We have 3 years old Vaillant ecomax 824/2 E bolier. The problems is that water level keeps going down (below 1 bar) with fault code F25. If I refill the system again then reset, the bolier starts to work but I have to do this every 2-3 days. I couldn't find any leakage in my house. Please would you kindly let me know what the problem is.
It's probably the pressure relief valve or expansion vessel ours did this at 4 yrs old. Never had a problem with it til then.
Charlie, November 2010
Sorry I meant the PRV. The usual cause of this is when the presure drops in the expansion vessel. This can be checked with a tyre presure guage. If this is less than 1 bar top it up using a pump
Daddy Pops, February 2010
Like the others have mentioned. It usually the APS. Its a common problem with vaillant 824 & 828
Daddy Pops, February 2010
We have had similar problems that were cured by replacing the pressure relief valve. Quick & simple, not very expensive.
Hope that helps
David, February 2010
have u looked outside to see if overflow pipe is leaking its the copper one
