Our Rheem heat pump (installed when the house was built in 1994)services our basement level (has our kids bedrooms and family room). It has been extremely cold lately but only last night it started to run constantly on aux/emergency (red light) heat and will not pay attention to the thermostat setting (66F) - it is heating to almost 80F down there! We have changed the thermostat to the energy savings setting which is supposed to not use the emergency heat but nothing is working. At this rate, our electric bill next month will be out of this world! Any advice on troubleshooting this would be great! The Totaline brand t-stat is a programmable and digital one (2 yrs old) - uses 2 AA batts and gives a low batt message when applicable (which it is not doing now). I can't find any posts about anything like this - usually the heat pumps won't heat well enough in cold weather (which we have also experienced in the past). Thanks in advance!

If you turn the thermostat off does the aux/em heat shut down?

If you turn the thermostat off does the aux/em heat shut down?

It does but if you turn it back on, after 15 minutes or so, it comes right back and escalates the temperature way above the setting again. At this point, we've turned the unit off at the thermostat and hope the basement is insulated enough to maintain a decent temp through the night and tomorrow until temps rise again.

Sound like it could be

A bad thermostat

Tomorrow is another day.