Question about dual thermostat configuration and power

[fgallina]

Hi Guys,

 

I've read quite a bit about thermostats in these forums, but I’m still unclear on this question I have – is it possible to operate a venstar dual-thermostat configuration where one thermostat is hooked up to the HVAC system, and the other one is just hooked to power, but is used to control the other thermostat? If so, how would I power the second thermostat? Thanks!

 

Frank

[oberkc]

I have no idea about the feasability of using one thermostat to control another.

 

Regarding power, most thermostats I have worked with are powered from the transformer at the HVAC unit, transmitted through two wires in the bundle to the thermostat unit. Assuming both thermostats are compatible with this power, would not using this power for both work?

[fgallina]

The issue I have is that my existing thermostat is downstairs and I want to add an additional thermostat upstairs. My house is over 100 years old, so extending those wires upstairs will require an electrician running a snake in the wall, cutting up the plaster walls, etc. If I can just pull power from a nearby outlet I can do it myself and minimize additional wiring and holes.

[oberkc]

I have no doubt that one could put together a transformer to power a thermostat. (I recall them being 24V.) How you go about communicating between the two is another issue. I have no direct experience with the venstar thermostats.

 

You may be interested in a new thermostat such as the one I have in my house...a honeywell prestige. It is a little expensive, but comes with a wireless remote control. The thermostat could be set to control your HVAC based on readings from the remote control.

 

Install the wall unit in place of your existing thermostat. Locate the remote control upstairs. No wiring. No mess. You may have to replace the batteries, however. It may be cheaper than running wires.

[Illusion]

Sure. No problem. Get a 24VAC transformer (like for a sprinkler system), wire it to R and C of the new upstairs T-Stat, plug it in, . Put Insteon adapters is both upstairs and downstairs t-stats. Create programs that use the conditions of the upstairs t-stat to make the down stairs t-stat do what you want. The possibilities are endless.

 

Of course, doing the remote idea of oberkc's will be much cheaper and may get you exactly what you want, but probably not easy to control with Insteon and tie into an Away setting.