Baxi Duo-Tec Combi HE. Hall effect sensor.

[DGarethJ]

This is an intermittent problem which is gradually getting worse.
When any of the hot water outlets is used, however briefly - The Hall effect sensor continues to glow red after the water is switched off. The Green domestic hot water flow light also continues to glow, there is definately no water flowing yet the hall effect sensor thinks there is.
While in this condition, should the thermostat demand the central heating be turned on then this request will be denied.
after a varying period of time the sensor suddenly switches off and the central heating then comes on. However this time period is getting longer and longer sometimes as long as an hour.
I used to be able to "cure" the condition by giving a few seconds burst of hot water from one of the taps but this is getting more and more difficult.
I have replaced the Hall Effect Sensor but the fault remains.
The diverter valve was replaced about a year ago and the installation is about 4 years old.
Can anyone give any help on this fault ? What exactly does the Hall sensor detect ?

 

[ScottishGasMan]

Its not a true hall effect sensor in these boilers. More like a magnetic reed switch. the brass where the sensor clips round, in there is a sort of float that moves up and down with a magnet in it activating the sensor (its almost never the sensor its self at fault)

sounds like yours is sticking. Can be stripped and cleaned but are prone to breaking trying to get em out.

 

[DGarethJ]

Thanks ScottishGasMan what you say makes very good sense - would I need to remove the Hydraulic inlet assembly to get at the float ? Its very inaccessible - and what would you recommend removing in order to get at the inlet assembly ?

 

[ScottishGasMan]

When the Plastic flow switch is removed you will see the brass section that it clips onto is hexagonal shaped, a tight fitting socket turned anti clockwise over it will unscrew it (the mains water needs to be off or your going to get very wet around now)

I don't recommend anyone to be opening and working inside their own boiler, much smarter to get someone qualified with experience of the particular unit (Baxi for example) I'm just answering your question of whats in there lol

 

[Laticsforlife]

I know it's very old now, but how did you get on with this as it sounds exactly like my issue now.

Sounds like a simple fix in a not-so-simple location.