Vokera linea 24 losing Pressure - Solved

[Dazzh]

Hi All,

September 2017 I had the expansion vessel, PRV and AAV replaced as the boiler, Vokera linea 24, was losing pressure and water coming out of the schrader valve.

Everything was fine for 4 months however it started losing pressure again, this time about .5bar every 24hrs.

I checked the pressure in the expansion vessel and there was nothing in it.

I opened a bleed valve in a radiator and inflated the expansion vessel to .8bar, as per the manufacturers recommendations, closed the bleed valve and repressurissed the boiler to 1.5bar.

However its still losing pressure. I've checked all the radiators and there are no leaks. I've also checked the outside overflow, where it would discharge water if it was a faulty prv but its dry. I tied a bag around the overflow and there was nothing in it after 24hrs. There are no leaks from the boiler.

I then drained the boiler and checked the pressure in the EV which was .45bar after only 4 days of repressurising it.

The firm that carried out the work did not supply the EV as their supplier did not stock it. I purchased it new elsewhere.

Does it sound like the EV is faulty or is there something I should check.

Thanks

 

[flameport]

If the pressure in the EV reduces over time, then the valve is probably leaking air.

However that does not explain the loss of pressure in the rest of the system - for that to happen, water is leaking somewhere.

 

[Dazzh]

Thanks for the reply.
I've put some washing liquid on the valve and there's no sign of air coming out.
No sign of damp patches on any ceilings which I would expect if its losing .5bar every 24hrs. The only place I've not checked is under the floor, this was a last resort but may now need doing.

 

[Madrab]

Isolate the boiler flow and return, if it still loses pressure then it's internal to the boiler, if it doesn't and you open the valves and it then drops, then it's out in the system somewhere. Allows you to narrow down where to focus on.

 

[Dazzh]

Thanks @Madrab.
Once I've closed the valves do I:

1. Leave the boiler on CH/HW.
2. Leave it on HW only.
3. Turn it off.

Thanks

 

[Madrab]

Unfortunately you need to have it turned off.

 

[Dazzh]

Thanks again @Madrab.
Not a problem will turn off, isolate valves and see how it goes.

 

[Dazzh]

Well finally got to the bottom of it.
I checked the pipes and could not find any leaks.
Upon reading other threads some suggest the main heat exchanger could be leaking. However there was never any sign of water under the boiler.
On looking through the inspection glass I could see some of the insulation in the combustion chamber was peeling and black.
I don't mind tackling some DIY jobs but will not go anywhere near anything to do with gas (Combustion chamber), better to leave this to the experts.
Local Gas Safe Engineer came out and after what I had told him opened up the combustion chamber and found a small leak in the Main Heat Exchanger and the insulation damp.
Parts replaced and now everything is back to normal.

Thanks to all for their replies.