"William W. Plummer" wrote in message
news:UsCUb.182644$Rc4.1353160@attbi_s54...

"CBhvac" stephenaddressscfrewedonpurpose@carolinabreezehva c.com wrote in
message ...

"Doug" wrote in message
om...
We set our thermostat down to 63 at night, set to heat up to 70
(tropical, I know) starting at 6am. On most days everything works
normally. However, on occasion, I will come downstairs at 7:30 am and
find that the thermostat is reading only 61 degrees-- 2 degrees colder
than the coldest temperature, and 90 minutes after the heat was
supposed to come on!

The furnace appears to be working; the house does heat up eventually.
But it's weird to me that the room would be colder than the thermostat
setting. In the past that has never happened. It's also strange that
this problem does not occur consistently.

For what it's worth, I noticed that it appears that only one of the 2
wires from the thermostat are attached to the furnace. But it must
have been that way for the past few years, because the wire looked to
be cut and it's something I have never messed with.


Then you are NOT looking at the thermostat that is controlling the
furnace...

Maybe the anticipator in the thermostat is screwed up. So the thermostat
thinks the room is approaching the right temp and cuts off early to avoid
overshoot.

Could be....but...
The thermostat he is claiming to look at, has ONE wire hooked up...and every
single one ever, needs at LEAST 2.
A thermostat is nothing but a switch. Power in, power out. One wire, with a
cut wire hangin back...wont work, not at all.


Another possibility is the contacts in the zone valve are shot and can't
start the burner&circulator.