Robertshaw TX400 and Mastertrol Mark V

[AlexD1]

Hi everyone, 

I moved into an older house in September with a 1989 HVAC system. 

Photos for this post are here: https://imgur.com/a/3Uob64C

Forgive me if I am using any of the wrong terminology. 

It has a "Mastertrol Mark V" control board

and has three old Robertshaw TX400 (I think) thermostats. See photos.

It's a three zone system each with it's own thermostat.

The system has a switch to flip between Off / Cool / Heat / Fan. Since it is winter in the Northeast it is set to Heat and working ok.

Can I use either of the Nest thermostats to control this? It's driving me nights that (1) there is no precision in control, (2) no away feature, and (3) no remote control capabilities

The TX400 appears to have 3 wires (see photo)

[zoeuvre]

Hi AlexD1, 

Thanks for posting here in the Community forum and for showing interest in our Nest Thermostats. Can you verify what terminal the white wire is connected to in your Robertshaw TX400 thermostat? You may also use our Compatibility Checker to determine if a Nest Thermostat is compatible with your heating and cooling system.
 

I'll look forward to your response. 

Best,

Zoe