun 2009
    Location
    nashville, TN
    Posts
    18
    Quote Originally Posted by geissap View Post
    Will any heating/cooling type company work? Is that what you mean by HVAC contractor? What do they typically run to install this type of stuff?

    Also does anyone know what my SEER rating is on that older unit?
    Yes call a local reputable HVAC company. Pricing is not discussed in this site. The seer ratio depends on how old your system is, wear an tear, and maintenace history. You probably can find out the seer ratio when the machine was built by doing some resarch on the munufacturer's web site and have your model # handy.

  6. #6
    Join Date
    Aug 2008
    Posts
    24

    Be carefull with those old stats!

    If you do wind up replacing them yourself, be careful with those old t-stats. It is most likely illegal in your area to throw them in the trash (Mercury is toxic). If you have an HVAC contractor replace them, they will (required) take care of them.

  7. #7
    Join Date
    Jun 2009
    Location
    N.C.
    Posts
    16
    Definetly get a hvac repair man to replace those mercury and spring loaded thermostats. Their just to outdated,and not accurate. By the time the thermostat reaches the temperature, the unit has already ran 2-5 minutes past what it would with a plus or minus one degree thermostat.

  8. #8
    Join Date
    Sep 2002
    Posts
    12,568

    Good idea to replace them

    It's usually not a difficult job - But make no mistake: It Certainly Can Be

    As a 30 year contractor, I can tell you that whatever thermostat you find in a retail store is not what you really should have. It has been my experience that they are trash.

    A perfect example is what you bought. In my opinion what you already have is superior. Now I don't mean "good" <g> - just better that what you bought.

    When you say: a zoned system - what do you mean? Are there two, or more, independent systems? One system with duct dampers?

    Oh; and yes; there are programable thermostats available to control any sort of HVAC system you may have. But it's important to know both what you have, and then to properly apply and install the controls for what you have.

    PHM
    -------



    Quote Originally Posted by geissap View Post
    We just bought a house. We have two zone heating and cooling (1st floor and 2nd floor). We have a newer Carrier system Model #213rna024 controlling the bottom floor and then a very old Trane System model #BWD724A100B0 running the top floor. In the house we have old Trane Mercury Thermostats (Baystat240 3AAT80B1A1).

    I want to replace these thermostats with something programmable and digital. I went to the store and was overwhelmed. I have no idea if i'm 5 stage heat pump, 4 stage heat pump etc. I bought some RiteTemp thermostats and had no idea how to hook them up because I have no clue what I have. Anyone have any ideas where to go here? Can you even have programmable thermostats with heat pumps?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

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