HVAC - Thermostat wiring

[jrobie79]

Any HVAC guys in here? I have an old mercury thermostat. Flair 3 wire SPDT an I want to hook up this LUX programmable thermostat. Everything including the manual says the existing is usually lettered, but the Flair one is numbered - red - 4, white - 5, & green - 6.

I'm thinking I put the RED wire to one of the jumpered "R" terminals on the new thermostat, the WHITE wire to the "W" terminal and the GREEN wire to the "G" terminal. Correct?

[fight4life28]

Interesting, I do construction as my job and life for past 6 years. I normally don't do much HVAC Changes never the less one that old of setup to much newer setup, I would go with what you have down, The colors and numbers are very much same when I have seen or swap or moved setups before. Most of Thermostat wiring is color matched. Red, White,etc When I have install them. Your is very simple since there are only three connections.

Good luck and let us know.

[flyboyx]

is this thermostat also going to be controlling heat? looks like you probably have a fairly old house?

i would take the panel off the furnace and verify that the right color wires go to the right places. you never know what someone has done previously. inside the panel on your furnace there should be a wiring diagram. assuming you are doing both heat and a/c, you will need to hook up 5+ wires i think.

[AndrewBird]

^^^What he said. Check the furnace to confirm wiring.

[MR E30 325is]

With Flyboyx on this one.

[varg]

There is a standard wiring configuration, I don't remember it off of the top of my head though. There should be a wiring diagram or sticker on the transformer cover in your air handler or inside it, unless some dopey AC tech lost it.

[flyboyx]

here is a link to "thermostat wiring for dummies"

http://www.thermostatcenter.com/thermostat-wiring/

not saying you are a dummy, but it should be pretty easy to follow.

if you need more info, just google thermostat wiring.

[jrobie79]

I have, nothing about numbers...

here's the rest of the equipment, zone valve & boiler connections

[flyboyx]

yikes. old skool fo sho.

i remember when i was in hvac school, i helped one of my dad's friends with a house that had equipment like that. its been too long and i just don't remember. try googling something like "thermostat wiring with boiler" or hot water heat or hot water zone heat.

its a complicated one you have there. it can be done though. it might be a matter of dumbing down the thermostat to match what you are trying to hook it to. it may get to the point where it defeats the purpose of what you are trying to do.

[jrobie79]

yikes. old skool fo sho.

i remember when i was in hvac school, i helped one of my dad's friends with a house that had equipment like that. its been too long and i just don't remember. try googling something like "thermostat wiring with boiler" or hot water heat or hot water zone heat.

its a complicated one you have there. it can be done though. it might be a matter of dumbing down the thermostat to match what you are trying to hook it to. it may get to the point where it defeats the purpose of what you are trying to do.

someone on another DIY forum suggested:

4 = open --> W1
5 = common --> Rh
6 = close --> A

I'm thinking that might be the correct way. There were other responses, but some one said it can't work because the new t-stat needs a "C" wire...which is 100% does not, and says it explicitly in the manual, so I disregarded his post.

[jrobie79]

new monkey wrench (damn you amazon) the actual thermostat is model # TX500Uc, however it its a TX9100U package (I did buy it through Amazon warehouse deals, so it was in an open package)....unbelievable