Ariston Microgenus 27 leaking motorised valve

[Whiteye]

We have an Ariston MicroGenus 27 boiler fitted in our house, the motorised valve is leaking, the leak appears to be coming from the upper casing, when I removed the electrical connection the water appears to be pooling through the 3 prongs on the motorised valve and running down the diverter valve body and dripping out of the bottom of the boiler.

Is it simply a case of unclipping the (now rusty) spring clip, removing the motorised head and replacing with a new part and spring clip or is there something more sinister going on? I'm assuming I will need to drain the system down before replacing the motorised valve?

Thanks in advance...

James

 

[Gasguru]

Bit more to it than that and often as result of poor or contaminated system water (eg cleaner chemical left in).

So far you've been lucky. Often if the motor head is wet the actuator switches inside become waterlogged and blow the pcb fuses.

The gland seal on the brass diverter block is leaking. Check the thermister pins below have also not corroded.

The best course would be to replace the brass diverter valve, however you may be able to swap just the gland seal although I don't recommend it.

If you carefully prise apart the motor head you can dry it out. If the spring clip is too rusty it will need replacing. If Ariston don't do it as a seperate part get it from Biasi.

You will need to drain the boiler, check/re-charge the expansion vessel, replace the auto air vent if there is any sign of leakage. The new diverter (flowgroup) won't come with the "main circuit flowswitch" assembly. This is the assembly on the front. Replace that as these often leak.

You will also need 4 plate heat exchanger O rings and it's worth getting a couple of bypass O rings. The other diverter seals are standard 1/2 and 3/4 fibre washers.

 

[Whiteye]

Thank you Gasguru, some very helpful info there, seems like there's quite a bit of work to do, but cross-referencing it with the boiler instructions it should be pretty straight forward.

As you say, I think we've been quite lucky as we've caught it before the water shorted anything out and started blowing the fuses on the PCB.

I may, if it's OK post again once the parts have arrived and I begin stripping & replacing things.

Cheers!