Not replacing the air filter. The air filter traps dust and other particles, including pollen and microorganisms, and prevents them from recirculating in your home. The air filters in your HVAC system will eventually become clogged. If not replaced, they can block airflow and increase the HVAC system’s workload and energy consumption. A standard whole-home HVAC system needs a new air filter every three months, but may need one as often as once a month during seasons of heavy usage.

Neglecting the air ducts. The air ducts in your home may develop leaks at the seams and joints over time, which can affect your HVAC system’s efficiency. This is one of the reasons why you should have a heat pump inspection performed by an HVAC professional every year. Air ducts will require cleaning and resealing to get rid of trapped particles and bacteria within and make sure it’s airtight.

Using an outdated thermostat. While mercury or bimetal thermostats work fine, you’d be missing out on the features and savings afforded by using a programmable thermostat. If your household follows a daily routine, you can set it so that your HVAC system automatically reduces output when most of the household is out for the day. Some programmable thermostats also allow separate settings for weekends.

Ignoring leaking refrigerant. If your home utilizes a heat pump for heating, you should keep an eye out for leaking refrigerant. Unlike fuel, refrigerant doesn’t need to be recharged (the equivalent of a refill or topping off) — as long as it doesn’t leak, your HVAC system will keep providing warm or cool air. If it leaks, the HVAC system will need to compensate for the low refrigerant levels, resulting in increased strain and higher energy consumption.