Hello, I have a glow worm ultracom HXI 15 boiler. When's it is on CH cycle it runs but as soon as it reaches the set water temp of 66 degrees it cuts out. It then re starts once the water temperature has cooled. This it does continuously until house has reached temp. The pump in the airing cupbiard doesnt stop its only tge boiler. Which takes ages as it just keeps cutting out. It does not do this during the HW cycle. Many thanks in advance for any help.