What to use for Thermostat wire?

[fredhargis]

I just remembered I need to run a wire to connect a future thermostat (not yet purchased) to a future furnace (ceiling hung Modine type, also not yet purchased) in my shop before any drywall work. This is a common heat on/off, low voltage, temperature control thermostat. I've installed 2 in the way past, but cannot remember what wire I ran. I know it's very thin (22 gauge?) but can't remember how many conductors are needed.  But I know most of you out there know, maybe you can remind me.

[tomsteve]

a roll of 18/5 should give ya enough conductors

[Mr_Mike]

More conductors than you think or in the next replacement, you'll be running new.

Go on-line and get the install instructions and use that many wires, at least.

[daddo]

You shouldn't need more than three wires for heating only. I only buy 3 and 6 wire but use the 6 in places where you may never be able to replace it just in case a wire gets chewed on by a rodent or for some reason opens.

[blackhat]

You need 2. R and W. 22 ga would but 18 is better. Running a 3 or 4 conductor just in case of a nail strike wouldn't hurt.

[fredhargis]

Thanks all, I'll pick up some 18 gauge 4 conductor.

[Roly]

Something else to think about is possibility using two thermostats for heating.    A low temp thermostat to keep from freezing and a timer on the high temp thermostat for when occupied.  We used this system for normally unoccupied control buildings.     Roly ( uses the same wire )

[blackhat]

I'm going to set up something similar with a motion sensor on the high temp stat. I need to get a time delay so it doesn't start when I walk through to drop trash in the can.

[Roly]

Something like THIS for a time delay.    Still need the motion detector part.  This will reset when it looses voltage.    Roly

[efmrrt]

Best thing is to look and see how many wires you have now. If your upgrading, how many wires will you need?  If you have an older Honeywell Merc Switch with older heater 2 wires. On some of the newer units if its heat and AC 4-5 wires may be enough. Go to the BORG and get thermostat wire with the number of wires needed 18 gauge/ # of wires inside, from 2-8.  Make sure you get more wire than you think you need. It sucks coming up short.