Help! No hot water upstairs!

[marshalls851]

My hot water was fine on Saturday, and then Sunday I had boiling hot water downstairs but when I ran the shower, the hot water started hot but faded to cold.

I have a combi boiler and the shower runs from a mixer on the taps. Have checked that the heating is ok and it is, have checked the pressure on the boiler and that's fine too. As I said, I have hot water downstairs and I can get intermitent hot water on the tap in the bathroom too but then that also fades.

Help!

 

[theheatexperts]

what combi boiler do you have and also mixer taps can become a problem with combis,as they can send a back feed of cold water to the boiler when they begin to go faulty, either that or if your ht water works with a diaghram it may be slightly perished and need replacing, another solution would be to correct the flow rate of the incoming mains cold supply to the boiler

 

[m1key00]

more than likely the diaphragm wearing out, works downstairs because taps are higher pressure, enough to turn on DHW on boiler. Lower pressure upstairs not enough to move perrished diaphragm.