HVAC Journeyman Practice Exam

Which sealing is recommended for hydronic copper tube joints under a concrete slab?

1. Tape sealing

2. Heat sealing

3. Brazed sealing

4. Weld sealing

The correct answer is: Brazed sealing

The recommended method for sealing hydronic copper tube joints under a concrete slab is brazed sealing. This technique involves joining two pieces of metal by melting a filler metal into the joint, which creates a strong, durable bond. When hydronic systems are embedded in concrete, it's crucial to ensure that the joints are secure and leak-proof due to the potential difficulties in accessing them later for repairs. Brazing provides a robust connection that can withstand the environmental conditions typically present in concrete slabs, such as changes in temperature and potential movement within the concrete. Additionally, brazed joints are less likely to fail under pressure compared to other sealing methods, ensuring the longevity and reliability of the hydronic system. Other methods, such as heat sealing or tape sealing, may not provide the same level of integrity required for high-pressure applications or for long-term permanence. Welding is generally more applicable to non-copper materials or requires specific circumstances that favor its use over brazing. Thus, brazing is the preferred choice for ensuring reliable, leak-free hydronic connections in these challenging environments.