Just across the border from San Diego sits an engineering problem worth solving. La Hacienda orphanage in Tijuana couldn't provide basic hot water for cooking, cleaning, or showers lasting more than 2 minutes. Previous UCSD teams had tried installing a solar water heating system, but pipe failures had brought operations to a halt. Our team's goal was simple: get it working by end of quarter. The project history revealed a pattern of setbacks - pandemic delays, loss of key contacts, and most recently, a catastrophic pipe burst.

Our team came into the project with one goal in mind: get the system working by any means necessary.

Failure Analysis

To begin the repair, we first needed to figire out what went wrong to cause the system to break.

The ruptured PVC showed classic signs of breakdown:

• Surface chalking

• Color fading

• Material embrittlement All indicators pointed to prolonged sun exposure compromising structural integrity.

However, the real killer was probably the temperature. The system was sitting out in the Tijuana sun for months with no water running through it, likely exceeding the PVC's 140°F limit.

Upgrades

Recognizing the need for a more resilient solution, we spec’d out a complete upgrade to Schedule 80 CPVC pipes, known for their higher resistance to UV radiation and greater temperature tolerance to the harsh desert environment. We sourced parts mainly from McMaster and Amazon so they would be inexpensive and easy to replace later in case of any failures in the future.

Furthermore, we conducted a review of the Piping & Instrumentation Diagram (P&ID) and identified air locking as a potential failure mode in the original system, even though it likely did not contribute to the original failure. To mitigate the issue, we sourced and installed a float air release valve at the system’s high point. We took the opportunity to update the P&ID to reflect all of our changes.

Installation & Testing

After installing the new piping and control box, we flushed entire system using a specialized cleaning solution to remove any residues or blockages. We then pressure tested the system by running water through it during nighttime. The upgraded system performed effectively, with the new pipes withstanding the pressure without any signs of damage. We also installed a new control box that would allow us to monitor the system’s status from San Diego.

Results & Reflection

Building upon years of work on this project, we were finally able to get the solar water heating system up and running this quarter. We conducted a successful pressure test during the nighttime, and are ready to run the system during the day to confirm that the solar panel is effectively heating the water.

Engineering isn't always about building something new. Sometimes it's about understanding why something broke and implementing the right fix. In this case, that meant dozens of kids getting proper hot water. Hard to imagine a better use of thermodynamics and material science than that.