Crankcase Heater
A crankcase heater is an electric heater mounted on or near an HVAC compressor to keep the crankcase warm when the system is off. It prevents refrigerant from migrating into the compressor oil and diluting it, which can cause damage on startup.
💡 Key Takeaways
- ✓A crankcase heater is an electric heater mounted on or near an HVAC compressor to keep the crankcase warm when the system is off. It prevents refrigerant from migrating into the compressor oil and diluting it, which can cause damage on startup.
- ✓More common in commercial systems but useful in cold‑weather residential installs.
- ✓Typically controlled by a thermostat or control circuit to limit energy use.
- ✓Should be sized and installed by qualified HVAC technicians.
Crankcase Heater
/ˈkræŋkˌkeɪs ˈhiːtər/
Definition
A crankcase heater is an electric heater mounted on or near an HVAC compressor to keep the crankcase warm when the system is off. It prevents refrigerant from migrating into the compressor oil and diluting it, which can cause damage on startup.
Why is a crankcase heater important?
It keeps refrigerant out of compressor oil during off cycles, preventing startup damage.
Source: The Cooling Company
Quick Facts
How Crankcase Heater Works
Crankcase heaters protect compressors during off cycles.
Real-World Application
In cooler climates, a crankcase heater keeps the compressor warm during winter so spring start‑ups don’t cause oil dilution or damage.
Pro Tip
Have the heater checked before cold weather to confirm it is energized and working properly.
“Have the heater checked before cold weather to confirm it is energized and working properly.”
Important Things to Keep in Mind
- More common in commercial systems but useful in cold‑weather residential installs.
- Typically controlled by a thermostat or control circuit to limit energy use.
- Should be sized and installed by qualified HVAC technicians.
Did You Know?
Crankcase heaters significantly reduce seasonal compressor failures caused by refrigerant migration.
FAQ
Does every HVAC system need a crankcase heater?
Not always. They’re most important in colder climates or systems with long off cycles.
How do I know if my crankcase heater failed?
A technician can test heater continuity and amperage during maintenance.
Does a crankcase heater use a lot of energy?
It uses a small amount of power and typically runs only when needed.
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