"David Bono" wrote in message
...
According to the installation instructions, the Chronotherm IV should work
with the existing 2-wire system.

It will

Since the existing thermostat doesn't have a separate G terminal, I assume
the furnace takes care of turning the fan on and off.

It does to a point

What if the system doesn't have the G and X wires? Does that mean I can't
use this thermostat?

Like I said... you will need to ADD 2 more wires to get the Chronotherm to
work *correctly*

"Noon-Air" wrote in message
...
To get the Chronotherm IV to work correctly, you will need to run 2 more
wires
they will need to be wired as follows;
R - 24V
W - heat
G - fan
X - common

Then you will need to do the initial installer programming on the stat,
and
then program it for your personal comfort and times

"David Bono" wrote in message
...
I'm planning to replace my old mechanical White-Rodgers thermostat
(model
1C30-302) with a Honeywell Chronotherm IV.

My house has gas heat only, and uses a 24-volt 2-wire system (white
and
red
wire). This should be an easy DIY job, but I found the labeling on
the
old
thermostat confusing.

The old sub-base has 2 connections: one is labeled "4" (connected to
the
red
wire), and the other is labeled "R5" (connected to the white wire).

I know I need to connect these to the "R" and "W" terminals on the new
thermostat. Unfortunately, the terminal cross-reference for the new
stat
don't mention an R5 terminal. So, I don't know which wire should go
to
which terminal on the Honeywell.

I suspect since it's just a 2-wire system, it doesn't really matter
which
wire goes to which terminal (as long as I connect to the R and W). My
guess
is that the thermostat just makes/breaks the connection between R and
W
when
the stat calls for heat.

Should I just hook the Red wire to R, and the white wire to W?

Thanks,
David Bono