Hi I have a gravity system two large cold water tanks in loft a pump in bottom
of airing cupboard feeds the en suite shower been working fine for years pump
is fitted correctly with feeds as should be in 22 mm copper special flange in
top of hot water cylinder so I recently added another shower room and fitted
another pump in loft which is digital with an integeral pump I took it of the
domestic hot water about six inches under the tea for the house hot water and
another feed from cold tank in loft this shower works fine with no problems
but about every two weeks the existing pumped shower gets an air lock on the
hot side Ive done all the checks for cavitation etc but all seems ok any
ideas ?

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