[Srey]

I'm looking for help from labman or any experienced HVAC person... here goes...

I recently purchased 2 Honeywell Focus Pro 6000 programmable model TH6110D1005 thermostats (I have 2 zone heating). I'm a replacing a mechanical honeywell dial mercury thermostats (Probably about 20 years old or so). When I took the cover off the old thermostat, I noticed there were 4 different wires. There was a red, black, green and yellow. The red and back wires were connected together to the R terminal on the thermostat and the green and yellow wires are connected together to the W terminal. There is a Y terminal on the thermostat, but no wires connected to it. It is a heat only system and I do not believe that there is a fan. I also went to the boiler to look at the configuration and there are two boxes (I assume one for each zone) and each box has two terminals named T and each one has two wires connected to them (Red and Black together and green and yellow together)

The Focus Pro has G W C Y R Rc slots. There is a jumper between the R and Rc slots. I have hot water baseboard heating system with a boiler. It is heat only. I got confused with the red and black wires and green and yellow wires connected together. Any idea on how to hook up the new thermostat with that configuration. Do I leave the jumper in the R and Rc or do I remove it?

My first reaction was to connect the new tstat the same way as the old one with the red and black in the R terminal and green and yellow in the W terminal and leave the jumper in. But I am hesitant to do that because I don't want to scew anything up and have to get someone in to fix my error.

The instructions for the focus pro say to have a professional install this thermostat, but I also looked at the RTH6300B thermostat that say a DIYer can install it? What is the difference and should I return the Focus Pro and get the RTH6300B thermostat?

Any help would be greatly appreciated.

Thanks so much in advance,
Scott

[EPMiller]

It appears by your description that the two wires twisted together on each terminal is somebody's idea of fail proof. They probably also wear a belt with their suspenders. Also, that's telephone wire instead of tstat wire. Colors are the giveaway. There's nothing wrong with that if it is 18 or 20 gauge solid and not the light gauge flat station wire or stranded wire. Sounds like a plugger job.

First off, if it isn't as heavy gauge as normal tstat wire, you probably should replace it with the real thing unless the run is short. If it's the flat cheap station wire you will have problems down the line when the insulation degrades enough to short together. (I've seen it happen, fellow had to rewire his whole house telephone system.) Then wire it like your first reaction. The Rc and Rh don't make a difference in your application. Leave the jumper there. Of course you will need another tstat for the other zone.

You are using a sports car of a tstat in a situation where a Ford Escort would do, but the programming features are nice. Make certain that you get the installer program set up correctly, otherwise you should go get a more basic thermostat.