EVERY MORNING BOILER LOOSES PREASURE OVER KNIGHT, IN THE MORNING I TOP UP THE PREASURE TO 1 BAR ,FIRES UP OK AFTER 15 OR 20 MINUTES PREASURE GOES PAST 3 BAR THEN STARTS LETTING WATER OUT OF PREASURE RELIEF VALVE. RUNS OK ALL DAY BUT HAVE TO TOP IT UP EVERY MORNING .ALLWAYS GOES PAST 3 BAR EVERY MORNING. WATER IS BEING EMPTED BECAUSE OF PREASURE BUILD UP IN MORNING. HAVE CHANGED THERMISTERS AND OVERHEAT STAT.
as T says, new expansion vessel required and id stick a new pr valve on as well. vessel could be flat but generally they knacked. find valve on vessel and push pin in just like bike valve, if you get nothing out try re-charging it, if water comes out replace it.
iain
April 2008
Your pressure is going above 3bar and the 'safety' valve lifts at 3 bar to allow pressure out, causing your water loss, and a lot of times, dirt gets caught under the seat of the valve, so it keeps passing water.
The cause of the pressure rise is your inital problem, either your expansion vessel has failed and needs replacing or it need charging. Also the safety valve needs to be dismantled and cleaned.
T
April 2008
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