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This is definitely more of a diagnostic repair question than a green building question but I think you all might like the challenge.

DavidFleuchaus | Posted in Mechanicals on

I co-own an energy efficiency contracting company and am used to using an IR camera for diagnosis of sources of air infiltration. I have a HW Boiler distribution pipe system located on top of a slab with 1-4(?) leaks. I took all the radiators out of the loop and then I repaired 2 leaks found by sound after pressurizing the system with air and but the rest of the leaks remain elusive. We used an ultra-sonic leak detector and identified one more potential leak but I don’t want to start digging under the oak flooring without confirmation and identification of other leaks. I scratched my head over this one for a couple weeks and came up with a solution…but it didn’t work… yet. First I heated the house with space heaters. Then I waited for a cold day and pressurized the system with cold air from a large air compressor placed outside. Perhaps the air needed to flow longer for the temp difference to show up on my IR camera as the cold air affected the building materials around the leak, therefore, I might let the compressor run for 6 or 12 or 24 hours and look for leaks then. The house is half occupied and half vacant. Another option is inserting a scent into the system and try to identify the leak that way but the floor is tongue and groove and the walls and ceiling are 3/4″plaster over drywall. It would be tough to find the initial leak points that way. Of course I could blow hot water through but that would be a last resort and that method would still not necessarily isolate the source of each leak. Any thoughts? (Re-use is green, right?)

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  1. GBA Editor
    Martin Holladay | | #1

    As far as I know, when an infrared camera is used to detect leaks in hydronic tubing (usually part of a radiant floor heating system), the usual method is to circulate hot water through the tubing. There are lots of documents and videos on the web that discuss this technique:

    I imagine that these techniques were covered when you took your multi-day training session in how to use your thermal imaging equipment. (You did remember to sign up for that course, didn't you?)

  2. wjrobinson | | #2

    4 leaks.... time to abandon ship. I would stop using the floor system or sell. 4 leaks today, how many more in the future?

  3. user-665956 | | #3

    Thank you for your responses.
    I waited for a cold day, put the air compressor outside @ 10 degrees F, inside temp 75F, and waited for hours but my IR camera still couldn't reveal the few small remaining leaks. I then pushed the PSI to 80, and listened carefully. I found one leak between ceiling and floor - a union that somehow got a bit loose. Easy to fix. I also noticed 2 small leaks at the drainage faucets so I will cap these or replace the gaskets. The current PSI loss before capping drainage faucets is 1-1.5 lb../20 minutes. I think that is small enough to stop the hunt, fill the system with hot water and check for leaks with the IR camera after first installing all the radiators and fittings.
    As for the risk of future leaks, so far there was only one leak from a corroded pipe. The rest were from a few fittings and gaskets. So I'm still willing to risk it. Given the alternatives it is worth it. My IR skills are most probably up to the task.

  4. davidmeiland | | #4

    My opinion as an IR user... it is unlikely that you will find pinhole leaks using hot water in a piping system like you describe. I would stick with pressurized air and get a stethoscope to aid in finding the leaks.

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