Can a programmable thermostat be hooked up to a old furnace and ac unit
October 13, 2013 10:31 AM   Subscribe

My mother-in-law has a old furnace in her basement and a air conditioner unit outside, can these be hooked up to one of those new programmable thermostats?
posted by just asking to Home & Garden (8 answers total)
The thermostat tells a furnace or air conditioner when to go on and stop, so a programmable thermostat should be fine. I've had older gas and oil furnaces, and have used programmable thermostats with no trouble. If the A/C is run by a wall thermostat, it should work. I haven't seen a window unit work with one, though.
posted by theora55 at 11:03 AM on October 13, 2013 [1 favorite]

Don't know about the A/C but we have one for our OLD oil furnace. Works just fine.
posted by michellenoel at 11:05 AM on October 13, 2013 [1 favorite]

Pull the cover off your current thermostat and see how it is wired. There will be various labels next to the wire connections. Take a photo of the wiring, or write down the names of the labels.

Go to the manufacturer's website for the new programmable thermostat you're interested in. If they have a compatibility tester, you can check with that.

Alternatively, go to the support section of the website and download the manual for the thermostat you're interested in. Check with the manual to see if the wiring you have is supported by the thermostat.
posted by Blazecock Pileon at 11:05 AM on October 13, 2013 [2 favorites]

I recently went to the "contact us" part of Honeywell's website. I indicated what I wanted from a new programmable thermostat and told them a bit about the present system.
They wrote back with a few questions, and ultimately recommended a device that met my needs.
They were prompt and responsive and helped me avoid purchasing items that would not have been suitable for the situation.
posted by elf27 at 11:37 AM on October 13, 2013

Almost certainly yes.
posted by zippy at 11:40 AM on October 13, 2013

Most likely. I have a Nest second-gen and a 19-year-old gas furnace and they get along just fine.
posted by bizwank at 12:20 PM on October 13, 2013

Do the current systems operate off the same thermostat? One of the reasons I've avoided the Nest is because I have separate heating and A/C systems (boiler for radiators in most of the house, controlled by a first-floor thermostat; baseboard heating in an addition, controlled by thermostats in each room; and a SpacePak high-velocity A/C controlled by its own second-floor thermostat) and, while the system supports multiple units, that just seems more daunting.
posted by subgenius at 1:47 PM on October 13, 2013

If Nest is the programmable thermostat you're considering, get in touch with them directly!

My mom wasn't sure if a Nest would work with the heat and AC in her old house, and they had her send a photo of the current thermostat wiring to their customer service, and advised her. After she hooked it up, she sent a second photo and they verified that it was all hooked up correctly. They are really, really helpful.
posted by duien at 4:29 PM on October 13, 2013

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