HVAC maintenance: schedule, lifespan and costs
Updated
Overview
The central heating and cooling system is the furnace or air handler inside, the air conditioner or heat pump outside, and the ducts that carry air between them and the rooms. It runs more hours than anything else in the house, and it's the most expensive thing in it to replace. Most of what keeps it going is small: a filter changed on time, a drain line kept clear, an outdoor unit kept clean, and a technician's visit before each season to catch what's drifting out of adjustment. The jobs below are the whole list.
Lifespan
A central HVAC system lasts 15 to 20 years. The air conditioner and the furnace age at different rates, and in a system that's been well kept the furnace often outlasts the air conditioner, since the outdoor unit lives in the weather.
What shortens that life is strain. A clogged filter starves the system of air, and the blower and the compressor work harder for every hour of it. A dirty outdoor coil can't shed heat, so the compressor runs hot. Skipped tune-ups let small faults, a low refrigerant charge or a loose connection, grind on until they take a major part with them. What extends it is the opposite: clean filters, clean coils, and a technician's visit once or twice a year.
The signs a system is near the end: repairs that come every season, a compressor or heat exchanger that fails, energy bills climbing while the house gets less comfortable, and refrigerant of a type that's no longer made. A system past the middle of its lifespan with one of those is a system to start planning around.
Maintenance schedule
The jobs that keep a central system running, in the order they come up through the year.
| Task | How often |
|---|---|
| Replace the HVAC filter | every 1 to 3 months |
| Clean the AC condensate drain line | every 1 to 3 months during cooling season |
| Get an HVAC tune-up | once or twice a year |
| Clean and check the outdoor AC unit | once a year, before cooling season |
| Clean the air vents and registers | every 6 to 12 months |
| Replace the furnace humidifier pad | once a year, at the start of heating season |
| Winterize the air conditioner | once a year, after the last use in fall |
Replacement cost
Replacing a central system costs $5,000 to $12,000 installed, for a matched furnace and air conditioner or a heat pump system. The range depends on the size of the house, the efficiency rating you choose, and whether the ductwork needs work at the same time. Replacing only the air conditioner or only the furnace costs less, but mismatched halves run less efficiently and often fail sooner, which is why contractors push to replace both together.
The repair-or-replace rule: if the repair would cost more than half of a new system and the equipment is past the middle of its lifespan, replace it. A compressor or a heat exchanger on an old system is a replacement. A capacitor, a blower motor, an igniter or a refrigerant leak on a younger system is a repair.
Common problems
- Weak airflow at the vents: a clogged filter, nearly every time. Replace the HVAC filter and see if it clears.
- The AC runs but the air isn't cold: a dirty outdoor coil, a frozen indoor coil from poor airflow, or a low refrigerant charge. Clean and check the outdoor AC unit, and call for a tune-up if that doesn't fix it.
- Water around the indoor unit, or the AC shutting itself off in summer: a clogged condensate line tripping the float switch. Clean the AC condensate drain line.
- The furnace starts and stops in short bursts: overheating from a clogged filter, a dirty flame sensor, or a failing limit switch. Change the filter first, then get an HVAC tune-up.
- Rooms that heat or cool unevenly: blocked registers, closed dampers, or leaky ducts. Clean the air vents and registers, and ask the technician to check the ducts.
- Dry air and static in winter: the humidifier pad is crusted over. Replace the furnace humidifier pad.
FAQ
How long does a central HVAC system last?
About 15 to 20 years. The outdoor unit usually goes first, since it lives in the weather, and a system that's kept clean and tuned reaches the long end of the range.
How much does it cost to replace an HVAC system?
$5,000 to $12,000 installed for a matched furnace and air conditioner or a heat pump system, depending on size, efficiency and the state of the ducts.
Should I replace the furnace and air conditioner at the same time?
Usually. Matched equipment runs more efficiently, and a new half paired with an old one often fails early. If one side is young and the other is old, replace the old side alone.
What maintenance does an HVAC system need every year?
A filter change every 1 to 3 months, a clear drain line through cooling season, a tune-up once or twice a year, a clean outdoor unit before summer, and a cover on it after the last use in fall.
Is a yearly HVAC tune-up worth it?
Yes. It costs $75 to $200 per visit, catches faults while they're small, keeps the warranty valid, and is the main thing that gets a system to the end of its 15 to 20 year life.