This morning I have been rather alarmed to find that a large blister has formed in the foam insulation surrounding my hot water tank (cylinder?). There seemed to be liquid around its base below the blister. On careful investigation the liquid seemed to be a grease not water? I carefully cut out a few square inches of the insulation in the centre of the blister. The copper beneath looked fine and it was obvious the foam insulation had separated from the copper.
Just a few days ago I realigned the pipework from the boiler to the cylinder because its layout caused air to be trapped in the hot water circuit (it is gravity fed). Since then the hot water system has been performing orders of magnitude better than before - plenty of hot water generated in the space of an hour rather than just enough hot water after 3 hours!
Is there a likely connection between these 2 events. I should say the cylinder is about 10 years old and, yes, we have suffered its poor performance for that long.
How worried about all this should I be?
[BTW It was a side comment in a posting on this group, suggesting bleeding the circuit by loosening the connection from the boiler to the cylinder, which allowed me to test what I had suspected for a long time. Every time I bled the circuit in this way there was lots of bubbly hissing noise then solid water sound and the system subsequently performed well for a day or two.]Apologies this has got a bit longer than I intended.
Frank