The furnace gets switched on the same week as the Nights of Lights

The calendar sets the deadline

The Nights of Lights switch on in the Plaza in mid-November, and for a lot of St. Augustine households that’s the signal that the season has changed. Within a few weeks the first real front pushes through, overnight lows drop toward the upper 40s, and furnaces that have sat idle since February get asked to light.

A furnace that hasn’t run in nine months is a furnace nobody has checked in nine months. The flame sensor has oxidized in the humidity. The burner compartment has collected dust, dead insects and the occasional lizard. The condensate trap on a high-efficiency model has the same algae growing in it that clogs every AC drain in the county. An electric furnace has strips that may have burned open in the summer surge season without anyone knowing, because nothing called for heat. The heating check we do in November is how all of that gets found before the front arrives, instead of on the first 38-degree morning when every heating contractor in St. Johns County is already booked.

A short heating season is hard on a furnace

It sounds backwards, but St. Augustine’s mild winters age furnaces in their own way. Equipment that runs steadily all winter in a cold climate stays dry and exercised. Equipment that sits for most of the year in a 120-degree attic or a damp crawlspace, then runs hard for a few weeks, goes through more thermal cycles per hour of use and more corrosion per year of life. The average lows here, 47 to 51 degrees in the coldest months, mean a furnace short-cycles constantly: it reaches setpoint fast, shuts off, and starts again twenty minutes later. Ignitors, sequencers and contactors count cycles, not hours.

Add the salt that reaches every house east of US 1, the king-tide flooding that puts water in Davis Shores garages where furnaces live, and the summer lightning that takes out control boards nobody tests until November. A furnace here needs its annual visit more than one in a colder place, not less.

What that means for each kind of heat

Electric furnaces and heat strips. The most common heating in St. Augustine, found in nearly every block ranch in the Shores and the South and in every 2000s subdivision house as the backup inside a heat pump air handler. The strips are simple and the failures are quiet: one element of four burns open, the house still heats, and the FPL bill carries the difference until someone tests them.

Gas furnaces on Peoples Gas. Fewer, but they carry safety stakes the electric ones don’t. A heat exchanger crack or a vent problem produces carbon monoxide, and a furnace that only runs a few weeks a year can hide one for a long time. The combustion analysis and CO test are the core of a gas furnace visit.

Dual-fuel systems. A heat pump paired with a gas furnace, switching between them by outdoor temperature. These need both halves checked and the changeover setting verified; a wrong setpoint runs expensive gas heat on mornings the heat pump could have handled.

Mini-split heat pumps in the historic districts. Not furnaces, but they’re the heating in Lincolnville and the Colonial Quarter, and the November visit covers them: defrost, reversing valve, outdoor coil and the drain.

Twelve points we hit on every furnace

1. Filter replaced and the homeowner’s schedule reviewed.
2. Blower wheel inspected, cleaned if loaded, motor amperage recorded.
3. Static pressure measured across the air handler to catch duct problems that trip limits.
4. Electric: every heat strip tested under load, with amp draw per element and sequencer timing recorded.
5. Gas: burners cleaned, ignitor and flame sensor cleaned or replaced, gas pressure checked.
6. Gas: heat exchanger inspected, vent and draft checked, combustion analysis and carbon monoxide reading taken.
7. Limit switches and safeties tested.
8. Control board, relays and wiring inspected for surge damage and tightened.
9. Condensate drain and pan under the coil cleared and treated; furnace condensate trap cleaned on high-efficiency gas models.
10. Cooling coil inspected and cleaned if the wet season left a coat on it.
11. Thermostat heating configuration verified, including auxiliary lockout on heat pumps and changeover on dual-fuel.
12. A full heating cycle run and the temperature rise measured against the manufacturer’s range.

Findings are written down and left with you, with a price for anything that needs a decision.

Schedule a furnace tune-up

Between now and next December

The furnace will sit again from March until the next Nights of Lights. A few things keep the next November visit short:

• Keep the filter schedule through the cooling season; a filter that chokes the AC in July chokes the furnace in December too.
• Don’t store anything against the furnace cabinet or in front of the burner compartment. Garage furnaces in the Shores tend to disappear behind beach gear by August.
• After any flood tide that reaches the garage floor in Davis Shores or along the bayfront, leave the furnace off until it’s been inspected.
• If a carbon monoxide alarm sounds at any time of year, treat it as real, get out, and call.
• Run the heat for a few minutes once in October, before you need it. A furnace that won’t light in October is a scheduled repair; one that won’t light in December is an emergency.

Cook’s maintenance agreements pair this November visit with the spring cooling tune-up, with priority scheduling and member pricing; the office confirms the current inclusions. [[CONFIRM WITH JERRY]] We maintain every major brand of furnace and install Lennox when a furnace has reached the end of its safe life.