A calendar built for the Tennessee Valley
Huntsville sits low in the Tennessee Valley, and its weather swings between muggy summers and short, sharp winter freezes. NOAA's engineering weather data for the Huntsville/Madison station is the reference point for sizing equipment here, and it makes a good guide for upkeep as well. The tasks below are grouped by when they pay off most, so the system is ready before each season arrives.
March: get ahead of the heat
- Replace or wash the filter, then set a monthly reminder through October. Spring pollen in north Alabama turns filters yellow fast.
- Hose the outdoor coil from the inside out with low pressure after shutting off power at the disconnect. Mowing season packs grass clippings into the fins.
- Trim shrubs back so the unit has open air on all sides.
- Schedule the spring service visit early. Ask for refrigerant pressures and temperature split to be written on the ticket.
May to September: fight the moisture
NOAA counts about 935 hours in an average year at the Huntsville/Madison station when the wet-bulb temperature is above 73°F. That is a long humid season, and much of the system's work is pulling water from the air.
- Keep an eye on the condensate drain. A clogged line can flood a hallway closet or an attic ceiling. Pour a cup of white vinegar into the access port each month if your technician recommends it.
- Use a hygrometer. Indoor relative humidity that stays high on a hot afternoon points to airflow, sizing or duct leakage problems worth raising with a pro.
- Seal and insulate attic ducts if they sweat. Condensation dripping onto drywall is a common Huntsville callback.
October: switch over carefully
- Run the heat on a cool afternoon before you need it, so a failed igniter or a stuck reversing valve shows up while help is easy to book.
- Replace thermostat batteries and confirm the schedule still matches your household.
- Check that outdoor vent caps are clear of wasp nests and leaves.
December to February: short, hard freezes
The Huntsville/Madison station averages 40 freeze-thaw cycles a year, and the 50-year frost depth is 9 inches. Cold spells are brief but real.
- Know your backup heat. Ask your technician at what outdoor temperature a heat pump's auxiliary strips take over, and how to tell when they are running.
- Protect the outdoor unit from roof runoff. Water dripping onto a heat pump during a freeze can encase the coil.
- Prepare for snow. The February 25, 2015 storm dropped 5 to 12 inches across most of north Alabama. Keep the outdoor unit and any high-efficiency furnace intake and exhaust pipes clear of drifts.
Replacement and permits
The City of Huntsville says plumbing, electrical, gas and mechanical work must be permitted by the contractor holding the appropriate license for that trade. On a replacement, that means the HVAC contractor pulls the mechanical permit, and a gas line or new circuit may involve another trade's permit. Ask who is pulling each one before you sign, and keep the permit number with your records.
Keep notes between visits
A short log of filter changes, service dates and repair notes helps the next technician and shows you when the equipment has started costing more than it saves.