I would thoroughly recommend UFH and especially Doug. The fault was quickly diagnosed (faulty thermostat). A new one was fitted and Doug explained how it worked very clearly (good for me as anything technical is baffling as far as I am concerned)! Although the cost seemed high, to get an electrician to diagnose and fit would probably have cost the same so I am very pleased the underfloor heating is working again in the conservatory. He stayed as well while it got warmer. When he left at 2pm the temp of the floor was 15c - now after 4 hours it is 19.4c. About one degree per hour. Thank you Doug (and Vicky who fixed the appointment). Very good company.