I have a question. I had a nursing home call me today regarding an infrared scan of the slab of their building. They are experiencing problems with water pressure. Before I take the job, is there anything I need to be aware of about scanning a concrete slab?
What is going to be your method of obtaining and the temperature difference of the slab and waterlines?
This will be the first time I have scanned a slab before. The pipes are under the slab. but he doesn’t know where they are under the slab. There is no plumbing diagram. What is the best method for obtaining the temperature difference. How much of a difference will be needed? I thought about having him have the heat on in the building to 80 degrees or so, but I have to consider the residents. I thought about using an electric heater in each room, but I don’t know if that will make much of a difference over a short term
Going to depend on a lot of things do the floors have carpet over the slab or or they tiled. Is there any visible water on the exterior of the foundaion has it come to the surface anywhere on the exterior. 0ne needs close to a 10 degree Delta T between the face of the concrete and any water flow beneath it. If the leak is small not very likely to pin point there is going to have to be enough water under the slab to cool it
Yeah, I know. I asked him those same questions. Some areas are tiled, some are carpeted. There is no water present on the exterior. He is not even sure if that is the problem. He just stated over the last week they have had a drop in water pressure. It could be something with the piping between the building and the street.
I haven’t specifically searched for this, in fact I turned one down a few weeks ago because I was not sure I could find the leak. In theory you should be able to, but in practice I am not certain, given all of the different variables.
From use in lots of inspection in homes with slabs (95% of what I do), I find that I see the hot water lines sometimes when I run a fixture long enough. Not sure I can definatively say I have been able to see the cold water lines. I have also found that the hot lines tend to show up more in homes with a recirc pump.
I am interested in what others have done with this.
You need to do a little plumbing to do this correct. hook up the cold water pipes up to the hot water heater. drop the temp in the building as cold as you can get it. then turn the hot water heater up as hot as you can get it. then the run the hot water to all cold pipes and to any out side bib. as the hot water runs do your scan.
I have done this it works very well.:mrgreen:
Boy that could be a pain, but it’s really the best way to do it.
Would it be possible to pressure test the system?
That just won’t be feasible for me to do for this client. If it were residential that would be one thing, but a large commercial job is something completely different.
Pressure test sounds good.
ok, I am showing my ignorance. How would I go about doing a pressure test to find the potential leak under the slab?
I think you should pass on this one…
There is a lot more to consider aside from the IR stuff that must be addressed first.
Basic plumbing stuff…
Pressurize the lines with air, which leaks faster than liquid would be a start.
Whenever I go out on moisture intrusion or leak detection/isolation work. I make it perfectly clear IR may not be the do all, end all inspection technique and may be inconclusive. I also agree up front to charge only for the trip in the event the equipment I bring and I are unable to perform to their expectations. This helps to earn client respect and more times than not I’ve been able to find something they were unaware of. Making them happy to pay full fee for the inspection…we’ll never know unless we go
Better yet, make sure all fixtures are turned off in the structure, then check the meter. If the red triangle is spinning, you’ve probably got a leak.
BTW, I am not a plumber, but did stay at the Holiday Inn Express last night with these 3 guys claiming to be auto execs!!