Heat pump and no-heat calls in Jacksonville

The First Coast is the part of Florida where the heating side of a heat pump earns its keep. Jacksonville's January normal low is 42.9 °F, December 45.8, February 46.1, and the cold fronts that follow a winter rain drop the nights lower than that. Most houses here heat with the same system that cools them: a heat pump with electric heat strips as backup, or, in older houses, an air handler with strips and no heat pump at all.

On a cold night the not-cooling page's checks apply in reverse: thermostat set to Heat, breakers on, and a look at what the outdoor unit is doing before you decide it has failed.

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What is normal on a cold, damp night

A heat pump does three things that look like a failure and are not; a fourth, Emergency Heat, is a setting people leave on by mistake.

• Defrost: in cold, humid air the outdoor coil ices; the unit stops the outdoor fan, runs in reverse for a few minutes, and steam rises off the coil. Indoors the air goes cool until the strips take over. Five to ten minutes, then back to heating.
• Cool-feeling air: a heat pump delivers air at 85 to 95 °F, warmer than the room but cooler than your skin. It is heating; it does not feel like a furnace.
• Auxiliary heat on the thermostat: the strips are running alongside the heat pump on the coldest nights. Normal. "Emergency Heat" selected by hand is not: it runs the strips alone at three times the cost, and a thermostat left there since a cold snap is a common reason for a high electric bill in February.

What is a call

The list a contractor wants to hear on the phone.

• Air that stays cool for an hour with the thermostat set to Heat, or a house that never reaches the setpoint on a night above freezing.
• A breaker that trips when the strips come on: strips draw a lot, and a weak breaker, a burned wire, or a failed sequencer shows itself in January.
• Ice that does not clear: a block of ice on the outdoor unit that stays through the day is a defrost board, a sensor, or a low charge.
• The outdoor unit not running at all with the indoor fan blowing: a contactor, a capacitor, or a reversing valve stuck in cooling.
• A burning smell the first time the strips run is dust and lasts minutes; a smell that continues, or any smell from the panel, is a call and the breaker goes off.

Replacing a heat pump or adding one

A heat pump replacement follows the same rules as a cooling replacement (14.3 SEER2 and 7.5 HSPF2 minimum, R-454B or R-32 in new equipment, a mechanical permit) with one local addition: the strips. Ask that the strip kit be sized for the house rather than copied from the old air handler, because it decides the breaker and the wire. JEA's rebate wants 16 SEER2 and 8.0 HSPF2 on a heat pump; Clay Electric's Energy Smart credit is specifically for heat pumps at 15.2 SEER2 or higher.

An older house with strips and no heat pump (common in the 1950s and 1960s block houses in Arlington, Lakewood and the Beaches) can get a heat pump at replacement time; the same outdoor unit then cools in July and heats in January, and the strips become backup.