They'd managed to leave the immersion switched on for about a day, and it had not only heated the 120l tank, but the large cold storage tank above it (I estimate it must be 250 or 300l at least) to a rather scary temperature. After that, they said it didn't do any better than lukewarm, and then packed up altogether.
Well, after spending couple of weeks phoning him to get access to the flat (suspect he'd been avoiding my calls, he owed us rent....) and sorted the problem out.
I'd been idly speculating upon what the problem might have been whilst waiting to do the job, perhaps the thermostat had packed up, etc etc. Heater was open circuit when tested, so drained the tank down and whacked in a replacement, no problems.
But, can anyone spot what could have been the problem with the heater....
The immersion heater is now connected via a timer...!!!
-- Richard Sampson
email me at richard at olifant d-ot co do-t uk