Tracing a Central heating leak - under hardwood floor!!!!
Discussion
So, got a central heating system that is losing 1 bar of pressure over the course of 4 days - having to top it up more and more frequently - and it seems to be taking more each time!
Its clearly not leaking from upstairs as we haven't had any leaks or signs of water/staining etc.
So I think its leaking downstairs somewhere ....only trouble is...we laid very expensive hardwood flooring downstairs when we did the house out - (its a slightly suspended floor......hardwood over 2" beams)
So clearly I don't want to have to pull the floor up , room by room, to try and find the leak.
Does anyone have any bright ideas, or preferably experience , on how to discover the approximate location of the leak??????
Thanks!
1point7bar said:
Rickyy said:
Are you sure it is a leak and not an expansion fault and losing pressure through the pressure relief valve?
Good point, What pressure are you trying to hold?ATTAK Z said:
I'm sorry to say this (honestly) but it sounds like you're fooked ... how long has the heating been in ? ... is it in the ground floor sreed ? ... if so is it copper pipe ? ... if so is it protected with Denso tape or similar ?
Heating been in about 14 years - its flexible pipe under the floors - copper above the floors. Its not a screed - its suspended timber - some rooms have about 12" space under timbers......some have timbers laid on a concrete sub-base.1point7bar said:
Maybe drain the system and then connect a compressor to the supply instead of mains water. Slowly dial up the pressure until you can hear the air leaking. A condenser boiler should hold 30psi easily.
Hmmmmm...good idea.....its an oil fired boiler though...(we live rurally)......only concern is that too much pressure might end up blowing some of the flexible pipe unions/joints???
dealmaker said:
Hmmm.....where would the water be going if it was juts an expansion fault?????? I have two expansion vessels in the loft - and I am trying to keep the system at around 1.5 to 1.7 bar. The pressure drops to circa 0.6 bar after 5 days or so - then I need to open the top up valve (basically dumping mains pressure water into the system )- and that gets it back up to 1.7 bar again. Water must be going somewhere???????
You'll have a pressure relief valve somewhere on the system with pipework leading to outside, water will be discharging from there if there is a fault.PRV looks like this....
The expansion vessels will have valves on them like a car tyre, press the valve and if water comes out, you've found your problem.
Just had this losing a 1barish every couple of days, after 'eventually' getting the plumber out 
, one of the Rads had been knocked and water was seeping down the pipe, took a couple of days to show through the ceiling'
Check the pipes either end of the rads to see if they need tightening,, I luckily got off with a cheap bill
, one of the Rads had been knocked and water was seeping down the pipe, took a couple of days to show through the ceiling'Check the pipes either end of the rads to see if they need tightening,, I luckily got off with a cheap bill
Rickyy said:
dealmaker said:
Hmmm.....where would the water be going if it was juts an expansion fault?????? I have two expansion vessels in the loft - and I am trying to keep the system at around 1.5 to 1.7 bar. The pressure drops to circa 0.6 bar after 5 days or so - then I need to open the top up valve (basically dumping mains pressure water into the system )- and that gets it back up to 1.7 bar again. Water must be going somewhere???????
You'll have a pressure relief valve somewhere on the system with pipework leading to outside, water will be discharging from there if there is a fault.PRV looks like this....
The expansion vessels will have valves on them like a car tyre, press the valve and if water comes out, you've found your problem.
Also our taller towel-warmer style radiators are sling heat in their upper halves as the pressure drops - which to my simple mind suggested there was a leak somewhere and system was draining down involuntarily?? Would it still do this if we were losing water via the expansion tanks in the loft - above their position?
As Rick tightly says, check that it's a leaky pipe, might be over expanding.
Look at the expansion vessel, each one should have a schrader valve. Dab the pin on these to see if air or water comes out.
If the latter, bad times.
As the water heats up, it expands, a ruptured diaphragm in the vessel won't take up the expansion and thus kick it out the pressure relief valve.
If it is a leak, you can use a radweld type substance approach. It's called leak seal. It'd be worth a try before ripping up a floor. Put the right dosage in and see if the frequency of topping up the system lessens.
Look at the expansion vessel, each one should have a schrader valve. Dab the pin on these to see if air or water comes out.
If the latter, bad times.
As the water heats up, it expands, a ruptured diaphragm in the vessel won't take up the expansion and thus kick it out the pressure relief valve.
If it is a leak, you can use a radweld type substance approach. It's called leak seal. It'd be worth a try before ripping up a floor. Put the right dosage in and see if the frequency of topping up the system lessens.
dealmaker said:
I'm not sure if there is anything leading outside from the expansion tanks in the loft???? Surely the water would be going somewhere outside via a pipe if it was seeping out via the expansion tanks?
Also our taller towel-warmer style radiators are sling heat in their upper halves as the pressure drops - which to my simple mind suggested there was a leak somewhere and system was draining down involuntarily?? Would it still do this if we were losing water via the expansion tanks in the loft - above their position?
If the system is installed correctly, you will have a valve like I posted which should have copper pipework leading to outside, usually turned back to the wall. But if your expansion vessels are in the loft, they may have terminated the pipework into a gutter making it hard to spot.Also our taller towel-warmer style radiators are sling heat in their upper halves as the pressure drops - which to my simple mind suggested there was a leak somewhere and system was draining down involuntarily?? Would it still do this if we were losing water via the expansion tanks in the loft - above their position?
I had exactly this happen to me with an unvented system. It started with loosing 1Bar every three months or so until (three years later) it would lose all it's pressure in the space of an hour.
So, as I understand it the basic reasons can be....
1. Losing pressure from a PRV. Attach a balloon over the outlet of your PRV and you will soon find out whether there is a poproblem as the balloon will fill up with water.
2. Possibility that that you could have a problem with an expansion vessel but even then, the pressure and/or water needs to be leaking somewhere. Press the valve on the top and if water comes out, hey presto!
3. Maybe a problem with and auto-bleed valve but again, the water should be going somewhere.
4. A crack inside the water cylinder itself. Can be tested if you shut off the mains feed to the cylinder and turn on a hot tap which should run dry eventually (I think).
5. A leak.
I had a leak which took three years to actually show itself by travelling under a tiled bathroom floor and hitting a wall and rising up it. Basiocally, the water was draining away somewhere and it never showed itslef. It only showed up when the volume of water leaking got very large.
I had to rip out an entire bathroom and adjoining dressing room to find that the plumber who installed it (three years previously) had forgotten to solder one side of a joint properly. This was also the day before Christmas eve, no heating and the mother-in-law coming to stay!
Whatever you do, check with your insurer that you have 'trace and access' cover. If you do, that will cover you to find the leak, access it and mend it. I had an almighty row with my insurance company about this, long story but basically I won but only after I had compleetd the repair myself.
There are companies that will trace your leak using thermal imaging cameras and also a gas detection technique. I has a quote for about £800 I think to find the leak but I didn't need it in the end.
I have also found that not many insurance companies offer trace and access cover any more, it took me a while to find one. I wouldn't be without it now as it would have cost me several thousands.
Good luck.
So, as I understand it the basic reasons can be....
1. Losing pressure from a PRV. Attach a balloon over the outlet of your PRV and you will soon find out whether there is a poproblem as the balloon will fill up with water.
2. Possibility that that you could have a problem with an expansion vessel but even then, the pressure and/or water needs to be leaking somewhere. Press the valve on the top and if water comes out, hey presto!
3. Maybe a problem with and auto-bleed valve but again, the water should be going somewhere.
4. A crack inside the water cylinder itself. Can be tested if you shut off the mains feed to the cylinder and turn on a hot tap which should run dry eventually (I think).
5. A leak.
I had a leak which took three years to actually show itself by travelling under a tiled bathroom floor and hitting a wall and rising up it. Basiocally, the water was draining away somewhere and it never showed itslef. It only showed up when the volume of water leaking got very large.
I had to rip out an entire bathroom and adjoining dressing room to find that the plumber who installed it (three years previously) had forgotten to solder one side of a joint properly. This was also the day before Christmas eve, no heating and the mother-in-law coming to stay!
Whatever you do, check with your insurer that you have 'trace and access' cover. If you do, that will cover you to find the leak, access it and mend it. I had an almighty row with my insurance company about this, long story but basically I won but only after I had compleetd the repair myself.
There are companies that will trace your leak using thermal imaging cameras and also a gas detection technique. I has a quote for about £800 I think to find the leak but I didn't need it in the end.
I have also found that not many insurance companies offer trace and access cover any more, it took me a while to find one. I wouldn't be without it now as it would have cost me several thousands.
Good luck.
Edited by Jonnas on Saturday 4th February 22:20
Good luck. We have been having issues for past 2 months. Not helped by a pool heater with a specialist bit of kit that has also been suspected as faulty and pipes running externally through lagged boxing.
So far the pumps have had to be replaced (ran dry while we were away!), the pressure vessel (ruptured diagphram) and the pressur reliefe valve.
Water pressure is still dropping over a few days. Some days its worse than others.
We rent so landlords problem, but I'm tearing my hair out, trying to sort it. Plumbers equally frustrated.
Leak filler worth a shot, but you would imagine that it's delaying the sympton rather than fixing it.
So far the pumps have had to be replaced (ran dry while we were away!), the pressure vessel (ruptured diagphram) and the pressur reliefe valve.
Water pressure is still dropping over a few days. Some days its worse than others.
We rent so landlords problem, but I'm tearing my hair out, trying to sort it. Plumbers equally frustrated.
Leak filler worth a shot, but you would imagine that it's delaying the sympton rather than fixing it.
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