CASTLE Hill School was closed yesterday after the under-floor heating system broke down.
The caretaker of the Newsome Road South school discovered the problem on his early morning round and immediately called in the technicians and alerted staff.
They manned the phones and managed to contact parents and carers of the 99 pupils, informing all of them of the closure before any arrived at school.
Some had set out on school buses which turned round and took them back home.
Engineers worked on the system throughout the day. Headteacher Gill Robinson said that the school was expected to reopen today.
Castle Hill School and Specialist College for Communication caters for three to 19-year-olds with severe or profound learning difficulties.
Many students also have complex needs linked to physical or health difficulties.