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Wiring for V155A52C9 for new Nest thermastat

I own a 1929 house with a gravity gas furnace.
When I first moved in in 2002 I changed the thermostat to a digital thermostat.
I recently purchased a Nest Learning thermastat with hope that if my job doesn't get eliminated I will
have a new furnace installed in a few years.
My problem is that my honeywell digital had 3 wires connected to it.
The black wire was connected to W, the white wire was connected to R and the red wire was connected to B.
I am not sure if B was the right connection bit my furnace worked.
Yesterday I pulled the valve cover so that I could swap the old thermostat wires with new.
Any help would be appreciated.


  • ch4man
    ch4man Member Posts: 288
    that valve is a series 10, 3 wire control. best to call nest to see if its even compatible.
    your trying to install fuel injection on a model A- IMHO your not going to gain a thing.
  • Tim McElwain
    Tim McElwain Member Posts: 4,554
    That is a system that needs a DPST thermostat I am not sure if NEST can do that. However when we used to replace the
    Series 10 (DPST) with Series 80 (SPST) (two wire we would drop the RED (R).
  • ch4man
    ch4man Member Posts: 288
    edited December 2019
    yep. shed the red, was the saying i remember.
    but then the Nest will still need to find a common from the same transformer to be reliable.
  • Jamie Hall
    Jamie Hall Member Posts: 20,433
    I like the fuel injection on a Model A! And the Nest will not play well with the gravity system, no matter how you wire it. If I were you I'd wait to swap thermostats until I was able to do the new boiler and all the associated piping, and see what the state of the art is then.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Brianfromsyr
    Brianfromsyr Member Posts: 3
    Thank you all for your comments.
    The reason that I wanted a thermostat was the current one was failing me .
    I used to travel for work and during that time the batteries in the current thermostat had corroded. After rebate from my provider the Nest Learning cost me $99.
    I did buy a 24volt transformer with instructions if needed.
    Since then after cleaning the battery contacts I have had issues with the digital display coming and going.
    My previous job I serviced nuke plants.
    I knew nothing of the basics of home furnaces so this site was very helpful.
    It just gives me pause that there is no stamped label on this series 10 gas valve that allows me to verify my red wire or any other wire is where it should be .
    So I can check continuity when I get home to find out where the not conforming to thermostat label colors of my wires are going on the valve.
    The thermostat wire currently is just long enough to barely poke out of the drywall.
  • Brianfromsyr
    Brianfromsyr Member Posts: 3