Vizo 24 internal fuses keep blowing

[Jimboben]

Any ideas would be appreciated.

I have isolated the pump, fan and gas valve. Initially, the internal 2 amps fuses hold for about 10 minutes(boiler not running) and 'bar' warning light flashes but the pressure is fine. then blow. Replacement fuses blow immediately.
It appears as though some resistance builds up?

 

[mr-crs]

Hi its probably the divertor valve leaking into the actuator and causing an overload,I dont want to be the bearer of bad news but the boards are often damaged when this happens so it could be an expensive fix im afraid. Paul

 

[Jimboben]

Thanks for a quick reply mr-crs.
I will disconnect the 3 way valve from the PCB and see if the fuses blow.

 

[Jimboben]

Thanks mr-crs.

Changed the actuator and that stopped the fuses blowing.

Fitted a new water pressure sensor and that cleared the fault on the panel.

System still not right though.

The DHW heats the water but I can feel the water temperature fluctuating at the tap. The heating fires for 1 minute approx then shuts off for 1 minute approx and carries on like this for 10/15 minutes until the internal fuses blow.

Any further suggestions would be welcome.

 

[Gasguru]

Did you check the old actuator for water damage...the fuses often blow due to water leaking from the diverter spindle gland into the actuator. Perhaps this has now happened with the new one.

And the spindle gland often leaks due to debris in the system water whichin turn results in a blocked plate heat exchanger that can lead to hot water temperature cycling.

Heatlines are nearly always installed by cowboys and the systems are generally poor.

 

[Agile]

Little point in replacing the diverter valve motor if you dont change the pin gland.

The unstable hot water is probably just the usual blocked plate HE.

Tony

 

[Jimboben]

Thanks to everybody for their replies.

The boiler is now running again.

The fault appeared to be that that one of the leads into the actuator had fried it's insulation and the bare wire must have shorted out.

The lead has been repaired and the seal in the valve replaced. A new thermistor was also fitted.