HVAC School - For Techs, By Techs
Crankcase Heaters - Short #248
· Summarized
Key takeaways
- Crankcase heaters are essential for preventing flooded starts by keeping the crankcase warm when the compressor is off.
- Different types of crankcase heaters include belly bands and insertion types, each serving the same fundamental purpose.
- Proper installation, including wiring and positioning, is critical for the effective operation of crankcase heaters.
- Using an OEM crankcase heater is recommended for optimal performance and longevity of the compressor.
Summary
Introduction to Crankcase Heaters
In this section, Bryan introduces crankcase heaters, which are devices used to heat the crankcase of a compressor when it’s off. He discusses their purpose in preventing flooded starts, a condition that can cause damage to compressors by allowing liquid refrigerant to condense in the crankcase. He explains how different conditions, such as long off times and low temperatures, exacerbate the risk of flooded starts.
Types and Operation of Crankcase Heaters
Bryan outlines the various types of crankcase heaters, including belly band heaters and those that insert into the compressor sump. He explains their operational logic, specifically how they prevent refrigerant from condensing in the crankcase. The role of expansion valves and solenoid valves in conjunction with crankcase heaters is also discussed, emphasizing their importance in system efficiency.
Installation Considerations
In this section, the podcast dives into the practical aspects of installing crankcase heaters. Bryan details the necessary wiring configurations, especially the importance of connecting the crankcase heater to the line side of the contactor. He also emphasizes the need for OEM crankcase heaters and the correct positioning of these heaters to optimize their performance.
Benefits of Crankcase Heaters
The final section focuses on the benefits of using crankcase heaters. Bryan reiterates that they are valuable even in systems that don't explicitly call for them, helping to extend the life of a compressor by reducing the likelihood of flooded starts. He encourages technicians to understand these components' roles and ensure their proper maintenance.
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Show notes
In this short podcast episode, Bryan talks about crankcase heaters, including their different types, what they do, and when we need to use them.
Crankcase heaters usually come in belly band varieties, but some can be inserted into the sump of the compressor. As their name suggests, crankcase heaters heat the crankcase when the compressor is off. They prevent flooded starts since the heat keeps refrigerant from condensing to a liquid in the compressor when the system isn't running.
Long off times, long line sets, and cold temperatures all increase a system's risk of flooded starts. Hard shutoff TXVs, liquid line solenoid valves, and crankcase heaters are all ways to reduce these risks; the valves hold liquid refrigerant back, and crankcase heaters merely prevent refrigerant from condensing.
Crankcase heaters have to be wired to the line side of the contactor or starter. They're often wired around one of the contacts (with a single-pole contactor). When the contact opens, there is a circuit from one leg, through the crankcase heater and compressor windings, to the other leg. This method does NOT use the compressor winding itself as a crankcase heater. When you use a crankcase heater on a compressor with a seam, you want the part of the heater that does the tensioning near the seam. Crankcase heaters should be installed at the base of the compressor, and you'll usually use OEM crankcase heaters.
"Crankcase Heaters and Single-Pole Contactors" tech tip: https://www.hvacrschool.com/crankcase-heaters-and-single-pole-contactors/
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