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Is your heat pump’s heating or cooling not in sync with the temperature setting on the thermostat?
Short cycling may be to blame.
Short cycling is when a heat pump system shuts off and restarts several times or more throughout the
day.
Below are six common causes for heat pump short cycling.
1. Thermostat Inaccuracy
Thermostats inaccurately gauging temperature can cause short cycling.
When this happens, heat pumps shut off in heating and cooling modes before set temperatures are
reached. For heat pumps with older, non-digital thermostats, the problem may be fixed by adjusting the
thermostat’s heat anticipator. The heat anticipator is located just beneath the thermostat’s cover.
Another cause for inaccurate thermostat readings is installing thermostats in the wrong place. To
gauge air temperature accurately, thermostats must be placed in areas away from sunlight and drafts
(outside air coming inside).
2. Wrong Size Heat Pump
This is the most expensive problem to fix. Short cycling may be due to a heat pump that’s too
powerful or weak for the designated heating and cooling zone.
Before installing heat pumps, a trained HVAC technician should perform a heat load calculation (also
called a manual J calculation) in the space.
The calculation determines the optimum heat pump power output for precise heating and cooling.
If inexperienced technicians fail to perform the calculation or perform it incorrectly, they may install an
oversized heat pump.
3. Clogged Air Filter
Heat pump air filters keep airborne contaminants from being sucked into the sensitive working parts of
the system. But when air filters aren’t cleaned at prescribed service intervals, they eventually clog, causing
restricted airflow, which results in overheating.
When heat pumps overheat, they shut down. Short cycling from overheating can cause serious damage.
To avoid this, check the air filter at the prescribed service intervals and clean or replace it as needed.
In the extremely cold and hot seasons when heat pump usage levels are higher, checking air filters
monthly is advisable.
4. Leaking Refrigerant
A heat pump’s air conditioning, or air-cooling function, is done through a process that relies on
refrigerant. During cold weather, the refrigerant transfers heat from the outdoors before pressurizing it
and releasing it into the inside space.
But when a heat pump is leaking refrigerant, the heat pump will short-cycle and fail to adequately heat
the space. Ice buildup on the outdoor heat pump unit is a common sign of a refrigerant leak.
When ice buildup is evident, a trained technician should be contacted ASAP.
5. Dirty Evaporator and Condenser Coils
Evaporator coils and condenser coils are heat pump system components that absorb heat and moisture
from the air and remove heat from the refrigerant to cool and heat buildings and homes.
These copper, steel, and aluminum coils should perform optimally as long as they are kept clean.
Dust and grime build up interfere with the heat exchange process, causing heat pumps to
shut down and start up irregularly.
Located in outdoor heat pump units, condenser coils can be cleaned by hand using a soft brush and
water from a spray bottle or a gentle garden hose.
Evaporator coils may be less accessible to homeowners and other non-technicians as they are located in
indoor air handling units. They can be cleaned with a soft brush and or microfiber towel.
6. Aging Heat Pump
Heat pumps 15 years old and older tend to malfunction, with short cycling being a common issue. Old
machines should be monitored and replaced before they cause discomfort and inconvenience.
Chillwell. Trusted Heat Pump Repair and Installation.
Is your heat pump broken or not running well? You need the best team working on the problem. Give
your friendly, trained Chillwell technicians a call today!
