Vokera Compact 28 works for a while then makes hissing sound

[AlanLeeds]

Hi All
Some help would really be appreciated,
The Boiler is approx 4 - 5 years old

When the boiler is working for heating it starts making a noise like a boiling kettle after say five minutes of use, if i leave it like this the boiler
turns itself off for a while then fires back up it can go on like this for half hour os so before it finally stops working and a red LED appears on the front panel, i then after reset the boiler. The only way i can get the boiler to work without shutting itself down is to turn the temperature dial to minimum all the radiators do get warm but not hot in this setting. The Hot water works fine no problems at all.

This has been like this for over a week, it happened after i changed our kitchen radiator. i shut all radiators off and drained down the system changed one bit of pipework (new radiator slightly longer than the old one). filled system back up via the filling loop open all radiators and bled them got pressure in system to just over 1 and now have this problem.

regards

Alan

 

[kevplumb]

is the auto air vent on the boiler open

 

[AlanLeeds]

Hi Kev
Quick reply thanks
yes it is
Alan

 

[kevplumb]

going by your description you have a flow restriction

1 are the isolation valves fully open under the boiler

2 is the diverter valve changing over properly

 

[AlanLeeds]

Hi
Yes both the valves are fully open,

im not sure what you mean by diverter, i have looked on the manual and i can see item 7 a by-pass valve could this be it ?(see Pic) if so how do i check its operation ? with the boiler running in heating mode with the temp dial at its lowest i do get hot water from the tap as normal does this show the diverter valve is working ? thanks for your help so far

Alan

Untitled

• AlanLeeds
• 12 May 2009
• 1

 

[BingoBongo]

is the pump running

 

[AlanLeeds]

Hi BingoBongo
Yes the pump is running, as i mentioned earlier in the post all the radiators are working all be at a lowerer temp cos of the setting at the boiler at the moment....thanks for your input any other ideas spring to mind

cheers
Alan

 

[bellairaphon]

are you have problems with low pressure too??? do u keep having to re pressurise.

 

[AlanLeeds]

Hi bellairaphon

no problems with the pressure set at just over 1 bar have not had to top up at all

regards

Alan

 

[kevplumb]

ok FWIW i think the diverter is playing silly boogers

 

[AlanLeeds]

hi again kev
FWIW what does this mean
the diverter playing silly buggers is it the part in the pic ?

Alan

 

[kevplumb]

For What Its Worth

like i said i think its down to water not getting away

if you have an se then i'm talking out of my ass

 

[AlanLeeds]

hi kev

ok so is the diverter valve the one in the pic (item 7 By-pass valve) ?
cheers

Alan

 

[bellairaphon]

i think faulty ntc on the central heating side. not registering the temp correctly n the overheat kicking in.... but ive had a trouble with one of these bad boys quite reliable apart from a few ntc's heat exchanger ( when no pressure reducing valve fitted ) n them ignition boards n the filter on the dhw... oh the hose from the expansion to the pump block getting glogged up....

 

[kevplumb]

well thats me telt