In the kitchen there is a boiler above it in the airing cupboard next to the hot water tank is a metal box on the wall 4 1/4"x 5 1/4" marked Stachwell Sunvac there is a relay+ 5 amp fuse and a board. Below it on the pipe is a small metal box marked Douval says domestic water with arrow pointing up and central heating with an arrow pointing down .Attached to the hot water tank there is a clock that goes from 40 to 90 Stachwell+ Atchwell on the front . i know they are the controls for hot water etc .but can you tell me what they are called . as i am trying to cost to replace . I am told it will cost £300 to replace ?