Vaillant excited 831 pressure query

[KOTN]

Hi folks,

I've an ecotec 831, serviced annually, generally good working order - no issues noted at services.

Pressure tends to be stable on the whole, but a month ago I was away from home for a week so had the system turned off. Pressure would have been about 1.3, cold.

Came back and noticed that the pressure was 0.8. No evidence of leaks anywhere in pipes or boiler, so topped up to 1.4 and it's been stable since. Heating not being used since, but calling for hot water several times a day.

Just been away from home again since Friday, so three full days out. Pressure dropped to 1.1. Again, no evidence of water.

Ran the HW, pressure increased a little whilst running then dropped back to 1.1.

I topped up again and the pressure seemed to rise rapidly whilst doing so, from 1.1 to 1.5 in 3-4 secs.

Any idea why I'd be losing so much pressure when the system isn't in use for several days?

Thank you.

 

[Johntheo5]

If the pressure rises very rapidly then the E.vessel may need recharging at the air end but if so you should see the pressure rising above normal with all systems hot, maybe 2.6/2.8 bar vs say 1.8/2.2 bar.

 

[KOTN]

From say 1.4 it tends to rise to about 2, 2.1 maybe with heating on. Thanks though.

 

[Johntheo5]

Maybe just keep a eye on it, if air side leaking the final pressure when hot will keep rising for the same initial cold pressure.