The leak detection job from hell

May 1, 2012
The very first question that was asked of me was whether or not I had the ability to find a leak. I answered positively, telling them that if there was a leak to be found, that I could find it.

I received a call from a friend of mine who is in the energy conservation field. He had gotten involved with a local condominium homeowners association who was interested in conserving energy in their condo complex. My friend is very well versed on building science as it pertains to energy conservation, but when it comes to boilers, he knows when to back out of the boiler room door and call me for advice. He said he heard things going on inside of this boiler room that just didn’t sound right and thought I should be called in to take a look. We scheduled a meeting with himself, the president and vice president of the home owners association on site.

The very first question that was asked of me was whether or not I had the ability to find a leak. I answered positively, telling them that if there was a leak to be found, that I could find it. They then took me to the farthest apartment away from the physical plants location, in a remote building. This was an early district heating system. The boiler was in one building, and had underground copper water lines that went to two other buildings. This group of buildings was originally built in the 1970s and served as an apartment complex for many years before being purchased and converted to condominiums, and sold to individuals.

As we entered the end unit, which is 200 feet away from the boiler/heat source, I noticed a trickle of water running across the floor to a floor drain that serviced the exterior garden level porch. As we rounded the corner to go into the bedroom, much to my surprise, I saw that the water was running out of a 1-in. piece of CPVC conduit that was providing the main power to this unit’s electrical panel. The fitting had been broken off at the floor level. This was done in an effort to keep the water from accumulating in the bottom of the electrical panel which was about 48-in. above the floor. This was a new one on me. In my 36 years of chasing leaks, I have never seen water trickling out of an electrical conduit. I should point out to my newer readers that I have written numerous articles on the art of leak detection.

As I have previously pointed out, in doing leak detection, one has to follow the obvious signs before resorting to technology in an effort to fine tune the area in which to apply these technologies. In this case, the most obvious sign was the water trickling across the floor. However, there was one slight looming problem. The boiler heating system was being maintained at 180°F, and the water trickling out of the PVC conduit was only 70°F. Nothing like having an interesting curve thrown into the mix. My thoughts at this point were that this leak was actually occurring a long ways away, and allowing the water to cool off to room temperature before it became evident, or it was being caused by a potable water (cold) leak. I have seen situations whereby a plastic drain stack was in constant contact with a ½-in. copper water line, and the regular expansion/contraction of the ABS plastic pipe was enough to abrade a hole though the copper water line. I had all kinds of things going through my head at this point, but I knew that having water running out of a live electrical conduit was not a good thing to have to deal with.

Back to sleuthing ... If the first level of detection (water on the floor) doesn’t lead you to the leak, then a person has to go to the next obvious sign, that being elevated unwanted temperature in individual units. This heating system had recently received a circulator replacement because the original pump had failed, probably due to excess makeup water. One (wrongly) has to assume that the person/company that replaced the pump at least attempted to match the performance curve of the existing pump with the curve of the replacement pump. I suddenly realized, that assumptions can be wrong, and will come back to bite you. There were numerous units that were over heating within the complex. So much in fact that in some cases, the amount of saturated heat made it virtually impossible to utilize my thermal infrared imaging camera to look for a hot spot.

I should mention that the means of heat distribution was hot water baseboard, with the heating lines were run under the concrete on grade floors, creating many opportunities for leakage. All I could see in this overheating garden level apartments was one large blob of orange hot surfaces. One unit was consistently at 80°F. This unit had been abandoned by the previous owner and was in receivership by the bank that had financed it, so it was empty. No one home to complain about the excess heat.

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