Article Draft
Copper has been the standard material for HVAC and refrigeration tubing for decades, and for good reason — it combines excellent thermal conductivity, reliable corrosion resistance in typical indoor and outdoor conditions, ease of forming and joining, and a long track record of proven performance. But getting the best out of copper tubing in an HVAC or refrigeration system still comes down to choosing the right grade, sizing correctly, and avoiding a handful of installation mistakes that show up again and again in the field.
Understanding Copper Grades: DHP, DLP, and ETP
Not all copper tube is the same. DHP (Deoxidized High Phosphorus) copper is the most common grade for refrigeration and HVAC tubing, valued for its excellent weldability and resistance to hydrogen embrittlement during brazing. DLP (Deoxidized Low Phosphorus) offers slightly higher electrical and thermal conductivity, with a small tradeoff in weldability. ETP (Electrolytic Tough Pitch) copper has the highest conductivity of the three but is not recommended for high-temperature brazing or welding applications due to a risk of embrittlement, making it better suited to applications with minimal high-heat joining. For most refrigeration coil, pancake coil, and level wound coil applications, DHP is the standard choice.
Sizing Considerations
Correct tube sizing balances refrigerant velocity, pressure drop, and oil return in refrigeration systems using compressor oil. Undersized tubing increases pressure drop and can starve the system of refrigerant flow; oversized tubing can slow refrigerant velocity below the point needed to carry oil back to the compressor, leading to oil logging and eventual compressor damage. Manufacturer sizing charts and system design software account for these factors based on cooling capacity, refrigerant type, and line length — sizing shouldn’t be guessed or simply copied from a previous, different project.
Installation Best Practices
- Support tubing at proper intervals to prevent sagging, vibration fatigue, and stress at joints.
- Use the correct brazing alloy and technique for the tube grade, with nitrogen purging during brazing to prevent internal oxide scale that can later break loose and clog expansion valves or filters.
- Avoid sharp bends that reduce the internal diameter or create stress points — use proper bending tools or pre-formed fittings.
- Keep tube runs as short and direct as practical to minimize pressure drop and refrigerant charge requirements.
- Pressure test and evacuate the system properly before charging, to catch leaks and remove moisture that can cause long-term corrosion or contamination.
Common Mistakes
The most frequent issues we see traced back to tubing choices or installation are: using the wrong copper grade for high-temperature brazing, leading to embrittlement failures at joints; under-sizing tube diameter to save on material cost, leading to poor system performance and higher energy consumption; inadequate support leading to vibration-induced fatigue cracking over time; and skipping nitrogen purging during brazing, which allows internal oxide scale to form and eventually circulate through the system, clogging filters and expansion devices months or years after installation.
Maintenance & Lifespan
Properly sized, installed, and maintained copper tubing in HVAC and refrigeration applications routinely lasts the full lifespan of the system, often 20 years or more, with minimal issues beyond normal wear at mechanical joints. The overwhelming majority of premature tube failures trace back to installation error rather than the material itself, which is part of why copper remains the default choice across the industry despite decades of alternative materials entering the market.
Frequently Asked Questions
Can DHP and ETP copper tubes be used interchangeably?
Not for brazed or welded joints. ETP copper carries a higher risk of hydrogen embrittlement during high-temperature brazing due to its oxygen content, so DHP is strongly preferred anywhere brazing or welding is involved, which covers most HVAC and refrigeration installations.
How much does nitrogen purging during brazing actually matter?
Significantly. Skipping nitrogen purging allows oxide scale to form inside the tube during brazing, and that scale can break loose during operation and travel through the system, clogging filter driers and expansion valves months after installation — a failure that’s easy to prevent but expensive to diagnose after the fact.
What’s the typical lifespan of copper tubing in a well-installed HVAC system?
Twenty years or more is typical for properly sized, installed, and maintained copper tubing in HVAC and refrigeration systems, with most premature failures traced back to installation errors, like inadequate support or incorrect brazing technique, rather than the copper itself.
Does tube diameter affect refrigerant charge and system efficiency?
Yes — oversized tubing increases the refrigerant charge required to fill the system and can reduce velocity below the level needed for proper oil return, while undersized tubing increases pressure drop and reduces cooling capacity, which is why manufacturer sizing charts should guide diameter selection rather than habit or convenience.
Jaydeep Tubes manufactures DHP, DLP, and ETP copper tubes, along with finned tubes, pancake coils, and level wound coils, for HVAC and refrigeration applications. Contact our team for sizing guidance or a quote for your next project.