Do I have a leak or not??

[nervous123]

A few months ago we had a new sealed unvented system fitted. (Boiler: Vaillant Ecotec 630. Cylinder: Telford Tempest. Expansion vessel: Zilmet 110. Pipework replaced 'where builder thought necessary'. 5 new rads fitted and 7 old ones kept)

If relevant, let me add that the cylinder was certainly not installed by a GS-reg engineer, and that even tho I got a GS-certificate for the boiler, another engineer found some aspects of the boiler installation contravened B'Regs. (but all that is covered in some detail in another of my posts here http://www.ukplumbersforums.co.uk/c...251-hw-only-works-when-ch-other-problems.html)

Anyway, boiler pressure seemed to drop on a regular basis and I'd have to refill it every few weeks. Pressure would drop to as low as 0.8 (sometimes even 0.6 if both HW and CH been off for a while) when cold, then rise when boiler fired up, then drop again when thermostat turned boiler off.

• There are no visible leaks from any of the rads.
• I put a balloon on the PRV for 2 days and no moisture came out.
• I have read on forums about repressurising the expansion vessel, but could not see any valve on mine that would enable me to do so.
• I recently bled all the rads (not for the first time) and only one (upstairs bathroom) had air in. (interestingly, when I have bled the rads in the past, it's always been this one that has had air)

Last night I did a 'test run' to try and ascertain if there is definitely a leak or not. I turned off both CH and HW at 8.00pm. Cold pressure was then 1.3. Overnight, pressure dropped to 1.0 - but has remained at 1.0 throughout today, over 20 hours later. (I have since turned it back on, pressure rising quickly to 1.8)

This prompts 3 queries:

1. Surely if there is a bona fide leak, pressure would not have stabilised at 1.0 but would have continued dropping?
2. How can it be that pressure seems to drop faster/lower when the system is on, than when it is off? Is it possible I haven't got a leak after all but something wrong with one of the physical components of the system? Someone suggested the coil in the cylinder may be gone already...?
3. If I do have a leak, is it more likely that it is in the near vicinity of the bathroom rad, as that is the one that often fills with air? (Then again, it is one of the first in the house to get hot, so I think it may be near the 'start' of the system)

Many thanks. Sorry for the length of this post, but I want to include as much info as possible, before I call a Leak Detection firm to come for £300/400...!

 

[Bartdude]

If you have a small leak on the system it could be that it's only leaking when the pressure is over 1bar. When you have the heating on the pressure rises due to expansion,which is why it would drop faster. Also the heat could be causing the leak to open up a bit more.

I would put a pressure test on the system pipework with proper testing gear. If that confirms a leak then you have to start looking for it. You might get lucky and find it quickly,or it might mean floors coming up. Good luck.

Edit: I've just looked at your previous thread and judging by the quality of the work it could well be a leak on the system!

 

[tamz]

If you have a leak it is a very small one if it takes a few weeks to drop.
Check around all rad valves or compression fittings. Look for green or brown marks on the pipes. You may not notice anything wet as it will dry up with the heat.
If you are having to bleed the bathroom radiator, as you have a sealed system this means there is corrosion happening inside the system. Get some inhibitor put in to stop it.
Btw if you are bleeding rads this drops the pressure. There is also an auto air vent inside the boiler that will release any air (more likely hydrogen) trapped in the system as it passes through the boiler which will also drop the pressure.
The system pressure also rises when it heats. This is normal.

 

[nervous123]

Get some inhibitor put in to stop it.

thanks.
however, the GS-reg engineer i had in to rectify the problems with the original installation, was reluctant to add inhibitor if there was a leak as it would just leak out somewhere and not be much use... he wants to wait until the leak is sorted out

 

[tamz]

For the sake of just over a tenner stick some in it.

 

[Gray0689]

Stick a jar of leak sealer to

 

[stani]

try some fernox leak sealer, if its only a small leak. it can take up to a week to work completely but if it is so small this should stop you having to call out a leak detection firm. I dont normally like this type of thing but had to use it a few weeks ago on a 'new boiler on old system' and it worked a treat. dont forget it can take up to a week to work and make sure you put in enough for your system capacity.

 

[Centralheatking]

Leaks/pressure drop on a sealed system are their achiles heal. For a system with 7 or so rads a pressure drop of 1 bar ish (from 1.5- .5) might only mean in real terms less than a pint of water.

Couple this small amount over a week or so and you will find it difficult to find because it might even be evapourating from where it is and leaving little evidence. I would start at the boiler connections and move on to the radiators - valves and tails. Then all visible and easily exposed pipes and joints.

A pressure test will not in all likely hood locate the weep. I would keep repressurising and hope the tiny leak will crud up in time or put some leak sealer addative in (fernox I have used).

There is a device to compensate for small pressure drops on sealed systems but it does not fix the leak.

centralheatking

 

[stani]

just looked at your other thread, and like most of the other installers have never seen anything 'supposedly new' as bad. suggest you contact 'Cowboy builders ' on the tv. name and shame.

 

[Gray0689]

just looked at your other thread, and like most of the other installers have never seen anything 'supposedly new' as bad. suggest you contact 'Cowboy builders ' on the tv. name and shame.

I agree dont think you will ever have any faith in your heating and water system

 

[tamz]

Hope the cylinder doesn't need drained.

 

[stani]

just found out that this thread is going to cost me in the region of £150, while ranting and raving about the state of the installation I looked through my certs, and found out my G3 ran out in november, am now urgently looking for a re-assessment,