Horstmann Electric 7 only works with boost

[KHayes]

Hi all, any suggestions, as my Horstmann only works when boost is switch on, even though an electrician has checked it two times! I do believe the settings are correct, any suggestions as to why this might be? Should the 'timed boost' have the black arrow there when the red button is on also?

Thanks

 

[DPG]

Welcome to the forum!
There are a lot of threads on here about Horstman timers, I'd have a search and you will probably find your answer.

 

[Avo Mk8]

Hi all, any suggestions, as my Horstmann only works when boost is switch on, even though an electrician has checked it two times!

By "only works when the boost is switched on", do you mean you only get hot water when you use the boost button, and you don't get hot water if you leave the Horstmann to do it's normal thing?
A common reason for this problem is failure of the lower immersion heater in your cylinder, either because the over temperature stat has tripped, or the immersion element has become open circuit.
it's not necessarily a failure of the Horstmann.
But I would have expected an electrician to check that the immersion heater element was OK! Do you know if he did?
If he just checked that there was a voltage across the immersion terminals, that wouldn't have checked the element!

I do believe the settings are correct, any suggestions as to why this might be? Should the 'timed boost' have the black arrow there when the red button is on also?

I believe the black arrow would be on "run" under normal circumstances, even when you press the boost button, but I could be mis-remembering!

 

[Dartlec]

As well as checking the lower immersion heater element (a resistant test across it should show whether it is still functioning), it's also possible that the thermostat heat reset has tripped.

I've found it quite common, especially if the immersion is in a small cupboard and other things are stored in there.

If you can show a picture of the lower immersion heater with the cover removed (but make sure the horstmann is set to OFF first), then it might be clearer whether there is a problem there that needs to be resolved.