faulty central heating control

mikeouk

I have a horstmann c21 central heating control,its just over 3years old,it was fitted by the builder before i moved in (new build property) I went to turn on my central heating last night and there is nothing on the display,it says in the booklet to press the set and copy buttons in if this happens, I tried it and the display comes on for about 5seconds then goes off again. The funny thing is,theres a single fuse box at the side of it, and when i checked there was no fuse in it, im wondering if the builder has never put one in and the control has been running on its back up battery all this time, I put a fuse in but this hasnt rectified it,,,so,,if the back up battery goes in a control can it be replaced or would i have to replace the whole unit. I rang horstmann and the guy i spoke to wasnt much use,he just said id have to replace the unit,,which hes bound to,,,,can anyone help?
cheers
mike

greyteam1959

Have a mooch around on here might answer your query
http://www.horstmann.co.uk/downloads.asp#Domestic