"Low system water level" fault - Ariston Microgenus 23 MFFI


14 Jan 2016
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North London
United Kingdom
Ariston Microgenus 23 MFFI

The "Low system water level" lights up occasionally when using the kitchen sink hot water tap. Switching the boiler off and on again fixes the fault. The fault seems unpredictable, the boiler could be fine all day, then could shut down twice within a few minutes in the evening.
The mains water pressure is good and the boiler pressure is just over 1 bar. The heating system is working without any problems, as long as the boiler hasn't shut down from the warning.

What could be causing the fault? Could it be debris clogging one of the flow switches? Could the Main circuit flow switch require replacement?

Here is the boiler manual: http://www.ariston.com/uk/Homeowner/media/files/576_microGENUS_Installation.pdf
Here is the parts list: http://www.aristonboilerservicewales.co.uk/pdf/mgenus23_27_e04.pdf

Many thanks in advance.
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Take your pick....weak/blocked pump, partial blockage in the drillings to the primary flow switch diaphragm, a blockage elsewehere. The primary flow switch assembly itself are normally ok.
Thanks Gasguru. I'm wondering if it's a blockage somewhere because this started a few days ago after we lost all water in the whole area due to a Thames Water fault.
That would not normally affect you boiler as its a sealed system.

I don't usually find that model a very robust design in respect of the water parts.

There is probably some dirt and the pressure switch may be tired and rather out of calibration.

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Thanks Tony for your reply, I was actually planning on giving you a call in a bit. I'm in NW11, is that somewhere you cover (you're in NW10?) and have the time?

the pressure switch may be tired and rather out of calibration.
Also, just out of interest, I thought it might be a pressure switch blockage as you suggest, however in the parts list I only saw reference to an Air Pressure switch, rather than water pressure. Do Ariston call it something else?
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There seem to be two different designs of that model, one with a pressure switch and one with a flow switch.

But if it has a low pressure warning light then yours must have a low pressure switch.

I don't like any of them!

Its not a low water level but a low water pressure.

Silly translators!
Its not a low water level but a low water pressure.

Silly translators!
Ah, capisco!

Would you be willing to come to NW11 to take a look? If so, please let me know and I'll give you a call.
Thank you.
To discuss that you need to contact me from off the forum. Details in my profile.

But I am pretty busy until after Saturday.

  • Thanks
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