System losing pressure

[dilalio]

There is a leak.
Cheapest for you to find it.
If you can't then you need to employ someone who can.
There is at least one company who offer a no fee if leak not found policy.
They have all kinds of expensive, specialist kit which they employ without the need to go demolishing walls, floors etc.
You can try the leak sealer but it's not an engineering solution - more of a bodge job!

 

[Katie Hellewell]

Thank both. It is a system boiler (Worcester Greenstar, unfortunately I don't know the model but I can check when I get home). We have an unvented hot water tank upstairs.

I'll check for a pressure gauge on the boiler later, but I've never noticed one.

We'll also go around the house again and check for leaks, but I am sure that there isn't a visible/accessible leak. It is just so frustrating!

 

[Katie Hellewell]

The boiler is a Worcester Greenstar Camray utility 18/25 – oil fired.


The issue is that we are dropping pressure to zero within a few hours of topping up the system. The pressure drops whether the heating/hot water are in use or not.


Worcester came out – the engineer isolated the boiler from the pipework. The pressure gauge is on the expansion vessel and the pressure dropped when the boiler was isolated, so he confirmed that the issue is in the pipework rather than the boiler.


I understand that if the expansion vessel was faulty, it would be discharging water out of the pressure release valve. We tied a bag around the PRV (outside) a week ago and it hasn’t collected any water, so we are assuming that the expansion vessel is ok.


I have read that the heat exchanger may be faulty which would discharge out of the condensate, but as the Worcester engineer confirmed that the issue is in the pipework and not the boiler, I don’t think that this is possible?


Finally, we have an unvented water cylinder upstairs. This isn’t leaking or showing any signs of damage, however is it possible that there is an issue with this that is causing the system pressure to drop?


Other than that, we are concluding that we have quite a significant leak somewhere, however we can’t find it so it’ll have to be one of the leak detection companies to locate and fix it.


The Worcester engineer has told us not to use the boiler until we have resolved the problem, as the constant topping up of the system with fresh water will cause the heat exchanger to fail. Is there an inhibitor that we can put into the system to solve this please? I expect that the water in the system is now just water with no inhibitor left.

 

[Hugh Jaleak]

If the boiler was isolated from the pipework, and the pressure dropped, then yes, the issue is in the pipework. To be honest, all the pointers are to a leak, rather than a failure of the Heat Exchanger, Expansion Vessel or Pressure Relief Valve. I don't know the details of your system, but with unvented, if the coil had pinholed I suspect it would be over pressurising the heating system, (giving the opposite issue!), rather than the heating leaking into the hot water.

I would be looking at the concrete floor as one of the first areas for investigation. Concrete corrodes copper, if the pipe wasn't suitably and/or adequately protected when it was laid, before the concrete was put over it, this can quickly lead to the pipework failing.

You can put any suitable inhibitor in, but as the engineer has said, constant topping up will merely dilute it once again, you really need to get the leak isolated and repaired, then top up the inhibitor again. Worcester are obviously aware now of this issue, and no doubt will be taking it into consideration in the event of any warranty claims on your boiler.

 

[Katie Hellewell]

Thank you for your help. That is really helpful.

We added two bottles of inhibitor yesterday. As a last resort before we call the leak detectors in, we also added a bottle of leak sealer yesterday. Apparently this takes 24 hours to work, so hopefully we'll have some good news when we get home tonight.