The expansion vessel is the large red thing behind the boiler with a car tyre type valve on the top. You can download the manual from the vokera website for more information. Push down the central pin of the car tyre type valve, a little moisture coming out is normal, it just needs pumping up again. Only replace is a significant trickle of water comes out (I would strongly suggest you try pumping it up first anyway though- they very seldom go wrong- the just go flat and need refilling with air- it takes a lot of pumping to refill a completely flat vessel.).
c.
November 2008