Chronological Sequence of Events
1.Programmable Thermostat installed in 2007, and was working as programmed
2.New Brock Furnace installed in April of 2009.
3.Furnace has run randomly as if it has a mind of its own, since the installation
4.Sometimes the air is heated and sometimes not
5.Service specialist says this is normal, has made some adjustments, but nothing has been resolved.
5.Would the problem be corrected if a simple Heat/Cold manual thermostat was installed?

Usually it is the thermostat or a intermitent short in the thermostat wiring that is the problem. Now if it is just the air move/blower fan that is causing the problem an adjustment to the fan and limit control or fan control itself could be the problem. It could also be the adjustment for heat anticipation in the thermostat if so equipped.

The thermostat may have setup options that worked well with the previous furnace, but require adjustment for the new one.

Usually it is the thermostat or a intermitent short in the thermostat wiring that is the problem. Now if it is just the air move/blower fan that is causing the problem an adjustment to the fan and limit control or fan control itself could be the problem. It could also be the adjustment for heat anticipation in the thermostat if so equiped.

Thank you for the assistance.
Rkw

The thermostat may have setup options that worked well with the previous furnace, but require adjustment for the new one.

Thank you for the assistance.
Rkw