1)When I fill my boiler to just over 1 and a half bars and then switch the heating on the needle goes right to the top of 3 bars and discharges water out of the overflow pipe. When I switch the boiler off the needle goes well below 1 bar and I have to keep topping the water up.

2) I have also been advised that my hot water tap is running through my boiler?

3) When i use the hot water one of my radiator seems to get hot ?

I have checked for leaks and air blocks in all the radiators and they all seem ok. I have been advised that i need to replace the diverter vaulve and have been quoted £160.

Can someone please advise me.
many thanks Hash

Hashim, November 2006

No hot water but heatin works. Any idea

lee, July 2013

hoa do I repressurise it.I don't know which screw on the pipes underneath I turn to do this.Is it the main water tap on far left?

jane, December 2009

by the by, the boiler will not start unless the pressure is over half a bar.

engdes, May 2009

THE MOST COMMON PROBLEM WITH THIS DESIGN IS THE DIVERTER VALVE DIAPHRAM. THIS GOES FAULTY EVERY 2-3 YEARS AS THE RUBBER IS UNDER CONSTANT STRESS. THE SECOND MOST COMMON FAULT IS THE PUMP WHICH YOU CAN OFTEN GET REWORKING BY HITTING IT WITH THE WOODEN HANDLE OF A HAMMER. It cost £10 to fix the diaphram, if you know what you are doing.

engdes, May 2009

i have an ariston sx20 mffice, does anyone know how to relight the pilot light?..i have lost my manual and the instructions on the boiler were ripped off ..not sure if it was my children years ago..i not long ago had a new board put in ..after some months it wouldnt start up ..i pushed in the reset underneath the boiler and it started fine ..now its happened again and pushing the reset underneath does nothing and it looks like no pilot is lit, i think it needs relighting but i dont know how

david, February 2009

have a ariston sx20 mffice. no c/heating or hot water. the pilot light is off, although the warning light does not appear to be on. the pressure is at 0.5 bars. i know nothing about boilers, but my rental agency didnt fix it before christmas and are now closed for two weeks. and im in scotland and v.v cold.

i have tried following the instructions on the panel to relight the pilot but nothing is happening. incidentally i do not have an instruction manual! is there anything relatively simple i can do to try and fix?

how much would it cost approx to get it looked at? i've never had to deal with plumbers before!

btw im not blonde, but feel like it!x

sarah, December 2008

Your problem with the pressure is caused by a lack of air in your expansion vessel.The vessel is behind the boiler (nomally red).You need to remove the dust cap(same as car tyre)from the to of it and pump it up to 0.5 bar but you will need to remove any water pressure from the boiler.
The radiators heating when running water does sound like a faulty diverter.An origional ariston would probly cost around £120.00 and it's a bit of a sod to change,so price sounds about right.
Hope this helps

Pete 100% Heating ,Bristol 01454854067, November 2006