Jeff Bulach wrote:
Hi,



I have just moved in to a 30-year-old house and I am having trouble
with the
thermostat. The original one is an old combined heat/AC rotatable
type.



I am replacing it with a new programmable one.



There is a blue Honeywell type box on the face of the furnace with a
terminating stripe down the side, what is its function. I suspect it
supplies low DC voltage, but not sure. I notice that the line for the
heating goes directly to the furnace igniter, should it not go to the
Honeywell box.



Any help or schematics would help.



Thanks.


Jeff,


Normally, thermostats work on 24 volts AC. W is heat(White); G (Green)
is the indoor blower; y (Yellow) is cooling or compressor; r (Red) is
24 volts hot; 24 volts common can be any other color, usually blue,
brown or black.

Heat pumps get a lot more complicated. Common is not used on many
older, non digital thermostats.

Stretch