The bedrooms in my condominium looks something like this:

enter image description here

A common HVAC unit provides heat and air conditioning between bedrooms, with the thermostat being in the Master BR.


Bedroom 2 loses heat far faster than the Master, due to having more windows, and this goes undetected by the thermostat.

The current solutions are to either:

  1. Overheat the MBR to keep the 2nd BR livable, or
  2. Put a space heater in the 2nd BR.

Currently we've been doing #2, but it's a kludge and we're looking for something better. Is there a way to add a slave thermostat, preferrably wireless, in the second bedroom so the system knows the room is getting too cold?


  • The unit uses Honeywell T6570 or T8570 thermostats (Datasheet Here). I can't tell which without detaching one from the wall.

  • The unit is rented so we cannot make drastic/irreversible changes.

  • Where's the thermostat now? You could almost certainly put two in parallel, so that if either is low the heat comes on. Of course that does risk overheating the other room... Or you could just relicate the thermostat. Or you could do fancy radio thermostat things, but it sounds like that would be overkill... – keshlam Dec 31 '15 at 6:08
  • I honestly think that #2 is the right way to do it, and #1 is a inefficient kludge. This is really what larger space heaters are made for. – JPhi1618 Dec 31 '15 at 15:18

Placing a second parallel thermostat or moving the single thermostat to the colder room will not be an ideal solution for you. The reason being is that the second room will call for more heat and indeed warm up but the master room will get overheated.

The proper way to fix this is to re-balance the heat registers (or duct deflectors if they are present) to allow less warm air to enter the master room and proportionally more to enter the second room.

| improve this answer | |
  • Agreed, but this will also cause a larger temperature "swing" in the second room as it heats up faster than the master because of the extra air, and then cools off faster because of all the windows. – JPhi1618 Dec 31 '15 at 15:21

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