Ariston/Intesa combi dwh problem

DHW fires up but shuts down within seconds.

Water gets quite (too?) hot but little comes out of tap and formerly cold radiator out pipe gets hot.

Central heating works absolutely fine but occasionally looses a bit of pressure (this may be a small amount of water as the system is very small with only 4 radiators on most of the time).

I have recently descaled kettling exchanger with Sentinel x800.

Assuming that the diverter might be failing/blocked. Has an electronic actuator. What is the best thing to check first?

Any ideas gratefully received.

Actuator on page 41:
http://www.ariston.co.uk/uploads/doc4836d8f6570d6.pdf


Cheers,
Jonathan

hi.

"Water gets quite (too?) hot but little comes out of tap", little hot water comes out tap, then goes cold? or the flow of water is poor?

When you create a hot water demand make sure the flow is around 9-10l/min, on dropping the front panel of the boiler ( 2 screws underneath), to the right hand side looking in they're should be a small usually black plastic switch, they're should be a red light continuously lit whilst the hot water top is running, if not the boiler wont fire.

Assuming this switch is lit whilst the tap is on if the burner is cutting out, they're are a number of things that spring to mind, possibly the venturi needing cleaned (RGI), or aps dropping out (RGI), however if your confident they're is a certain amount of heat travelling through the heating circuit leave the tap on for a good 20 mins and see if radiators start to heat up if so, you need to check the actuator is firstly in the hw position (flush with the plastic), if it is then you will need a new service kit for that diverter section, if not follow your installation instruction booklet to check the correct voltages at the actuator.

Sorry to be unclear.

Water flow out of hot tap is good, just cold water. Boiler is firing fine.

Thanks for the reply.