maintenance and leak testing of crimped joint systems

Maintenance and regular leak testing of crimped joint systems is a key factor for the long-term durability of the entire heating system, yet it is often neglected until the first problems appear. A properly installed system using high-quality components such as PRESS 90° elbow or PRESS T-piece forms a solid foundation, but without subsequent inspection and maintenance, even the best material will not fulfill its function to 100%.

Visual inspection and joint diagnostics

The first step in maintenance is a thorough visual inspection of all visible crimped joints in the system, looking for signs of corrosion, mechanical damage or moisture on the walls around the fitting. An experienced technician can often identify problems just by looking at surface color changes in the metal or sediment traces that indicate a slow water leak, allowing the issue to be localized before it causes significant damage to tiles or flooring.

This process also includes checking sealing elements, which can degrade over time due to thermal expansion or chemical substances in hot water, a common occurrence in older installations where, for example, PRESS inserts are used to connect radiators. If you notice any suspicious changes, immediately perform a pressure test on the affected section, as even a minor fault can lead to significant water damage if not detected in time.

Pressure test parameters and monitoring

Professional maintenance necessarily includes regular pressure tests, which verify the integrity of the entire system under operating and elevated pressure, with the target value being 1.5 times higher than the maximum operating pressure, usually around 6 bar for standard home heating. A pressure test lasts at least 24 hours, during which pressure drop on the manometer must be monitored, and any drop outside the thermal expansion tolerance indicates a leak in one of the crimped joints.

• Before the test, ensure the system is completely filled with water and de-aerated of air bubbles.
• Record the initial pressure and water temperature so you can later adjust the values according to temperature differences.
• Check the pressure every 2-3 hours and record any fluctuations in the installation technical log.
• After the test, carefully release the excess pressure and inspect all visible joints to ensure they are not wet.

In practice, we have encountered a case where a small leak appeared at a PEX 17 mm joint after two years, which was not detected during the standard 24-hour test because it only occurred during fluctuating temperatures and pressures in the winter period, when water expands and contracts. Regular checks with precise pressure measurements in different seasons therefore allow problems to be detected before they become critical.

Identification of common causes of leaks

The most common cause of leaks in crimped systems is not the crimping tool itself, but improper pipe preparation, specifically scratches on the surface of the PEX pipe or dirt on the internal thread of the fitting, which disrupt the sealing ring. If a deep scratch is present on the pipe surface, the crimping ring cannot fully compensate for it, creating a microscopic gap that expands over time and causes a water leak.

The second significant cause is an unsuitable crimping tool, which does not provide sufficient force to properly compress the ring, or conversely, excessive force that deforms the fitting body and damages the sealing material. In such cases, it is often necessary to replace the entire joint, as repairing a damaged crimp is not possible and safe operation is not feasible without replacing the components.

Another common problem is thermal expansion, which causes joints to loosen during sudden temperature changes, especially if suitable expansion joints are missing or if the pipes are rigidly fixed without the possibility of movement. When installing systems with long pipe sections, it is therefore essential to account for the fact that they will expand and contract, and thus it is necessary to maintain proper distances between fastenings and use flexible joints.

Means and procedures for preventive maintenance

To effectively maintain crimped systems, it is necessary to use specialized tools such as digital crimping pliers with calibration sensors, which automatically verify that the correct crimping level has been achieved, thus eliminating the human factor in handling the tool. These modern tools have built-in memory chips that record each crimping process and allow subsequent analysis, which is invaluable for warranties and installation quality checks.

• Use only original crimping dies intended for a specific type of fitting and pipe diameter.
• Regularly check the condition of batteries in electronic crimping pliers to prevent interruption of the process during crimping.
• Maintain a clean work area and remove all dirt that could get into the connections during assembly.
• Always verify that the crimp ring is correctly positioned on the fitting body before the actual crimping.

A practical example from our practice is a situation where a customer used old crimping pliers without calibration for a new PEX pipe installation, which resulted in 30% of the connections not being sufficiently tightened and leaks appearing after the first system filling. After replacing them with new digital pliers and thoroughly checking all connections, the system stabilized and has been operating without problems for several years.

Repair and replacement of leaky connections

If a leak is detected in a crimped connection, the only safe method of repair is complete disassembly and replacement of the entire crimped section, including the pipe section and a new fitting, because a crimped connection cannot be repaired by tightening or adding sealing material. Before starting repairs, it is necessary to drain the water from the system, disconnect the heat source, and ensure that the work is carried out in a dry and clean environment to prevent further contamination of the new parts.

It is important not to forget that after replacing the connections, it is necessary to perform a pressure test of the entire system, not just the new section, to ensure that the repair did not affect other parts of the installation and that the new connection is completely tight. This procedure is essential even if it is a small repair, as a change in system pressure can affect other, previously tight connections.

Diagnosis using thermography and ultrasonics

Along with visual inspection and pressure tests, it is essential in modern technical practice to use advanced diagnostic methods such as thermographic imaging or ultrasonic leak detection, which can identify problems even before they become visible.

Common questions

When is the first tightness test of a new system necessary?

The first tightness test must be carried out immediately after installation and before embedding the pipes into plaster or flooring, and this test should last at least 24 hours under operating pressure.

Can a crimped connection loosen on its own over time?

A crimped connection is designed to be permanent and should not loosen on its own if it was properly executed and high-quality materials were used, but thermal expansion can cause problems if the system is not properly dimensioned.

How to determine whether the problem is in the crimped connection or elsewhere?

A problem in a crimped connection is usually detected by local moisture or corrosion traces directly at the connection, while other problems may manifest as a general pressure drop in the entire system without visible moisture traces at one location.

To conclude, it is important to emphasize that maintenance and inspection of crimped systems are simpler and cheaper than subsequent repairs of major water damage, so it is essential to carry out regular checks and use only high-quality components and tools. An investment in professional installation and regular maintenance always pays off in the form of long-term system functionality and peace of mind without fear of unexpected water leaks.

Do you have a question about this topic?

Not sure or dealing with a specific situation in your home? Write to us - we are happy to help.