Vaillant combi - "aqua" sensor Q

[Jethro_uk]

With the shiny non-leaking diverter valve, the hot water output still seems to be temperamental.

More digging suggests the "Aqua sensor" may be playing up. A couple of YouTube clips, and pictures online suggest this is some sort of plastic impeller that reports the rate of water flow to the control unit which then fires the boiler to the correct level to deliver hot water.

I am guessing there's some sort of magnet or hall effect sensor that translates speed to signal ?

Also I presume something in this plastic distorts over time and affects it's fit in the housing ? On the basis you can get replacements ?

Looking for any experience or advice on this - in particular whether my suspicion that it's possible to simply remove the impeller from the housing by removing an internal circlip ?

As an aside, would it not have been possible to have created some sort of shaped assembly that forced the water through a venturi and simply picked up the frequency via a pizeo transducer ? That is with no ****ing moving parts ?

[Fredxx]

I only know Baxi boilers to this level of detail and they employ either a vane or an impeller.

The impeller is the version I currently have, and have found crud stopping it turning. The plastic housing appears stable and didn't think it's likely to distort to pinch the impeller shaft.

There might be a small PCB located close-by with a hall effect sensor. Waving a magnet close by can often confuse the boiler into thinking there is flow to see if the boiler will fire up before dismantling the area.

Good luck.