So it doesn't respond to the boiler thermostat setting? i.e. if you turn it down low it makes no difference?
If so, expect a thermistor or PCB potentiometer problem.
The drayton normally requires a three wire connection, common, call & satisfied. What sort of motorised valve(s) do you have? If you have 2 zone valves, then you can just use the common & call terminals.
The EP2001 is obsolete. You might want to consider fitting an EP2002 which will go straight on the existing back plate. Or an EP2.
They are both still available.
The lazy builders and hapless halfwits are still waiting for a photo from the enlightened one.
Mind you, I've got a bit of wire that I have no idea of its function. God knows what the idiotic, useless electrician was thinking when he installed it, the bodger.
You need a competent heating engineer, not a sparks.
It would take someone with a multimeter less than 5 mins to work out what is causing the problem.
How much did you pay the electrician?
Well, it would seem that the correct answer to the Op's question is to shorten the hose so that it cannot under any circumstances rest in the bowl. If the minimum separation is maintained there is no risk of contamination.
All I would say is good luck to using that in the middle of a UK...
Can someone cite a verifiable source of an incidence of contamination resulting from the use of one of these over the rim appliances?
I am finding it hard to believe that the UK has the jump over countries where there are literally millions of these things fitted and are in constant use...
Well there is an air break isn't there? Or do you think that the users of a device designed to keep them fastidously clean just dump the hose in the toilet bowl after using it?