How do you track down a leak in underfloor radiator piping?

[MrInteractive]

I was hoping someone might be able to assist me with some hints and tips on tracking down a leak in the pipe work of my ground floor central heating.

My ground floor is the following with the leak highlighted as "water"

I would like to know if there is some sort of procedure to help me track down the source of the leak. The leak doesn't seem to be near the area around the water or the pipe next to it. I am reluctant to dig up the scree around the pipe further without some procedure to find the leak.

When I turn the heating on the water disappears and when I turn it off it reappears. The pipe is hot and so is the water when the heating is turned on. The pipe gets hot after the other radiators get warm and seems to be part of the return to the boiler. I believe other pipework exists as indicated.

The exposed pipe seems to be set in sand under the 1cm thick concrete scree which forms the floor.

I am a little confused by the turn of the exposed pipe to the right when the temperature sensations on the floor indicate the pipe would be likely to go to the radiator at the top of the diagram.

Do I need some sort of water dye to put into the water to help me see where the water is coming from?

Do I need some sort of air pressure device to flush out water from pipework when I do the find leak and attempt to fix it by brazing new pipework or whatever ?

Any help appreciated.

 

[RigidRaider]

If you've got radiators this can't be underfloor heating. It sounds as if a pipe has ruptured, time to check your house insurance and get digging. Before you expose the leak make sure everything's cold and you know where the drain point for the CH is hidden. Have lots of towels and buckets handy to catch the geyser.

Or call out one of the gentleman plumbers in your Yellow Pages.

 

[MrInteractive]

You are right of course, I shouldn't have called it underfloor heating, just underfloor piping for my radiator central heating.

I have exposed the area around the water by removing the scree, but as I say the leak seems to be somewhere else.

I saw in another thread there is some smelly perfume or something one can stick in the boiler water feed.

I have drained the boiler on previous occasions so I do know how to drain it, although for some reason I have been unable to drain the lower system, presumably because of the leak?

 

[BingoBongo]

check the rad

then check it again

ive seen a leak on a trv run down the insulation on microbore

 

[MrInteractive]

I don't know what microbore is but the copper piping exposed by digging up the scree near the water appears to be 15mm. I do consistently get a very loud "twang" noise emitted from the radiator at the top of the diagram some 30-60 minutes after the heating is turned off.

There is no water near the radiator on the floor, when you say check the rad, do you mean check the piping under the floor near the rad or the piping connecting to the rad?

 

[mickyg]

When I turn the heating on the water disappears and when I turn it off it reappears.

what kind of heating system is it? sealed or vented? can you work out how much water your losing? if its alot then a stethoscope might help. Also thermal imagining. However the traditional method is to work out the vicinity of the leak and dig!

 

[MrInteractive]

It is a vented system.

I have started digging, I dug up about a square foot of screed and discovered the pool of water and the pipe. I was reluctant to dig further as the leak wasn't apparent from the exposed pipe and I didn't have a procedure. I could see water flowing into the pool of water from the surrounding sand but couldn't be sure where it was coming from, it seemed to be coming up from the sand under the screed.

 

[MrInteractive]

Is there a dye or something I can put in the CH water so I can see where the flow is coming from? And presumably one would need several coloured dyes as one made multiple tests and investigations.

 

[glasgowgas]

putting in dye is only reqd once to determine if the water in the
floor is from ch system or not.

when you have determined its ch water where you start to dig is down to you

 

[fatplumber]

Dig down where it is wetest first when you have exposed the pipe, you will be able to see which direction it is coming from. Then just dig towards the leak, carefully. This is an insured risk. They will not pay for repairing the leak but they will pay for the damage done while lokking for the leak.

 

[wolfman1]

from a likely hood perspective, joins and bends are more likely to leak. and especialy where the pipe turns up to the rad, looking at your diagram, is the water coming from boiler direction? I would check the boiler connections in casei t is running down.

 

[leakydave]

Never needed to use one but a thermal imaging camera could be helpful

 

[MrInteractive]

from a likely hood perspective, joins and bends are more likely to leak. and especialy where the pipe turns up to the rad, looking at your diagram, is the water coming from boiler direction? I would check the boiler connections in casei t is running down.

Thanks for that.

The water SEEMS to be coming from the top of the diagram, i.e. towards the radiator at the top of diagram.

I have checked the boiler connnections and they seem fine and the inside of the boiler area is also dry.

The radiator at the top of the diagram does make some very violent "twang" noise about 30 minutes after the heating is switched off which does make me suspicious about it.


I am going to attempt to track down the leak tomorrow and get digging.

Am I going to need some sort of air compressor thing to remove the water from the system once I have tracked down the leak if it is in the underfloor area? I understand from my local plumber such a thing exists.

Ever since I drained the system some years ago I don't seem able to drain out the water from the ground floor piping, and anyway presumably one cannot completely drain the pipes which are at the lowest point, particularly if there is a leak.

If the leak is at a joint near the radiator then presumably it will still be difficult to remove the water so that I could so some sort of soldering/brazing.

 

[MrInteractive]

Dig down where it is wetest first when you have exposed the pipe, you will be able to see which direction it is coming from. Then just dig towards the leak, carefully. This is an insured risk. They will not pay for repairing the leak but they will pay for the damage done while lokking for the leak.

That is very useful information, thank you very much indeed for info on procedure and the insurance issue.

 

[MrInteractive]

Just to bring this story to a conclusion.

Because the pool of water was next to a non-leaking non-jointed pipe I was very concerned that the leak was elsewhere and flowing to the point where I found the pool of water.

On observing the pool of water recede and then reappear as I switched the heating on and off I noticed that quite often bubbles or little flows of water or sand would occur ( this area was filled with sand and not concrete ) at the bottom of the pool.

Eventually I got my courage together and started digging further and found a pipe and a compression joint just underneath the pool of water and the compression joint of a T piece was leaking. While trying to chisel out the sand and screed I found myself chiselling a very solid object which later turned out to be the gas pipe to the boiler, fortunately I gave up bashing it after a short while because I was suspicious it might be important.

So anyway, I found the problem and the pipework in the area was appalling and full of other compression joints, and eventually I called in a plumber who fitted a new soldered T piece to replace the compression T piece and it all ended happily ever after and my insurance company fixed all the horrendous damage to carpets, walls, plaster, skirting boards, door frames etc etc.