Subject: [HELP] Water Leakage at Home – Can’t Find the Source

[Sorama]

I had a leak detection company check my place and they used compressed nitrogen to inject into the pipes (drained of water). Then they used a microphone to listen for the leak.

As explained, the gas used is not 100% nitrogen, but a mixture of 95% nitrogen and 5% hydrogen.

As hydrogen is the lightest molecule, it finds its way straight up and goes through light concrete.
Then a sniffer is used to detect the hydrogen.

You can also use this gas when practicing acoustic detection, but that is a though waste of money, as you can do the same with an air compressor.

However, the combination of water and air (from the compressor) gives a rather easy to distinguish sound when going through a hole in a pipe.

But it takes years of experience to hear the difference.

[BILLPOD]

Good Morning Eassssse, First of all, welcome to the Forum.   I'm curious what would lead you to an electronics forum to seek advice for a plumbing problem?   If you wanted to find logical thinking minds, you did make a good choice, as you have, what I consider, some of the most logical, educated, and helpful minds of any forum on the internet.  A lot of good ideas have been given to you, but I believe you need to provide more information, in order to help narrow the problem, like the type of construction you have, and where the water supply pipe enters the building, and if the meter is remote from the building.  I especially like the idea of draining the entire system and filling it with compressed air.  I'm not a plumbing expert, but being a homeowner for over 50 years, and a DIYer, I've experienced quite a few plumbing problems, but the one that most closely resembles yours was a similar minute leak that eventually led me to a toilet flush valve.   Luckily, I had valves that would isolate various parts of my home.   Also, shut off the water going into your hot water tank, which should prove or eliminate the hot water piping.  Good luck, and be sure and post your eventual solution, and the method you used to track it down.

[BradC]

I especially like the idea of draining the entire system and filling it with compressed air.

I went this route initially. Drained the whole system and pressurized it. After the compressor had run for a *considerable* time it occurred to me I was also pressurizing my 270L hot water storage tank which would have gone off like an explosive and probably taken out part of the house had something gone wrong. Our water pressure is usually about 6 bar and I had 8 bar of air in the system.

Just be aware and don't do something potentially dumb like I did.

[Kasper]

a similar minute leak that eventually led me to a toilet flush valve.

This is my guess as well.

[golden_labels]

It would be great, if OP replied.

[Seekonk]

      sonic leak detector

[MrAl]

Hi everyone,

I know this forum is more about electronics, but I’ve seen a lot of practical and knowledgeable people here, so I hope it’s okay to ask for some off-topic help.

I’ve recently discovered a water leak somewhere in my home’s plumbing system, but I can’t figure out exactly where it’s coming from. There’s no obvious dripping or visible damage, but I can hear a faint sound of water flow even when all faucets are turned off. My water meter is also slowly spinning, which confirms there’s a leak.

Here’s what I’ve tried so far:

Turned off all water-using appliances and fixtures inside the house.

Checked under sinks, behind toilets, and around the water heater.

Walked around the house to listen for leaking sounds.

Monitored the water meter for signs of usage.

Unfortunately, nothing obvious is showing up, and I’m not sure whether the leak is under the floor, in the walls, or even outside underground.

Does anyone here have experience with this kind of issue or suggestions on how to locate a hidden leak? Any tips, tools, or diagnostic methods would be appreciated. I’m trying to avoid calling a plumber immediately if I can narrow it down a bit myself first.

Thanks in advance!

Best regards,
Eassssse

Hi,

Do you have hot water heating in your house?

Some, if not all, hot water systems have a direct connection to the cold water pipe in the home.  That means if the hot water pipes for the heating has a leak, it will draw more water from the cold-water pipe.  That would include radiator leaks where the cold water keeps flowing into the heating system.

Obviously if you have electric heating this would not happen.

No, heating system with radiators is not possible as it is a CLOSED system.

Are you sure about that?
I ask because hot water systems can loose water through various means so they often have a connection to the mains water line.  This is so new water can be added if there is a tiny leak or small loss somewhere.  If there is a larger leak, this can lead to a lot of water usage.

Here's a quote:
"Hot water heating systems, whether they are gas or electric, typically receive their water from the municipal water supply or a well. This cold water enters the water heater and is then heated by a burner or heating element. "

If yours really is closed then it is closed, but I wonder how you know that it is really completely closed.

[Sorama]

Hi everyone,

I know this forum is more about electronics, but I’ve seen a lot of practical and knowledgeable people here, so I hope it’s okay to ask for some off-topic help.

I’ve recently discovered a water leak somewhere in my home’s plumbing system, but I can’t figure out exactly where it’s coming from. There’s no obvious dripping or visible damage, but I can hear a faint sound of water flow even when all faucets are turned off. My water meter is also slowly spinning, which confirms there’s a leak.

Here’s what I’ve tried so far:

Turned off all water-using appliances and fixtures inside the house.

Checked under sinks, behind toilets, and around the water heater.

Walked around the house to listen for leaking sounds.

Monitored the water meter for signs of usage.

Unfortunately, nothing obvious is showing up, and I’m not sure whether the leak is under the floor, in the walls, or even outside underground.

Does anyone here have experience with this kind of issue or suggestions on how to locate a hidden leak? Any tips, tools, or diagnostic methods would be appreciated. I’m trying to avoid calling a plumber immediately if I can narrow it down a bit myself first.

Thanks in advance!

Best regards,
Eassssse

Hi,

Do you have hot water heating in your house?

Some, if not all, hot water systems have a direct connection to the cold water pipe in the home.  That means if the hot water pipes for the heating has a leak, it will draw more water from the cold-water pipe.  That would include radiator leaks where the cold water keeps flowing into the heating system.

Obviously if you have electric heating this would not happen.

No, heating system with radiators is not possible as it is a CLOSED system.

Are you sure about that?
I ask because hot water systems can loose water through various means so they often have a connection to the mains water line.  This is so new water can be added if there is a tiny leak or small loss somewhere.  If there is a larger leak, this can lead to a lot of water usage.

Here's a quote:
"Hot water heating systems, whether they are gas or electric, typically receive their water from the municipal water supply or a well. This cold water enters the water heater and is then heated by a burner or heating element. "

If yours really is closed then it is closed, but I wonder how you know that it is really completely closed.

you need to distinguish between hot water systems for consumption/washing and hot water for heating systems like radiators.

Heating systems are of course a closed loop because water does not disappear in the heating system (apart from some very minor evaporation).

Using (hot) water for consumption/washing is of course connected to the mains as the water that is used, is gone.

[John Coloccia]

Good Morning Eassssse, First of all, welcome to the Forum.   I'm curious what would lead you to an electronics forum to seek advice for a plumbing problem?

I'm surprised no one's suggested ripping out all the old-fashioned pipes, and just replace it with a micro.

Personally, once I check my toilets, heating system, water treatment and do a general walk around, I'm calling someone. I might get lucky and find it on my own, but a pro that's got a lot of experience and the right tools will find it quickly.

[SteveThackery]

Here in the UK we mostly use 'combi' boilers. The cold mains water flows through a heat exchanger in the boiler on its way to the taps. Thus, the hot water to the taps is at mains pressure.

The heating system is a closed loop and the water is directly heated in the boiler and pumped around the radiators. The boiler has a 'filling loop' which - when two valves are opened - connects the mains water to the closed heating circuit to add more water to it. The heating circuit has an expansion tank comprising a sealed vessel with a membrane down the middle. The heating circuit water is on one side of the membrane and air (or nitrogen) on the other. Water is added to the heating circuit via the filling loop until the pressure in the heating circuit reaches 1 to 1.5 bar, cold (typically).

If the heating circuit has a leak the pressure gradually falls, as revealed by the pressure gauge on the boiler. If it falls below 0.5 bar (typically) the boiler will cut out.

If the pressure in the heating circuit rises above 3 bar (typically) a pressure release valve opens and water is dumped into the condensate outlet pipe.

The expansion vessel has a limited life. When the diaphragm fails, the air is expelled and the vessel fills with water. Thus it is no longer able to "buffer" the pressure rise when the water in the heating circuit is heated. As a result the pressure rises quickly and - when it reaches 3 bar - begins to be expelled through the pressure release valve. When the heating system switches off, the pressure falls quickly (due to the lack of buffering) and if enough water has been expelled, it will fall below 0.5 bar and the boiler locks out until more water is added to the heating circuit via the fill loop.

Thus a frequent loss of pressure in the heating circuit does not always (not even usually) imply a leak. It is more likely due to a failed expansion vessel.

[tggzzz]

Here in the UK we mostly use 'combi' boilers. The cold mains water flows through a heat exchanger in the boiler on its way to the taps. Thus, the hot water to the taps is at mains pressure.

The heating system is a closed loop and the water is directly heated in the boiler and pumped around the radiators. The boiler has a 'filling loop' which - when two valves are opened - connects the mains water to the closed heating circuit to add more water to it. The heating circuit has an expansion tank comprising a sealed vessel with a membrane down the middle. The heating circuit water is on one side of the membrane and air (or nitrogen) on the other. Water is added to the heating circuit via the filling loop until the pressure in the heating circuit reaches 1 to 1.5 bar, cold (typically).

If the heating circuit has a leak the pressure gradually falls, as revealed by the pressure gauge on the boiler. If it falls below 0.5 bar (typically) the boiler will cut out.

If the pressure in the heating circuit rises above 3 bar (typically) a pressure release valve opens and water is dumped into the condensate outlet pipe.

The expansion vessel has a limited life. When the diaphragm fails, the air is expelled and the vessel fills with water. Thus it is no longer able to "buffer" the pressure rise when the water in the heating circuit is heated. As a result the pressure rises quickly and - when it reaches 3 bar - begins to be expelled through the pressure release valve. When the heating system switches off, the pressure falls quickly (due to the lack of buffering) and if enough water has been expelled, it will fall below 0.5 bar and the boiler locks out until more water is added to the heating circuit via the fill loop.

Thus a frequent loss of pressure in the heating circuit does not always (not even usually) imply a leak. It is more likely due to a failed expansion vessel.

I've seen all that in my parent's heating system.

What I don't understand and the heating engineers technicians have never been able to explain is what the pressure meter is actually measuring.

My parent's house was 4 stories (i.e. ~70ft) tall with the boiler in the basement. 1 bar is 32ft of water, so the height of the top-floor radiators should result in a pressure of at least 2 bars in the boiler radiator circuit. So what does a reading of 0.6bar (I've seen lower!) actually mean?

It can't be the pressure relative to the mains pressure, since that was (1) much more than 2 bars and (2) was isolated (as you describe) by the manual valve inside the boiler.

[Berni]

The water in the central heating loops can get vacuum locked when you drain it.

This sort of situation can make for a surprise when servicing the system, where you drain it and start taking it apart and seams like no water is flowing anymore. But then as you disturb it you get air bubbles traveling trough pipes and breaking the vacuum holding the water up, suddenly you have all the water in the radiators dumping down and out of the pipe you are taking apart, making a big mess. So it is a good idea to either shut both top and bottom valves on all the radiators so that it can't drain, or properly drain them by opening the little priming valves on the radiators to let air in.

Here the pressure gauges on central heating show pressure relative to ambient (they show 0 bar when not connected) makes sense since that basically shows the height of the water column above the gauge + any extra pressure.

Tho over pressure protection valves here are often not really routed to any drain, they just barf out onto the floor. Probably because that valve opening indicates something is wrong, so spilling on the floor gets the attention of the user that much more. Haven't really seen them open up, just sometimes leak slightly due to old age. (apart from firing up a wood furnace way too much and getting the water >120°C)

[tggzzz]

Here the pressure gauges on central heating show pressure relative to ambient (they show 0 bar when not connected) makes sense since that basically shows the height of the water column above the gauge + any extra pressure.

That i can understand!

It is the 0 bar when there is a 15-20m head of water that baffles me.

[m k]

Initial pressure?

Bottom of expansion vessel to high point of circulation network in 10 meters is one limit.

[BILLPOD]

Well, even if OP Eassssse, never comes back, I'm sure all of us picked up some plumbing knowledge;  I know I did.   Thanks to all who shared their knowledge and expertise.   

[tggzzz]

Initial pressure?

I doubt it would "remember" the pressure 10 years ago!

Bottom of expansion vessel to high point of circulation network in 10 meters is one limit.

Zero bar in boiler relative to what? Nothing in manual. Haven't found explanation on web. At least two installation technicians have never thought about it, and when I "encouraged" them to think about it they couldn't answer.

[Berni]

Here the pressure gauges on central heating show pressure relative to ambient (they show 0 bar when not connected) makes sense since that basically shows the height of the water column above the gauge + any extra pressure.

That i can understand!

It is the 0 bar when there is a 15-20m head of water that baffles me.

You can have pockets of vacuum in the system that are holding the water up. This is what causes the problem of draining the system by just opening the tap at the lowest point, some of the water will come out, but some gets held up above you by areas of vacuum because air doesn't have a way to get in. (But if you disturb that vacuum while working on the system you are gonna get wet as it suddenly dumps out)

There can be multiple of these pockets in the system. Even if the total height of your pipework is 30m you could split it up into 3 sections of 10m that are held up by vacuum (especially since the pipework might be very twisty). Some of the separations possibly created by air that leaked in. Once this happens the whole system doesn't act like one big water column anymore. So the pressure gauge might only be seeing the water column in one section of pipework.

Initial pressure?

I doubt it would "remember" the pressure 10 years ago!

Some of the pressure gauges we use for central heating have a feature of the front glass being able to rotate, that glass has an extra needle painted on it. The point is to set this needle at a pressure you wish to run at, then always top up the water in the system until the actual pressure matches that set pressure. When you look at it years later you can see exactly now far below the needle dropped. Some other central heating pressure gauges just have a extra red line painted at around 2.5 bar for you to fill the water to.

Tho fair to say that these pressure gauges are pretty prone to sticking because they sit at the same pressure for very long periods. So if the pressure doesn't make sense, or doesn't go up as you fill it, it is worth giving the gauge a few procusive maintenance whacks to help unstick it.

[m k]

Initial pressure?

I doubt it would "remember" the pressure 10 years ago!

Bottom of expansion vessel to high point of circulation network in 10 meters is one limit.

Zero bar in boiler relative to what?

Not boiler, the pump, cavitation prevention.
So relative to internal pressure of sealed expansion vessel.

[tggzzz]

Here the pressure gauges on central heating show pressure relative to ambient (they show 0 bar when not connected) makes sense since that basically shows the height of the water column above the gauge + any extra pressure.

That i can understand!

It is the 0 bar when there is a 15-20m head of water that baffles me.

You can have pockets of vacuum in the system that are holding the water up. This is what causes the problem of draining the system by just opening the tap at the lowest point, some of the water will come out, but some gets held up above you by areas of vacuum because air doesn't have a way to get in. (But if you disturb that vacuum while working on the system you are gonna get wet as it suddenly dumps out)

There can be multiple of these pockets in the system. Even if the total height of your pipework is 30m you could split it up into 3 sections of 10m that are held up by vacuum (especially since the pipework might be very twisty). Some of the separations possibly created by air that leaked in. Once this happens the whole system doesn't act like one big water column anymore. So the pressure gauge might only be seeing the water column in one section of pipework.

Seems unlikely in my case.

I bled the air out of the top floor radiators and the let water in until pressure had risen to 1.5bar. Then repeat a couple of times until no more gas was released. Thereafter radiators became hot, as expected.

Initial pressure?

I doubt it would "remember" the pressure 10 years ago!

Some of the pressure gauges we use for central heating have a feature of the front glass being able to rotate, that glass has an extra needle painted on it. The point is to set this needle at a pressure you wish to run at, then always top up the water in the system until the actual pressure matches that set pressure. When you look at it years later you can see exactly now far below the needle dropped. Some other central heating pressure gauges just have a extra red line painted at around 2.5 bar for you to fill the water to.

Tho fair to say that these pressure gauges are pretty prone to sticking because they sit at the same pressure for very long periods. So if the pressure doesn't make sense, or doesn't go up as you fill it, it is worth giving the gauge a few procusive maintenance whacks to help unstick it.

Definitely a.simple gauge, needing grappling like an android barometer. Red plastic fiducial mark was moved by screwdriver blade, and then stayed where it was left.

[Sorama]

probably a needle to set the maximum pressure...
this is just an indicative needle...doesn't measure anything at all.

[Terry Bites]

That looks like a really good and very cheap solution.

[SteveThackery]

What I don't understand and the heating engineers technicians have never been able to explain is what the pressure meter is actually measuring.

My parent's house was 4 stories (i.e. ~70ft) tall with the boiler in the basement. 1 bar is 32ft of water, so the height of the top-floor radiators should result in a pressure of at least 2 bars in the boiler radiator circuit. So what does a reading of 0.6bar (I've seen lower!) actually mean?

It can't be the pressure relative to the mains pressure, since that was (1) much more than 2 bars and (2) was isolated (as you describe) by the manual valve inside the boiler.

Excellent question, and I hadn't thought about it before. It is the pressure relative to the ambient air pressure. I don't think the rules about feet or metres of 'head' apply to a sealed system, do they? I visualise a simple vertical pipe, closed at the top and bottom, filled completely with water. Assuming there is a tap at the bottom, opening it will release no water (ie zero pressure) unless the tap also lets air in.

Interesting question and it needs thinking about!

[Analog Kid]

It would be great, if OP replied.

Maybe they didn't really expect any replies to a plumbing question on an electronics forum ...

[tggzzz]

Closed in normal operation, but not while venting gas (until water appeared) on the top floor. Never needed to release water at the bottom.

I would

• vent as much gas as possible at the top
• close vent
• allow water in at the bottom until pressure had increased to ~1bar
• revent at top
• rinse and repeat until water appeared at vent
• finally increase the pressure to ~1bar

Between 2 and 3 the pressure gauge indicated ~0bar, even though there was a column of water above it. above it.

IIRC the expansion tank/bladder had to be reinflated regularly. I imagine a larger bladder would have been beneficial; don't know why there wasn't one.

[coppercone2]

'if you have access to a suspicious pipe you cannot shutoff then you can freeze it temporarily.

If the noise stops after you freeze it it means its related