Why Is My Thermostat Running Aux Heat & How Do I Stop It?
Executive Summary (TL;DR) Smart thermostat features such as Nest Eco Mode force high-energy auxiliary heat (Aux Heat) to run at 100% output when restoring indoor temperatures after cold-weather absences. This bad loop is the leading cause of winter electric bills spiking beyond $600 . Restricting the Heat Pump Balance Point to 25°F–30°F or lower within your thermostat settings and securing 24V C-wire voltage stability prevents these severe utility bill spikes. 📊 Quick Visual Overview Cost Impact Metric Standard Heat Pump: ~$0.50/hr (2–4 kW draw) Aux Heat Strip: ~$3.20/hr (10–25 kW draw) ⚠️ Risk: Unchecked cycles cause $600+ monthly winter bills. Primary Failure Points Eco Delta T: Setpoint drops >5°F force emergency strip lockout override. Voltage Drop: Absence of 24V C-Wire drops O/B valve signaling mid-cycle. Balance Point: Unrestricted threshold defaults to r...