When it comes to cleaning shell and tube heat exchangers, there’s a right way—and then there’s the fast, ineffective way that leads to callbacks, poor system performance, and unhappy customers. 

For HVAC contractors, especially those working in commercial environments, mastering proper tube cleaning is essential. Whether the exchanger is fouled with mud, biological debris, or a bit of calcium scale, this guide covers best practices for thorough, professional cleaning that restores system performance and leaves a lasting impression. 

Step 1: Prioritize Safety

Before beginning any tube cleaning, the unit must be fully isolated. Power should be shut off, valves closed and tagged, and the system allowed to cool. All fluid should be drained from the exchanger. 

Appropriate personal protective equipment (PPE) should be worn—especially when dealing with biological material—to ensure safety and prevent exposure to harmful contaminants. 

Step 2: Inspect Before Cleaning 

A borescope inspection should be conducted before cleaning begins. Checking a sample of tubes provides valuable insight into the type and severity of fouling and establishes a baseline for documentation. 

Capturing images or video during inspection can serve internal reporting purposes and reinforces credibility with the customer, especially when showing before-and-after conditions. 

Step 3: Mechanical Tube Cleaning with Integrated Water Flush

For soft fouling such as mud, sludge, or biofilm, a tube cleaning system with integrated water flush is the most effective solution. 

Use nylon or similarly soft brushes to scrub the inside of the tubes while simultaneously flushing with water. This dislodges and removes debris without compacting it further into the exchanger. Several systems on the market, including rotary shaft cleaners with water injection, are specifically designed for this application.

Cleaning should continue until water exiting the tubes runs clear, indicating a successful removal of contaminants. 

Step 4: Addressing Limescale and Hard Deposits

If limescale or calcium deposits are discovered during the initial inspection, the following options are recommended: 

• Use brass or steel brushes for mechanical removal of mineral buildup.
• For more significant scale, conduct an acid flush using a non-corrosive, inhibited descaler appropriate for the heat exchanger’s materials of construction. 

Acid cleaning should only be used when necessary and always followed by proper neutralization and flushing. 

Step 5: Final Flush and Post-Cleaning Inspection

After mechanical cleaning is complete, flush the entire system with water until all debris is fully cleared. No additional cleaning agents are required—clean water is sufficient when used thoroughly. 

A second borescope inspection is recommended to confirm successful cleaning. Visual confirmation of restored tube condition ensures quality control and supports customer satisfaction. 

Step 6: Reassembly and Site Cleanup

Reassemble the exchanger using manufacturer-recommended torque specifications and gaskets. Pressure test the system if required before placing it back into service. 

Clean the exterior of the exchanger and the surrounding area. All tools, hoses, and materials should be cleared and stored, leaving the space cleaner than it was found. A clean work area reinforces professionalism and attention to detail. 

Step 7: Customer Communication and Recommendations

Once cleaning is complete, review findings with the customer. Show pre- and post-cleaning images when available and explain any observed conditions. 

Offer preventive recommendations as needed: 

• Install or maintain upstream filtration or strainers
• Evaluate water treatment options for biological or particulate issues
• Suggest an appropriate cleaning schedule based on system use and water quality 

The Standard for Professional Tube Cleaning Cleaning shell and tube heat exchangers is a high-value maintenance service that, when done properly, restores efficiency, prevents costly downtime, and strengthens customer trust. For HVAC contractors, taking the time to inspect, clean thoroughly with the right tools, and communicate clearly sets a higher standard. It's not just about brushing out tubes—it's about delivering long-term performance and reliability.