Saunier Duval Themaclassic F24E Losing Pressure

[alarmguy123]

Hi guys

I am really hoping someone can help me here.

Quite a lot has happened to get to this point, so please bear with me.

This boiler was already installed when I bought my house and it has served me well in the 7 years I have been here (it was installed 14 years ago) - I have had it serviced every year as I believe if you look after things, they will look after you.

I was away for 5/6 days and when I got back, the boiler wasn't right (it worked perfectly before this, but the central heating hadn't been switched on for months). It was acting very strange when using hot water, struggling to get going, it would work for a bit and then and both bars on the display would flick all the way to the top and then it would cut out and the red light would flash on it. It was just acting weird. It was due for it's yearly boiler service anyway, so my boiler engineer came over and said it was down to a faulty circuit board. I picked one up and he fitted it and the boiler came back to life again and seemed great, no more gremlins! He finished servicing the boiler (had to re-pressurise the expansion vessel during the service) and I thought everything was great.

However, when I went to put the heating on, the boiler would lose pressure after about 30-60 mins and it would cut out and the red light would flash. A quick top up via the (leaking) filling loop and it would work again. With the heating, the pressure will sometimes go up to 2 bar (from 1) and it heats up nicely, then the pressure will drop until the boiler stops working and the red light comes on.

Something to note here is that my filling loop has always been rubbish and leaks water when you use it (have to put a bowl under it) - but usually it has always done it's job and filled the boiler when it has been needed every now and again. The engineer has been saying for years he will get the part to fix it to stop it leaking when used, but he has never got round to fixing it. When he looked at it when all this was going on, he said it was shooting water in a few different directions when he tried to top up the pressure after fitting the new PCB and said it would not fill past about 1 bar with it fully open. I have a feeling this could be why the original circuit board needed replacing - because water got into it over time?

Either way, he left me with a supposedly working boiler. But it just keeps losing pressure. I have checked the pressure relieve valve pipe and there is loads of water on the driveway that has come out of it.

He told me that the expansion vessel will probably need replacing without really looking into any other options but after some research it sounds like the pressure relief valve commonly goes on these boilers and it could be that that needs replacing?

I am learning as I go with this as have done loads of research but any help would be great.

So it has a leaking filling loop which doesn't seem to be letting much water in - when opened the pressure will not go up past about 1 bar and you can hardly hear any water actually going into the system.
And it is leaking water out of the PRV pipe when it is on.

Any help on what might be going on would be much appreciated. Thank you!

 

[alarmguy123]

Bump

 

[ianmcd]

You need a better heating engineer , your EV needs pressurising, and there is absolutely no link between your EV and the PCB

 

[alarmguy123]

You need a better heating engineer , your EV needs pressurising, and there is absolutely no link between your EV and the PCB

Thanks. He did re-pressurise it when he came to do the service originally but the PCB did need changing as the boiler would not function properly and would not stay on - the screen was going mad and it would not stay on. But just quite a coincidence that the boiler was working absolutely fine and then suddenly the PCB breaks and then the boiler can't hold much pressure at the same time either.

 

[dilalio]

EV needs to be open to atmosphere to be properly recharged.

 

[Davie77]

Hi, I have the same issue with a Saunier Duvall F24E condensing combi losing pressure. It has gone from neding to be topped up every few weeks, to now every day. I have tightened the valves on the radiators and can't see any visible leaks outside of the boiler or on radiator joints etc.

I realise this thread is 18 months old but was wondering what happened with yours in the end and how did you resolve the issue?