03/04/2026
Top 10 tips for heat pumps
1 Choosing the operating mode
Most modern air-source heat pumps provide heating
and cooling, but it is best to manually select heat
mode during the heating season and switch to cool
mode when you want air conditioning, instead of
using Auto mode.
• Dry mode reduces extra humidity on days that
aren’t hot enough to need full cooling.
• Auto mode automatically switches between
heating and cooling based on the indoor
temperature. In mild climates, this can cause
the system to switch back and forth too often,
lowering comfort and increasing energy use.
2 Understanding your heat pump’s
defrost cycle
Some newer heat pumps’ defrost function is barely
noticeable; others, however, can be confusing.
When outdoor temperatures drop below about 40 F,
frost can form on a heat pump’s outdoor unit. This
is normal, and the system will automatically enter
defrost mode, briefly pausing indoor heating to melt
the ice. After a few minutes, normal heating resumes.
During this time, you might notice:
• The indoor fan stops
• Indicator lights on the unit blink or turn on
• Water dripping or steam rising from the outdoor unit
• Whirring, clicking, or fluid-moving sounds from
the indoor and outdoor units
• The compressor sounds louder than usual
Defrost cycles usually last 5–15 minutes. Let the
system run on its own and do not interfere. Trying
to stop or adjust it can delay your heat from turning
back on.
3 Fan speed: Let the system decide
Using the auto fan setting is best. Your heat
pump will choose the right speed for comfort and
efficiency.
You can adjust manually for:
• Medium or High to heat a room faster or spread
heat more evenly
• Quiet for naptime, movies, or nighttime use
4 Setting the temperature
Most modern heat pumps work differently from
older wall thermostats. Instead of showing the
exact room temperature, they use your “comfort
number.” Find and set your comfort number, and
the system will keep your home comfortably heated
or cooled.
5 Don’t keep changing the temperature—
set it and forget it!
Modern heat pumps work best when left
alone. Once you and your contractor find your
ideal comfort setting, leave it. If you need to
make a change, adjusting no more than 3F is
recommended. Patience is key, as you will need to
give your system time to respond to the new setting.
6 Get to know your backup heat
Some heat pumps have a secondary or backup
heat source for very cold days. Ask your contractor
if your system has one and understand what role
you may-or may not-need to play, so you know what
to expect.
Top 10 tips for heat pumps continued
7 Operating your heat pump in very cold
or severe weather
In very cold, snowy, or icy weather, you may need
to take a few extra steps:
• Clear snow away from the outdoor unit
• Temporarily raise the temperature setting
• Close doors to unused rooms (for ductless
systems)
• Use backup heat if your system has it
8 Keep your filters clean
Clean filters help your heat pump work efficiently,
whereas dirty filters reduce airflow and lower
heating and cooling performance. How often you
clean or replace them depends on your home. For
example, households with pets or indoor smoking
may need to replace filters more often. Ask your
contractor how often you should clean and/or
replace your filter.
9 New or unfamiliar sounds are normal
Your heat pump might make sounds you haven’t
heard before, such as:
• Low fan noise
• Clicking or fluid-moving sounds
• Changes in the compressor sound
Call your contractor if:
• Lights flash error codes
• Sounds become louder or unusual
• Persistent odors appear after the system hasn’t
been used
10 Read the owner’s manual
The manual contains all the details about how
your heat pump works, its features, and how to
care for it. Reading and familiarizing yourself with
it can help keep your system running efficiently
and reliably for years
