Hi - the hot water on my Vaillant Sine 18 only comes on now when the central heating is on (apart from very rare occasions). I don't know if this is relevant, but the hot water flow also seems reduced. An engineer looked at it - though he didn't go inside - and says I may need a new diaphragm, but he seemed dismissive of the reduced flow. He also talked about the wax capsule. Does he sound right? Does anyone have any ideas please?
Thanks in advance for any help
Thanks in advance for any help