[ho428]

We have digital but not programmable. Two story house. We've found the digital holds a more constant temp which on a two story seems to help keep them from fighting each other.
In Winter we have to set the downstairs 1-2 degrees below the upstairs or the hotter air going up the foyer keeps the upstairs furnace from coming on. By morning the upstairs bedrooms and bath would be pretty cold.
With the old style it was a lot harder to balance it. Now with digital just pick a number 1-2 below the upstairs and it's fine.

Next ones will be programmable though.

[JerseyGTO]

Unfortunately, this system is pretty much one big loop. I don't know what it would take to get two zones. I was just wondering how low I can turn it down when we're not home.

[GT182]

Pont406, do some reaserch on the Honeywell website first before you go out an buy one that's digital.

I thought we needed a new Tstat but didn't..... capactor in the furnace fan unit was cooked. Found that out after I went out and got a new digital Tstat at Home Depot. We had the old round type that controlled the heating and a/c. There are two red wires on ours.... one for heat and one for a/c.

The idiots at Home Depot said this is the one to get.... NOT. There are not enough terminals on this RTH2300B1012 unit. If you need a Tstat for 2 red wires like mine, you'll need a RTH221 type unit.... but check yours first to make sure.

[GT182]

Ok, went back to Home Depot today. My digital Tstat does not work. They did give me credit for a different one but it's not digital. It's just a regular round head non programable Tstat set up for the 4 wires.... 2 red, green and yellow. Part number CT87N on the back of the package.

After hooking it up, the only way heat will work is if the 2 red wires have the jumper hooked up. The bad thing is the heat won't shut off unless you disconnect the jumper. No idea what is freeking wrong with it.... it's hooked up as per the directions. A friend said most of the Tstats you get from Home Depot are junk... and I'm starting to believe him. So I'm off to someplace else tomorrow for another one.

Oh, these guys at Home Depot haven't a clue as to how the Tstats they sell are hooked up, and had no clue there are heating and cooling setups that use 4 wires for the Tstat.

BTW... the RTH2300 - RTH221 type units are no good for 4 wires. The most expensive ones they sell tho are for 4 wires. Go figure. LOL

[GT182]

Finally got my old mercury Tstat working. Plain red wire goes to white connection. Rh wire goes to Red and Rh connectors..... use jumper wire or connect Rh wire to both terminals.

So you know, this will be the same for a digital Tstat with heating and cooling. I assume heatpump will be different.

In attached photo for the mercury style Tstat, the R24v wire is jumped to the ON/Cool contact.