Eratic hot water at taps

[Fresh]

Hi,

I have an indirect hot water system and when I switch on the hot tap in both bathrooms the water is boiling hot and very eratic. It seems like there is air in the system, could it be coming from the open vent pipe?
The kitchen tap works fine.

Would it be a good idea to change the vent pipe from 22mm up to 28mm?

 

[justlead1]

Hi Changing the vent pipe will have no effect. If the bath tap runs water for say 10 seconds and then a spluttering of air, then water again and so on the problem is the cold feed to the cylinder. It either under sized (increase to 28 mm)or part blocked with corrosion / dezincifcation and alike. Check the cold water storage cistern for obstructions to cold feed and fittings, valve etc down stream to cylinder. Good Luck