Then the hot water stopped coming out of the taps. The boiler was still on, the radiators were still hot but no hat water. So I tried hot tap again, it ran for about 30 seconds then stopped. So in the bathroom instead of a bath I filled a basin full of water and washed in that.
We phoned landlord and he said "I am in Carmarthen, see u in a bit", came round, did some adjustments which matched the ones we had tried but the hot water is back now.
The magic touch, I think
(noisy link)