Hi all - hope you can help. We appear to have an airlock in the hot and cold water system. Water does not come out of either the hot or cold taps. İ have run maıns water through each tap and everything seems ok for a while then the problem reoccurs and water will not come out of either tap. The cold water tank in the loft is full up. Any suggestıons please? Thank you. PS. A shower pump runs off the bath taps to feed a power shower - I don't know if this is relevant?