Why Filter Driers Matter in HVAC Systems
A filter drier is a small but critical component that protects air conditioners and heat pumps from premature failure. Its main job is to remove moisture, acid, and debris from the refrigerant, keeping the compressor and metering device safe. Without a proper filter drier, contaminants can cause blockages, corrosion, or even total system breakdowns.
When You Must Use a Filter Drier
1. On Every New Installation
Most manufacturers require a liquid-line filter drier to be installed during new AC or heat pump installations. This not only ensures a clean system but also protects your warranty coverage.
2. After a Compressor Burnout
If a compressor fails, it often leaves behind acid, carbon, and metallic debris. In this case, both a liquid-line and a temporary suction-line filter drier are strongly recommended to catch contaminants before they damage the replacement compressor.
3. After Major Repairs
Whenever the refrigerant circuit is opened — for example, replacing a coil, metering device, or compressor — a new filter drier should be installed. This prevents moisture and debris from circulating through the system.
4. When Contamination Is Suspected
If there are signs of acid, moisture, or dirt in the system, replacing the filter drier can help clean the refrigerant and avoid future callbacks.
Types of Filter Driers and Placement
- Liquid-Line Filter Drier: Installed before the expansion device; this is the most common type and required on almost every installation.
- Suction-Line Filter Drier: Installed before the compressor; used mainly after a burnout or severe contamination event and often temporary.
When It May Not Be Needed
- If the system is factory-sealed and hasn’t been opened, the factory-installed drier is generally enough.
- If you’re doing non-refrigerant service (like electrical or airflow issues), a new filter drier isn’t required.
Best Practice for Technicians
✅ Rule of Thumb: Anytime you open the refrigerant circuit or replace a compressor, you should also install a new filter drier.
This not only protects the system but also ensures compliance with manufacturer specifications and building codes.
Conclusion
A filter drier is a small investment that can prevent major system failures and costly callbacks. For wholesalers, stocking reliable liquid-line and suction-line filter driers ensures your contractor customers are always equipped to follow best practices.
