I have recently installed a new Mira Event XS power shower into my upstairs bathroom. When in use for the first time each day, there is intermitant \\\'surging\\\' noise as the water feeds through the pump. Happens for a few moments then the full flow is on. I assume air must be getting into the supply pipe. I have connected the cold water plumbing directly to the cold tank in the attic. So the problem must be from the hot water plumbing/supply - also from the attic. The hot water tank is in the \\\'airing cupboard\\\' at the top of the stairs. Should I look for an alternative hot water pipe to take the supply from? Which and why? TIA for any info to resolve this.