This month’s column is a continuation of my June column about a mysterious leak in a condo complex. Read on to find out more about the mystery...

Moving forward, we had become fairly confident that the leak was not inside of this particular building and suspected the possibility of the leak being underground between the two buildings. We decided to install isolation ball valves in the mains between the heat generating building and the suspect building.

This required a complete shutdown of the system and draining it to lower the water level to allow us to install the two sweat style ball valves on the copper mains. After the mains entered the suspect building, the mains then ran through the ceilings of the garden-level apartments, which was good because it eliminated that much more piping from being suspected of leaking. It took about four hours to drain, install valves and refill the system with cold water. We closed the ball valves, isolated the expansion tank to avoid unintended pressurization and re-pressurized the system with cold water, and the makeup valve servicing the system did not appear to be passing water, indicating to us that the leak was not between the boiler building and the suspect building that the leak was physically showing up at.

This caused me to scratch my head. We had fired the boilers to heat up the other two buildings that were on the loop, and when we turned the hot water loose to the suspect building again, the pressure reducing valve started screaming again, indicating that the leak was in the suspect building. At this point, I felt I had exhausted the ability to locate the leak using what I consider the most reliable means of leaks detection, that being my infrared imaging camera. I was going to have to resort to alternative technologies that being the Doppler leak detection that has been addressed in previous articles.

I called my one and only Doppler leak detection company and told the owner of my predicament. He said that the project sounded familiar, and agreed to meet me on site for a review of what I had done. When he showed up at the jobsite, he told me that he had been there about a year earlier, and had attempted to locate the leak using helium and could not find anything. He said that due to the fact that no one knew where or how the heating lines were run under the concrete, they had not even attempted to use the Doppler leak co-relator system to find the leak. With my infrared imager, I was able to show him exactly where the lines were located, so we had to start all over again, going to the furthest unit away from the mechanical room where the water was showing on the floor, and working our way backwards to the mechanical room.

Again, we had to notify the residents of our need to once again invade their privacy in our efforts to track down this wiley rogue leak. As we worked our way through the building, the Doppler unit kept telling us that the leak was up stream of the location we were testing, which didn’t make sense, because we’d performed a basic isolation hydrostatic test and determined through this testing that the lines between the two buildings did not appear to be the source of the leak, or so we thought. Basically, we found ourselves back at ground zero, scratching our heads, wondering where the heck the leak might be.

At this point, I thought that there was a possibility of having more than one leak in the system. I had seen jobs before where a plumber with good intentions had installed a float type automatic air vent on a heating system and had piped the tail piece of the auto vent  to a plumbing drain just in case the automatic air vent decided to leak, which they are prone to do. I once again had to notify a whole new set of residents on the upper floor that I needed to inspect their systems to eliminate the possibility of a leaking auto air vent. I gained access to the upper units, and unfortunately did not find any of the suspected automatic air vents with tail pieces. Back to ground zero.

Tune in next month as we continue our search for the elusive leak. Until then, happy hydronic leak busting!

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