Honeywell Mercury Themostat 3 Wire, replace with Digital/Programmable
thermostat
Have an old Honeywell thermostat (house is 17 years old). Wondering if I can replace it with a newer Digital or Programmable one?
Here are some pictures of it.
Best Answer
What your options for replacement are (easily) depends on what your wiring is.
I find it odd that you claim it's getting inaccurate, but perhaps they built them better 50 years ago than 20 - all the 50-60 year old ones I have work as good as new, but those are the "classic round" version. They actually are subtly adjustable if needed, though non-subtle attempts can screw them up. They are sidelined at the moment, but in reserve in case of need.
Anyway, for a two wire setup the easy digital/programmable solution is to get a digital/programmable that uses batteries - I have a couple of examples of these in my view between home and work, and the older one eats batteries a lot slower than the newer one.
The fancy/expensive/prone to becoming obsolete so you need a new expensive - "Smart" thermostats (or hacking portals into your house) generally require a wire upgrade to supply the power they want. I'm obviously not a fan, but many people do seem to love them. Some of those people are not living in your house...
Check the wires on the terminal strip in your furnace they should be labeled, match the letters R-R W-W Y-Y G-G from the furnace to the thermostat and usually the colors should match also so: r-red g-green y-yellow and w-white.
Make a list of all the terminals, and the color of the wire that connects to each.
Rc - Red R - Jumper W - White
etc.
Next turn the breaker off for the furnace, and/or switch off the serviceman switch for the furnace. Then open the service panel on the furnace. You should be able to locate the control board where these wires connect, which should tell you everything you need to know.
Best Answer
What your options for replacement are (easily) depends on what your wiring is.
I find it odd that you claim it's getting inaccurate, but perhaps they built them better 50 years ago than 20 - all the 50-60 year old ones I have work as good as new, but those are the "classic round" version. They actually are subtly adjustable if needed, though non-subtle attempts can screw them up. They are sidelined at the moment, but in reserve in case of need.
Anyway, for a two wire setup the easy digital/programmable solution is to get a digital/programmable that uses batteries - I have a couple of examples of these in my view between home and work, and the older one eats batteries a lot slower than the newer one.
The fancy/expensive/prone to becoming obsolete so you need a new expensive - "Smart" thermostats (or hacking portals into your house) generally require a wire upgrade to supply the power they want. I'm obviously not a fan, but many people do seem to love them. Some of those people are not living in your house...