We have a shower block on a campsite. Sometimes when hot water is called for in the showers or hot taps nothing comes out. We have two industrial oil boilers, and the water is supplied by gravity from tanks above. Three pumps on the system opperate the male/female showers and hot taps. Sometimes the taps splutter as if there is air in the system. There is a pipe coming off after the boilers going back to the water tank for expansion. Im wandering if air is getting into the system via this pipe if so is there a non return valve that can be fitted if this is the problem. The pipework is 28mm.
