Originally Posted by
RyanHughes
20 kW strip heat with a 3 ton heat pump? Don't think you need that. Not in OR.
Keep us posted on what the dealer finds. I have a similar system (4 ton), and aux heat is only needed at cold outdoor temps (i.e., <35 deg), and even then only periodically as it maintains temp (I believe the factory setting is 5 cycles per hour [CPH] for auxiliary heat). The communicating thermostat cycles the heat strips in stages based on demand, and there is a CPH setting that can be adjusted. How large is your home (sqft)?
Like duckman said, I also did not want the 950 thermostat due to issues with the TAM8. The 900 thermostat is a fine, fully functional communicating thermostat. Understand that what you're seeing may be normal. The 3 ton ZM 20 is rated at ~34,000 btuh @ 47 deg F and ~27,400 btuh @ 37 deg F. Depending on your size home, setback conditions, outdoor air infiltration, etc., it could very well be normal for the thermostat to briefly cycle heat strips in an attempt to maintain setpoint, although with a 3000 sqft home and 4 ton HP in Maryland, I don't see auxiliary heat at 40+ deg F outdoor temp. Was a load calculation done on your home prior to sizing the new equipment? What is the total heat loss of your home (btuh) at design conditions?
Your system is under warranty. The refrigerant charge could be confirmed. Do you know if your installer charged the system using the automated ChargeAssist feature?