ideal w rs460?

Hi there' im a electrician and have been asked to replace a programmer for this boiler ideal w rs460 which was installed in 1984.
I replaced the programmer and now I cant turn the water on without the heating coming??? There no motorised valve or cylinder stat and has only 3 terminals at boiler and had a separate pump connection, I really cant get my head around this one. the customers said it worked separately before. please help