[Skoda9]

I want to buy a programmible thermostat for a house I am doing over. I am using hot water rads for heating with no cooling. I will need two Thermostats to control 2 separate zones. How many wires do I need to pull to each thermostat for this set up. I am assuming 4 wires (two for the 24volt power and 2 for the contact on each)

[medic-dan]

You only need 2 wires to each thermostat.

Some thermostats take power from these wires by passing a small current through the system at all times. These are called "power-robbing." Other thermostats, including many newer Honeywell, use batteries.

You'll find that the installation instructions on most will expect only 2 wires for a typical, heat only install.

The problem with the battery models, and I have a thermostat with this warning, is that if the battery goes dead, the thermostat won't work and you have no heat. The display will show low battery though and they do last a long, 1+ years, time so don't worry about that either.

[hvacservicetech_07]

I agree with medic-Dan, two wires will be all you need. As for progamable thermostats, stay away from hunter or anything from walmart. Find a white-rodgers or honeywell. 1f87-361 is a very reliable thermostat. As for the wires you may want to pull an 18 4 or 5 just to be safe,if you ever need an extra wire or break one down the road you will have extra. Good luck!

[mygirlsdad77]

Agree with above anwers. However, if you are using a programmable thermostat, I suggest having at least three wires, so you can hook up the c (common) terminal to power stat even if batteries die. I deal mostly with honey well, and the instructions state that c is optional with batterys. But it is actually more like... batterys are optional with c terminal hooked up.

[hvac1000]

The cost of a good quality 5 or 7 wire thermostat cable is not much more than a 2 or 3 wire cable when you think of the advantages. There is always a future and with the future comes different ideas and sources of heat that might be cheaper or you may decide to add cooling or a heat pump system to your present system for comfort or energy savings.

Many times it is very difficult or almost impossible to run a new thermostat wire when the time for upgrades or different add ons come around so running it now saves much trouble in the future and also gives you a spare wire just in case something happens to the original wires being used to control your present system.

Good luck with your new system and post back if you have any hot water heat questions.

[Skoda9]

Thank guys,

I will definetely be going with a honeywell unit and a multiple wire conductor now that you have pointed out about future upgrades