potterton lynx 2 combi

[Rich425t]

Central heating ok and hot water hot, but when I turn the hot water tap off, the boiler keeps on going and boils itself to death, the water heating light stays on for a short while after it calms itself! When the hot water tap upstairs is turned on 1/2 to full its very noisey! Is this to do with my problem? Hope someone can help! Cheers rich.

 

[Gasguru]

Could be trapped air in the pipes or dead legs in the system - have you had any new plumbing?

Alternatively the boiler water flow switch may be sticking (although I have yet to change one so far). Easy test with a multimeter.

The noisy tap may have a worn washer.

 

[Rich425t]

How do I check If my Water flow switch is working correctly? The boiler heats up the hot water OK, but when the tap is closed, the boiler carries on heating!
Also if I have a air lock how do I get rid of it?

 

[Agile]

With the power off, see if the diverter valve pin comes out and retracts immediately the tap is turned off. Probably it doesn't !

If it does then you would need to electrically check the switches that the pin activates.

If both of those are fine then it could be a PCB fault but that would be very unusual.

Tony

 

[Rich425t]

Thanks for info, diverter valve was changed back in jan 07, could it be the pcb?

 

[Agile]

Thanks for info, diverter valve was changed back in jan 07, could it be the pcb?

Thats totally irrelevant when it was changed!

Please check what I asked if you want to find the fault!

Tony

 

[bones001]

there is no diverter on a lynx2 there is a flow switch on the right hand side right at the back with a grey (i think) wire coming off it and these often stick and need replacing and can be a bit of a nightmare to change. to check it just follow the wire from the flowswitch pull the connection off the board while the fault is occuring and if the burner shuts off the flow switch is goosed

 

[Agile]

Thats a good point bones! But how was his diverter valve changed:-

Thanks for info, diverter valve was changed back in jan 07, could it be the pcb?

As bones has corrected my oversight, your boiler has a four pipe heat exchanger and relies on a DHW flow switch which is apparently sticking on after a DHW demand.

Probably needs replacing!

Tony