Hi. Have had new combi boiler fitted. Plumbing has all been rerouted also due to building work. Have realised that when I turn kitchen cold tap off the boiler behaves as though a hot tap has been turned on ie the symbol that shows hot water is being drawn appears briefly and the boiler seems to cut out then reset itself to continue with the central heating. Is this normal ? - have had combi boiler for years and never knew any cold taps to affect the boiler like this.