The leak detection job from hell — Part 4

This month’s column is a continuation of my July column, and the last in the series about a mysterious leak in a condo complex. Read on to find out more about the final resolution.

This month’s column is a continuation of my July column, and the last in the series about a mysterious leak in a condo complex. Read on to find out more about the final resolution.

At this point, I felt I had exhausted all possible leak detection resources including infrared imaging inspection, ground contact microphones and Doppler leak detection system. I had promised the board of directors that I would find the leak, and found myself questioning my manners and methodology. I was running everything through my mind, trying to determine where the leak could possibly be. I had pretty much given up on trying to locate the leak, and was beginning the process in my mind of putting together a distribution system replacement program, and was surveying the property with my eyes, and was walking around the exterior of the building looking for a route manner and method. I happened to have my infrared imaging camera with me, still looking for some trace of heat on the exterior of the suspect building. As I was standing near the building that held the boiler, I just happened to glance at the patio concrete of a garden level apartment that was next to the boiler room, and much to my surprise, I saw a slab temperature of 100°F. The surrounding ambient temperature was around 30°F, so this was definitely not a fluke.

I arranged to gain access to the unit with the hot slab. Upon entry, the heat was overwhelming and stifling. I asked the resident (a renter, not an owner) if it was always this hot in the unit and he said that in the two years that they had lived there, that in order to remain comfortable, that they had to keep their sliding glass door open, even when it was zero degrees outside. When I asked him if he’d ever complained to anyone about the excess heat, he said that they had complained to the landlord, and that the landlord told him that the wall of his unit adjoined the boiler room, and that it was always hot in that unit, and that besides, their heat was included in the rental fee and that they shouldn’t worry about it.

The apartment was so hot that I couldn’t depend on my infrared imager to locate the leak, and had to once again call my Doppler detective to the case. We were able to determine exactly where the leak was located, linear footage wise, but could not determine the piping route due to the overwhelming heat. We instead had to depend upon the ground contact microphone to locate the area of the highest percentage of leak noise, which can be fairly tricky, but is better than nothing. We moved in two days later and began doing the jack hammer surgery. The first penetration of the slab gave the chisel back wet. Eureka! We were on top of the leak. Further surgery found that the 2-in. copper mains were on the bottom of the trench, and that the electrical conduits had been placed on top of the 2-in. copper lines. The leak was actually on the inside of a 45°F fitting, and appeared to be caused by stress associated with thermal expansion and contraction. We now knew why it was that there was water running out of the electrical conduit. The CPVC pipes had not been primed, only glued. Remember that this work was done roughly 40 years ago, and the code has since changed. The only good thing to come out of this project, other than obviously stopping the leak, is that it showed me numerous flaws in my methodology of leak sleuthing that you the reader can learn from.

First off, in a setting like this where there are a lot of people involved, including residents, owners, renters and boards of directors, a survey should be put out that asks obvious questions of the buildings occupants and the offsite owners that will lead you to the area nearest the location of the leak.

Ask if their apartment ever over heats. Bear in mind the possibility of failed zone valves, and/or bypassing zone valves.

Ask if the occupants have ever noticed any particular hot spots in the floor of their units that doesn’t seem to change with the changes in warmer weather. As zones stop calling for heat during the shoulder seasons, the flow of water inside the heating pipes would be less, and the radiant effects of pipe loss also less, unless a leak is present.

Ask if they have ever heard any hissing, like water leaking from a pipe. The resident of this unit said he had trouble getting to sleep at night because of the noise and heat.

Ask if they have noticed any excess condensation on exterior windows during cold weather. The residents of this unit said that they had a bag of old used bath towels that they kept on hand to put on the window sills to sop up the condensation that rolled off of the windows any time that it got cold outside. This is a key factor in getting close to the location of the leak, and is so obvious, that it is commonly overlooked in the process of trying to locate the leak.

Early in the discovery phase of this project, we were told by one of the board members, a licensed electrical engineer, that he had determined that the electrical lines were not run through the core of the building, but instead were run in a separate trench outside of the building. This caused partial confusion on our part, because the water was running out of an electrical conduit, and his statement didn’t make any sense based on what we were seeing in the field.

Another issue that caused confusion was the hydrostatic fill test that we had done on the 2-in. lines between the building with the heat source in it, and the building with the leak. I have since decided that the reason that we got a false negative was because the pipe had cooled and contracted, thereby pinching off the fitting fracture, and giving the indication that the leak was not in that section of the line. Once the line was heated back up, it again began leaking as it was before, which caused additional confusion. As I have said before, the only common denominator of all of the leaks I’ve had to track down over the years is that water is being wasted.

Tune in next month as we look at the unintended consequences of water and energy conservation efforts. Until then, happy record busting heat wave hydronicing!

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