Isolating Radiators Part 2 - Mystery Pressure Drop

[Ermintrude]

Thermal test and moisture test won't show squat. Concrete is a heat guzzler and unless the camera has an amazingly high resolution and uber fast refresh rate?

 

[DavidGee]

The survey was done by a professional company using a FLIR T440BX camera.

I have to say the images are pretty sharp and I would have thought shown up a water leak.

A number of people suggested this approach on this site and it seemed a sensible thing to try.

Just wish I could get to the bottom of this one ...

D

 

[Ermintrude]

If pipes cold ain't showing squat. Those cameras are ok for wood floors and massive red hot leaks and rads that are full of sludge. Thermal cameras ok but if 200mm concrete u will struggle with anything less than the Hubble ! Pressurise the gauge won't lie. Test with water and not air! As air will expand on compression and contract when system settles down leading to false measurements.

 

[Billy Bob Bob]

Firstly, thank you to everyone who commented on the last post with regard to this issue ... the post were appreciated.

Just to recap I have a pressurized central heating system which is losing pressure ... an engineer having checked the system informed me that I have a leak under the floor (the pipes are buried in concrete) the previous post basically asked if if I could help locate the leak by isolating the radiators .... clearly I can't.

Since the last post the following has happened.

Valves have been fitted on the pipework to separate the upstairs and downstairs heating. When the upstairs heating only is on everything works perfectly, when these valves are opened to allow to whole system to operate (upstairs and downstairs) the pressure drops quite rapidly thus giving the impression that the leak is downstairs.

Given this a thermal survey was undertaken of all the downstairs heating pipework, no leak was found and as most of the pipework ran against the walls moisture readings were taken along these piperuns and no evidence of moisture was found in the walls.

This survey was repeated again upstairs with the same results ... no leaks were found were found or moisture detected.

Does anyone have any suggestions as to what could be causing this situation?

The amount of water being lost is quite significant the pressure fell from 1.5 bar to 1 bar quite quickly and I had to top up the system three time in the afternoon whist the survey was being undertaken. There is no evidence of water escaping from the external expansion pipe and the boiler when only heating upstairs seems to be working fine with no loss of pressure.

If anyone has any thoughts on this one it would be appreciated.

As an aside due to the size and open plan nature of the house the piping can't be dropped in from above to avoid the downstairs piping (which does not appear to have leak in any case)

Thank you

D

quite a easy,mechanical,non BS answer my friend leaks down stairs thermal imaging is pants

 

[armyash]

Dodgy expansion vessel?

 

[Mike Jackson]

Dodgy expansion vessel?

No. The leak is definitely in the downstairs pipework. people are making this over complicated. If the system is fine when the valves to downstairs are shut but leaks when they are open it's going to be a leak on the downstairs circuit. As has been suggested above, disconnected this section and separately pressure testing will confirm.

 

[Geyser]

I had a similar problem once. Turned out a rad had been disconnected and valves built in under floor. Every time I went pressure test would be fine but overnight temp would drop and trv open. So happy when I found it!! Check outside for leaking drain off valve, apart from that you've had good advice. Wet test and find that pesky leaky joint..

 

[SimonG]

No. The leak is definitely in the downstairs pipework. people are making this over complicated. If the system is fine when the valves to downstairs are shut but leaks when they are open it's going to be a leak on the downstairs circuit. As has been suggested above, disconnected this section and separately pressure testing will confirm.

Sometimes it is the obvious.

 

[happyflyer]

LPC,

You must be dead dedicated or the Poirot of the plumbing world

 

[RoryD]

I would have thought that if all is well when downstairs is isolated but not if it is open..it has to be a leak there regardless of the test. PRV or leaking through the condensate would happen whether just upstairs on or the whole system on. Good Luck