Thermostat recently broke. Been nigger rigging it by touching

>>917583
https://nest.com/widget/compatibility/

>>917583
Depends on your heating unit. The easiest thing would be to run a new wire with 3 conductors. I'm pretty sure all wifi thermostats require a common as the power requirements are greater and a battery isn't enough.

>>917597
>I'm pretty sure all wifi thermostats require a common


Don't believe Nest when they say you do not need a common.

My AC works fine without a common, but I needed ta common for heat.

>>917599
Wait, whut?

How was it working before, then?

>>917601
Thermostats don't need a common if they are A) Mechanical/Mercury B) Electronic but take batteries

>>917597
>I'm pretty sure all wifi thermostats require a common

not necessarily. when the thermostat is off, it has 12 or 24V across it, which means it can use some of the available power to charge a local battery. it just needs to make sure it doesnt take enough current to activate the relay that it's controlling.

>>917636
Yeah thats how the Nest works. It has a built in Li+ battery that charges that way. Unfortunately it doesn't always work right and it would suck to buy a $250 thermostat only to find its running your AC at random times because its trying to charge its battery.

Its a good idea but not as reliable a solution as one might like. Running a new wire to include a common isn't usually too bad and is a much better solution.

Also, check if the existing wire has any unused conductors maybe pushed back into the wall or cut off that you could use as a common. I typically run more wires than I need for thermostats.

Update, bought the nest. Working good 260 later