Baxi 133HE Plus

[DibbleElmParc]

This one is driving me up the wall.

I have an issue with a Baxi 133HE Plus.

End result is that it goes in to fault and locks out.

I think it is heating the DHW up to an over temp state but don't let me lead you.......

OK what I can see................

Heating works fine.
Turn on a Tap
Boiler switches from CH to DHW.
Lamp for DHW goes on.
Burner light goes on. (all good so far..!)
Turn tap off.

The DHW lamp stays on.
The burner sometime continues to run but not always.
House gets cold..! as DHW is the only thing being heated.

The above is intermittent.. I can turn the tap on and off a few times with no problem.... Then......

I have changed the flow switch.
I believe I have check the Temp sensors.
( I have spares and they read the same values.)

Help.!!!! Its driving me up the wall.....

Thanks in advance......

 

[Baxmax]

p.c.b

 

[baxpoti]

I have changed the flow switch.

What was the part number?

 

[DibbleElmParc]

Thanks for the response....

Baxman....
I hope its not the PCB.. Is this a common fault..???

Baxpoti...
mmmmmmmmmmmmmmmmmmm
A little tail here.....!!
A ordered a 111793 flow switch. (think its for a 110HE)
It is not exactly the same from a pipe work point of view, but electrically it is the same.
I removed the switch section 4 screws, and exchanged it with the one in the boiler.
I think this should be OK. Its a perfect match at the switch end....

More info...............
With the old flow switch.
Turn off the boiler.
Measure resistance of switch - 15M ohm
Turn on tap
Turn off tap
Measure resistance of switch - 12K ohm

I disconnected the switch to PCB and made the connection manually when the DHW was running. (Shorted terminals). Worked fine.
This is why I changed the flow switch.

Help..!! and thanks again.....