Mid efficiency furnace started acting up a couple years ago. Use a
Honeywell Magicstat thermostat to control. When the setpoint on the
thermostat changes by more than 1 degree, the furnace comes "on" and
heats up and acts as one would expect. Once the thermostat measures an
increase of 1 degree C, the furnace burners shut off and the blower
stays "on". Note that the temperature has not reached the setpoint. It
has only gone up 1 degree. The furnace blower stays on and circulates
the air, and the burners never come back "on" again. In fact, the
temperature will start to drop in the house and the burners never come
back on. But the blower stays on. The only way to get the temperature
up to its setpoint is to manually increase the thermostat 1 degree at
a time, wait for the temp. to go 1 degree, then increase it 1 more
The thermostat was suspected to be the problem and has been replaced.
The problem is still there with the new thermostat.
Suggestions anyone? Has anyone heard of this happening before?