On Tue, 10 Sep 2013 04:58:30 -0400, Don Wiss
wrote:

On Mon, 09 Sep 2013 20:37:58 -0700, Tony Hwang wrote:

bob wrote:
I want to put in a smarter thermostat that requires power supplied by
the furnace. This requires more wires. I'm thinking of pulling out the
old wire and put in new thermostat wire. I think the maximum I can get
is 8-wire. Is it advisable to do this or is 5-wire sufficient? The
8-wire will be harder to pull/fish.

You'll have spare wires then. If you don't use a/c, 4 wire is needed.
Or forget the wire all together and go wireless. I did that and we can
move thermostat to any spot in the house.

Wireless may be fine for now, but if you switch to a high end system like
Carrier's top-of-the-line Infinity, you have to use their wired thermostat
that goes with the system.

That's good to know. I'll avoid Carrier like the plague.

The communication between units is computerized. It does not use a lot of
wires. Five will be enough. Shielded could be a bonus in an electrically
noisy environment.

A shield is superfluous. Five may not be enough, depending on the
system. I believe mine has 8 (not all are used, currently).