'If it cools in July it'll heat in December': the Jacksonville heat pump myth

The belief we hear every autumn

Say it the way we hear it in Mandarin and Baymeadows every autumn: “The system ran fine all summer, so it’s fine.”

It is a reasonable belief. A heat pump is one machine. If the compressor, the fan and the coil carried a house through a Jacksonville August with its 90-degree afternoons and 73-degree dew points, surely a few 40-degree mornings are easy.

The trouble is that heating mode uses parts that cooling mode never touches. The reversing valve has to shift. The defrost board has to sense frost on the outdoor coil and clear it. The electric heat strips have to come on as backup and, more importantly, go off again. The thermostat has to stage all of that correctly. None of those components has done a thing since March, and a city that averages about 14 freeze nights a winter, with the first typically in early December, is going to ask every one of them to work on short notice.

That is why a Jacksonville heat pump needs a fall visit that runs the system in heat, even when it is 78 degrees outside and nobody can imagine wanting it.

What a fall heat pump visit is not

• It is not a filter change with a signature. You can change the filter yourself and should.
• It is not a visual check from the driveway. If nobody opens the condenser panel and the air handler, nothing was maintained.
• It is not a sales visit. If the system is healthy, the visit ends with a record and a date for the next one, and nothing is pitched.
• It is not a cooling-only check in autumn. The fall visit runs heating mode, period.
• It is not a once-a-year event here. With cooling from late May to late September and heating in a cluster of winter mornings, the two seasons wear different parts and want their own visit.

What it is: both modes, every reading written down

A measured inspection of the whole system, in both modes, with every reading written down, plus the cleaning and small corrections that keep a heat pump from becoming a repair. In Jacksonville that includes specific attention to the four things this climate attacks: pollen on the outdoor coil from February through May, algae in a drain line that runs most of the year, salt on anything within a few miles of the ocean at Mayport, the Beaches or Amelia Island, and surge damage from the summer storms that give Northeast Florida some of the highest lightning counts in the country.

Ten steps, both modes

1. Conversation. How the system behaved last season, whether the JEA bill moved, what rooms run hot or cold.
2. Thermostat. Reading verified against a calibrated thermometer, staging checked so the strips are backup, schedule reviewed.
3. Filter and return. Filter replaced or noted; return size checked against the equipment, which matters in pre-1950 Riverside, Springfield and Ortega homes with ducts added later.
4. Air handler. Blower wheel and motor, evaporator coil condition, capacitor value, wiring, strip heat elements and sequencers, drain pan, drain line flushed and treated, float switch tested.
5. Outdoor unit. Coil rinsed, fins inspected for salt damage, fan motor and capacitor tested, contactor inspected for pitting, wiring and disconnect checked, surge protection noted or recommended.
6. Refrigerant. Pressures and temperatures recorded, superheat and subcooling calculated, charge corrected only if a leak search is done first.
7. Heating mode. Reversing valve shifted and confirmed, defrost board and sensor tested, strip heat engaged and disengaged, temperature rise measured.
8. Cooling mode. Temperature split across the coil, amp draw on the compressor at steady state.
9. Ducts. Static pressure measured; obvious leaks, crushed flex or disconnected runs noted, especially in the attics of 1950s to 1970s Arlington and Westside ranches.
10. The report. Readings, findings, and a recommendation only if the numbers warrant one.

Schedule a heat pump tune-up

Preparing the house

A few minutes before we arrive saves time on the clock:

• Clear a path to the air handler, whether it is a hall closet in a San Marco bungalow, a garage in Sunbeam or an attic hatch in Avondale.
• Trim back shrubs and move anything stored against the outdoor unit. Two feet of clearance is the minimum.
• Know roughly how old the system is and who installed it, if you can.
• Write down the complaint, if there is one: the room that never cools, the noise at startup, the bill that jumped.
• Keep pets in a closed room. Technicians open doors and panels, and a Jacksonville garage is a tempting exit.
• If the house is a rental, make sure the tenant knows we are coming and that the thermostat will be moved around.

Timing and the agreement

The spring visit belongs in March, April or early May, after the worst of the oak pollen and before the first 90-degree week. The fall visit belongs in October or November, before the first freeze. Cook’s service agreements put both on the calendar with priority scheduling and member pricing on any repairs found along the way; ask for the exact inclusions. [[CONFIRM WITH JERRY]] JEA runs its own HVAC tune-up program, and whether a Cook’s visit qualifies under it is also [[CONFIRM WITH JERRY]].

The maintenance route for Jacksonville runs up I-95 from the Palm Coast headquarters, and the fall list fills early. The homeowners who book in September are the ones not calling at 6 a.m. on the first 28-degree morning.