"The OP has enjoyed a good whinge. Most right thinking folk
would have simply swapped the powerhead and enjoyed the rest of the
day free."

"but I don't recall hearing about microswitch problems until now."

And, presumably, you don't want to hear about them?
You like forking out £60's every two years to buy the same faulty kit over
and over.


"There's no hunting in the mid position unless something's broken
or wasn't wired properly."

"It's probably a symptom of some failure, such as one of
the contacts not working"

Quite. :-(

I cannot claim wide experience of CH systems, but both those I have had to
look at, had had a lot of money thrown at them without identifying the
fault, before I sat down to try and sort them out myself, and both had
failed in exactly the same way due to exactly the same burned semi-micro
switches - of which I have pictures if anyone is still in doubt.

As I indicated, the majority of users are probably quite unaware when their
valves are not working properly: the rads and water still get hot when their
'on' cycles are lit: only the room thermostat gives the game away when it
appears to fail to override the programmer.

Trust these devices if you must.
I don't have the luxury of being able to afford to.
Perhaps there are some people reading uk.d-i-y who aren't moneyed experts
and this information might save them some time and money.
If there are no non-rich-experts using this forum, and anyone else who takes
the time to offer up useful information is just going to be sniped at, what
is it for?

S