How each one makes heat
A heat pump does not create heat. It runs the air conditioning cycle backwards, moving heat that already exists in the outdoor air into your house. Because it is moving heat rather than generating it, it delivers substantially more heat energy than the electrical energy it consumes.
Heat strips are electric resistance elements — the same principle as a toaster. Every unit of electricity becomes exactly one unit of heat. Reliable, simple, and far more expensive to run.
Why heat pump air feels cool
A gas furnace delivers air around 120–140°F. A heat pump typically delivers air in the 85–95°F range. That is warmer than your body temperature's comfort threshold at the vent, so it can feel cool on your hand even while it heats the house correctly.
This is normal and not a fault. The house will reach setpoint; it does so gradually rather than in blasts.
When AUX or EM heat is supposed to run
AUX heat is designed to engage in two situations: when it is cold enough outside that the heat pump alone cannot keep up, and during the defrost cycle, when the outdoor coil is briefly being cleared of frost and the system would otherwise blow cold air indoors.
EM (emergency) heat is different. It locks out the heat pump entirely and heats on strips alone. It exists for when the heat pump has failed. It is not a 'heat the house faster' button, and leaving it on for a season is genuinely expensive.
When AUX heat means something is wrong
Call if you see any of these:
- AUX indicator on when it is 55°F or warmer outside.
- AUX running constantly rather than briefly during defrost.
- The outdoor unit iced over and staying that way instead of clearing.
- A winter power bill that doubled with no change in how you run the thermostat.
The thermostat detail that costs real money
Large setbacks work against a heat pump. If you drop the house eight degrees overnight and then ask for it back quickly in the morning, the thermostat sees a large gap and brings the strips on to close it — spending resistance-heat money to recover.
Smaller setbacks of two to three degrees, or a thermostat with true adaptive recovery that is configured for a heat pump, keep the system on the efficient side of that handoff. A thermostat configured for a furnace instead of a heat pump will quietly run strips all season.
Want it measured instead of guessed?
The readings that settle this — pressures, superheat and subcooling, amp draw, static pressure — take a visit. You get the price in writing before anything is replaced.
(904) 467-1100