Most Upstate homes heat with a heat pump, and a heat pump runs two kinds of scenarios in winter. On the mild days that make up the greater part of a Greenville winter, it moves heat from the outdoor air at a modest cost. On the nights that drop into the 20s, which the Upstate sees more of than the rest of South Carolina, it switches on electric auxiliary heat strips that draw several times the power. Those hours are the expensive ones. Nearly everything fall maintenance does to save money comes down to keeping the second kind of situation to a minimum.
Why the strip hours cost so much
A heat pump heats efficiently by pulling warmth from outdoor air, and the colder that air, the less warmth there is to pull. Below the mid 30s, the system cannot keep up alone and calls the strips, which heat the air directly the way a toaster does, at a cost per hour well above the heat pump’s. The strips are meant for the coldest nights, and the trouble is that several common problems call them on mild nights, so a household pays strip rates for hours it never needed.
The fall items that keep the strips off
- A clean outdoor coil. The heat pump pulls warmth from the air across the same coil that shed heat all summer, and a coil hazed with pollen pulls less, so the system reaches for the strips sooner, and cleaning it in fall raises the heat pump’s capacity for the whole season.
- A correct refrigerant charge, because a heat pump low on refrigerant delivers less heat at every temperature and leans on the strips to make up the difference. The charge is measured with gauges during the tune-up and cannot be judged any other way.
- A clean filter and open vents, since restricted airflow means the house takes longer to reach the set point, and on many systems low airflow triggers the strips early. A filter every one to three months is the least expensive item on this page and the one with the fastest return.
- A tested defrost control, because a heat pump’s outdoor coil frosts on cold, damp mornings, and the defrost cycle clears it; a control that runs too often wastes heat outdoors, and one that runs too little lets the coil ice over and the strips take over, and both show on a technician’s readings.
- Strips that work only when asked, since a strip stuck on runs at every call for heat, at strip rates, without anyone noticing; a failed strip lets the house go cold on the night it is needed. Both are tested under load in the fall visit.
- A calibrated thermostat, set and left, because a thermostat reading two degrees off runs the system two degrees longer, and a thermostat moved up several degrees at once tells the heat pump to bring the strips on to get there quickly. A smart thermostat raises the temperature gradually and keeps the strips off.
The gas furnace version
Homes with a gas furnace have no strips, and the argument is simpler: every hour the burner runs costs fuel, and fall maintenance shortens those hours. Clean burners and correct gas pressure burn the fuel completely, a clean filter and open vents let the heat reach the rooms, and a tested igniter and flame sensor prevent the short cycling that wastes gas on repeated starts. The heat exchanger inspection is a safety item rather than a money one.
The habits that carry the savings through the season
The tune-up does its part in an hour, and a few habits do theirs all winter. Set the thermostat at a temperature you can live with and leave it, since a heat pump asked to climb five degrees at breakfast calls the strips to do it, and keep the overnight setback small rather than turning the system off, because reheating a cold house is exactly the job the strips are called for. Keep the outdoor unit clear of the pine straw Upstate pines drop all winter, and keep the fireplace damper closed when the fireplace is idle, since an open flue pulls heated air straight out of the house.
How to tell whether it worked
The test is January’s power bill against last January’s, allowing for rate changes and for how cold each month was. A maintained heat pump should show fewer kilowatt-hours for similar weather, and homeowners who have a neglected system tuned for the first time often see the difference within a month. If the bill does not move, the readings on the report card will say why: a duct leaking heated air into a 40-degree crawl space, a failed strip control, or attic insulation that has settled, none of which a tune-up alone can fix but all of which it can find.
Why October rather than the first cold night
The first freezing night in Greenville tends to arrive in late October or early November, and the strips that failed last winter show themselves on that night. A fall maintenance visit in October is a convenient appointment on a mild day, with time to order a part if one is needed, and the system runs at its best when the strip hours arrive in January. Members of the Carolina Comfort Club receive the fall and spring visits as part of the plan, with member pricing on repairs and priority service when the first cold snap fills the schedule.
Carolina Heating Service has served the Upstate since 1981, and the fall visit is booked online or through the 24/7 website chat, with a photo of your technician and an on-the-way message before arrival. It ends with a system report card that records every reading above and a video of the work.