The leak detection job from hell....

Mark Eatherton

Wallies, As most of you know, I've been chasing leaks with infrared and doppler technologies for about 30 years. I was asked to locate a leak in a building that was originally built as an apartment complex, and later converted to individual condominiums. This job started 5 months ago, and just ended Friday.



The system is a district heating system with one boiler that services three different buildings, with the S&R lines being run in copper. The "leak" actually showed up in an electrical box before I got there. They'd hired numerous plumbers, and one guy who was injecting helium into the lines and using a sniffer to detect the gas and leak.



By the time I got there, they had broken the electrical conduit at the floor level in order to keep water out of the circuit breaker box, and had jack hammered up the floor of one unit, to no avail. When I got there, I had to start where the obvious signs were (leaking water) and work my way backwards from there. THe big stumper was that the water coming out of the conduit was only 70 degrees F, and it was being heated by the CFT boiler to 180 degrees F.... Hmmm I searched with the Infrared camera until I was blue in the face, to no avail in the unit that the leaks was actually showing. FIrst time I've EVER seen water running out of a conduit, and hopefully the last.



So, we start looking for the second obvious signs of hot water leakage, which is extremely warm apartments. We were aware of three units that complained of excess heat. The first one was where they had already done jack hammer exploratory surgery to no avail. I was above to do a hydraulic test to confirm circuit integrity on that unit so we didn't have to make another un-needed mess.



The second unit was a bank owned walk away unit, and it WAS extremely HOT in the unit, like 90 degrees F wit the thermostat completely off. I was unable to perform a hydro stat test on it due to failing gate valves, but when viewed thru the eyes of the IR camera, there was no evidence of "pooling" associated with a below grade leak. I was able to get one of three isolation valves (one supply, two returns) closed, and got hat unit to cool down, and felt fairly comfortable that the leak wasn't in that unit. Seems someone had replaced their existing pump with a much larger Grundfos wet rotored pump, and it was causing the zone valve in this unit to bypass.



THe last known suspect was the end unit where the 2" copper lines came up out of the ground. We cut the wall open and installed 2 each 2" ball valves to confirm or deny piping integrity between the heat source building and the suspected leak building. Here's where it gets even tricker, because when we closed the new isolation ball valves on the 2" mains, the pressure held indicating that the lines between the two buildings were OK...



So, at this point I had completely exhausted the Inrared imager as my favorite and primary means of leak detection. I had to call an associate of mine in with a Doppler Leak Co-relator system. We started from scratch, working our way through the suspected leaking building, to no avail. The doppler kept telling us that the leak was behind the receiving unit. Ends up we should have listened to it, and not the president of the HOA board who kept pointing us back towards where the water was running out of the building...



Eventually, out of frustration, the president decided he needed a break from leak sleuthing (against our recommendations, because the noise coming from the PRV was SIGNIFICANT). I reminded him that ignoring this leak would cause additional component failure (we had to replace the Grundfos pump) and that we wanted to put this project in our rear view mirror...



He finally relented and let me back in. THis time, I started on the end of the building where the leak was "showing", and using a contact microphone listened to the leak based on percentage of noise. As I worked my way back towards the mechanical room, the noise got louder. This time, when I closed the two 2" isolation valves we'd recently installed, the leak noise continued. HMMMmmm. How could THAT be?



In a leap of desperation, I grabbed my IR camera and went back to the heat source building. On my way there, I happened to look down into an exterior garden level porch of the unit that was right next to the boiler room, and what I saw almost knocked my eyes out. It was 30 degrees F OSA temperature, and the exposed concrete slab was running 100 degrees F... Now THAT will get your attention.



So, I arranged access in to that unit (require 24 hours advance unless it is a leaking water emergency) and when we walked into the unit, it was H O T . In fact, the son of the lady who lived there said it was so hot that the couldn't sit or lay on the floor.... He said that it was not uncommon to have their sliding glass door to the patio open, even when it was below zero outside... When asked why he hadn't complained, he said that they had, to the condo owner (they were renters) and the owners said that the heat was paid for and to not worry about it. Besides, their unit was always warmer than usual due to the fact that it was right next to the mechanical room. When we put the doppler on it, it told us EXACTLY where the leak was. We opened the floor, and found the leak (inside of a 45 degree el) and repaired it, and all water flow has stopped.



So, you may ask yourself, why was water running out of electrical conduits? Because the heat source building sits about 8' higher than where the water was running out of the conduit, and the conduit was in the same trench as the 2" supply and return lines going to the "leak" building.



And then you may ask, "Why did the quick fill hydrostatic test between the two buildings "pass" ?"



The crack in the 45 degree fitting was in such a place, that when the pipe was hot and expanded, the crack was bigger. The pipe had cooled down while we drained the building and had contracted the crack closed, hence a false positive test result. When the pipe heated back up, it started leaking again.



All's well that ends well, and I guess the lesson learned here is to trust technology more than your (and others) gut feelings. Just because there's water, doesn't necessarily mean that there is a leak near by... Especially when its running out of an electrical conduit.



Next problem please... :-)



ME

Steamhead

Nice work!

how many pumps did it eat up? 

STEVEusaPA

nice job...

Sounds aggravating, that's why you deserve the big bucks .

When you said water coming out of conduit, for some reason I immediately thought of a Three Stooges short (when they were plumbers), "hey Moe, there's wires in these pipes".

Steve Whitbeck

Nice work

A few years ago I had a FRIEND with a inconsistant freon leak in his house A/C.

I added freon in the spring and and two weeks later had to add it again. checked all brazed connections with a sniffer and soap. Added dye to the system. Month and a half went by and no problems. ( warm spring - cool summer ) Next spring everything is fine two weeks later again it is low. Thought it might be kids huffing so I put seal caps on. still leaked out in one week. earlier I had isolated the evap coil and line set and pressure tested it to as much as 400 PSI sith nitrogen. Two days - NO presssure loss.

Got mad and pressurized the whole system to 400 PSI with nitrogen - NO LEAKS.. Held full pressure.  On blowing down the nitrogen I opened the guages outside and wnet inside to button up the coil box.  As the system pressure wnt lower than 60 PSI the evap coil started to leak badly. ( I could hear it )

The darn thing wouldn't leak unless the suction pressure was less than 60 PSI.

In other words it wouldn't leak unless it was running.

The summer before was cool toward the end of wummer so it didn't run - so it didn't leak. And it didn't leak all winter.

Replaced the coil - problem solved.

Mark Eatherton

Thanks Frank and Steve...

They only had to replace one of those, and a make up PRV, but that stung them to the tune of $3K.



Now the boiler headers are leaking, but they were slated for replacement any way.



I am really glad this one is in my rear view mirror :-)



ME

Gordan

Thermal expansion?

If the crack was in such a place that it opened up as the piping heated up, could it be that there were inadequate provisions for thermal expansion and that it's only a matter of time before the new elbow cracks as well?

Mark Eatherton

It was NOT hydraulic erosion corrosion...

That would have been on the outside of the fitting.



I was not hired to diagnose reason for failure, only to locate and eliminate the leak. The pipe lasted for 40 years as it was.



As I said, the "common" trench had the conduits for 12 units plus the house power requirements on TOP of the 2" copper lines.



In order to facilitate a U shaped expansion joint, it would have required removal of and replacement of all of the conduit and wires (impossible to do without having to place illegal junction boxes below the concrete floor, or break up a whole lot of concrete) and displacing that many people into a hotel would have bankrupt the HOA.



As it was, the PVC conduits were so close to the failed joint that silver soldering was not an option without creating another smoke/fire hazard. We opted to use a ProPress fittings instead.



Did I mention that it was cold and snowing outside at the time?



Once the new boilers are in place, the extreme expansion/contraction issues will be negated due to flat curve ODR. (apartments are way over radiated).



One has to choose their battles carefully, and take into consideration the economic viability of their customer.



(EDIT note; I added the word NOT to the title on this post. That's what happens if I type before the second cup of joe in the morning;-))



ME

Steve_210

Where

Can I find more info on the Doppler system

Mark Eatherton

UTSI...

The company I use is called Utility Technical Services Inc. This is ALL he does, and he does it for many small utilities. The owners name is Dave Anderson, and he is also a dealer for the Doppler Leak Co-relating equipment.



http://www.utsleak.com/



The equipment he uses has three components. 2 each transmitting/listening devices and one co-relator. He places one transmitter on each end of the suspected leaking pipe, and they listen to the leak, and send signals to the co-relator and tells him to the foot where the leak is located. What it CAN'T do, is tell you where the pipe is, so you need to provide that information, because having one without the other is virtually useless.



One has to use these service after having exhausted all other resources, because they are not inexpensive. In this particular situation, the leak had been going on for SOO long, that the slab was a consistent glowing orange ember, with no discernible difference in temperature to show where the leak was occurring. I could have run cold water through the leak and looked for the cold spot, but inasmuch as we were fairly certain of the pipes locations, and needed to get it fixed sooner rather than later, I opted to use the Doppler system, and it was dead nuts on.



Generally speaking, if I have good and total control over the system (which in this case I did NOT) I depend on the IR system to locate the leak, and back it up with a pipe contact microphone that allows me to "listen" for the leak, if it is near.



Thanks for asking.



ME

kcopp

This is just one ...

 reason why district heating is not such a good idea. Nice find. There are some really strange people out there...

Mark Eatherton

People are pigs....

In order to do a proper job of an infrared floor survey, EVERYTHING must be picked up off the floor. We'd give these people 1 weeks advanced notice, and when we'd show up, the floor was COVERED with clothes, dirty diapers, trash, food... Pigs, I'm telling you.



So, then, I would have to pick up all their "stuff" and move it from one side of the room, roll back the carpet, do the survey, then move it to the other side of the room, and survey the other. Then, what does one do with all these piles of "stuff"?



I don't like working in peoples personal space. Give me a nice dirty mechanical room any day of the week...



As for district heating systems, I think if they are done right (super insulated below grade to negate standby losses) and it is monitored by means of a makeup water meter, they can be just fine. The cost of the physical plant is amortized over a greater area, creating a lower cost per square foot than having individual physical plants. The BAD thing about them, is if a major component fails (pump, boiler, etc) then EVERYONE suffers.



Plusses and minuses on both sides of the thought.



ME

SWEI

district heat

Sure makes sense in some locales, ditto for cooling (check out the deep lake cooling system in downtown Toronto.)



I'm looking at several projects where it might make a LOT of sense for a group of small houses.  Mod/cons just don't come small enough for well-built little houses but if you group a few together, the math starts to look very attractive.  Throw in a solar thermal collector or two on each building, dump the excess back into the loop and it gets rather interesting.

kcopp

It just seems kind....

odd to go that way. I don't get the thought process. We as a trade go to a big building and see 1 very large boiler be it gas or oil to be replaced. The prevailing thought these days is "Hey pipe it primary secondary using 3 boilers instead of one"... we all know the advantages of that... Now put that up against District heating where for some reason some are using the exact opposite thought process to heat a bunch of buildings w/ just 1 big boiler. How is that supposed to be better or a step forward?

Jean-David Beyer

If the great big boiler used to supply many buildings ...

... had to be there anyway -- perhaps it ran the steam turbine for a power company -- the steam at the final output from the turbine might well be hot enough to heat those buildings, and if it were not for those buildings, they would need a bigger condenser to convert the waste steam back to hot water to put back into the boiler. Those boilers seem to be water tube boilers these days.



So they should be able to supply waste steam at very low cost, since it is there anyway.

Mad Dog_2

Nice job M.E.!

Paydirt!  Even when you are getting  T & M for those jobs...the pressure is on because they see the $$$$ signs adding up: :"......How we doin????  think your gonna find it soon???????"     Mad Dog

heatpro02920

I can honestly say

I never worked on anything that big... I remember reading this post when it was new, thinking, where would I start...



I do small stuff but have great luck with the thermal imagers, in something that big, I would need access to everything all at once so we could trace everything and follow the energy..



This winter I went to a call where they had a radiant slab and could hear the water feed "vibrating" non stop, luckily they were smart enough to know it was a new noise and call someone in {a friend of mines company}, they jack hammered the floor in 2 spots and had no luck, I went with the TI camera and found it in 4 minutes, about 25 feet away from the closest spot they jackhammered... this has happened a few times, that camera is worth its weight...

Mark Eatherton

Hey Matt...

Busier than I've ever been in my whole life. Hope you're doing well as well. We should finish your driveway solar system some day.



How's the new job going?I



Thought about you whilst in NYC at the Taco shindig in January. Me and Der Heatmeister ran into JohnNY and his lovely wife.



Drop me an email when you want to finish up your system. It'd make a great candidate for the RPA System design showcase Awards, and could possibly start a revolution.



We did find and fix the leak. If property management had listened to the occupants, and told me what they'd been saying, this job would have been much easier to do...



ME

A.J.

Side question

NICE JOB Mark.

I've been thinking about adding an IR camera to my tool box, which one do you use and do you like it ?

Thanks A.J.

Bob Harper

take away fact

If you read Mark's case carefully, you'll note the static hydrostat test gave a false positive. How is this? Because much testing is done static and not dynamic meaning under the conditions of use. Things act differently when heated/ cooled, etc. That's one thing working in forensics and an R&D test lab taught me.



Good catch Mark and a good lesson in persistence and listening to that little bird sitting on your shoulder.

Mark Eatherton

Fluke Ti series

I paid around 5 k for mine. You can get them for around 1 k, but be aware of screen size, pixel density etc. I think a real good universal one would take around 3 k from your beer fund. Most reps will let you borrow one for a few days to check it out.



ME

Mark Eatherton

Thanks Bob...

This job had me working and thinking in circles. Glad I finally got out of the loop.



ME

A.J.

THANKS

Thanks Mark

That was a very nice piece of trouble shooting specially after it held a pressure test . That would have have me going nuts.

A.J.

RobG

Question?

Not to take away from ME's praise  but how did this post get recycled? I remember it from 2012 but when it first popped up recently there was no new post attached to it until Mad Dog's? 



Inquiring minds want to know,

Rob

Mark Eatherton

Man bot...

Rob, someone re-opened it last week and was trying to advertise something or something. I'm sure Dan yanked his obvious advertising post, and this stayed up.



ME