Students at Leith Academy have told how “intolerable” conditions in some classrooms forced teachers to bring in emergency gas heaters.
Chilly youngsters have taken to wearing coats in lessons and during prelim exams currently taking place at the school.
At least two pupils have been kept away from classes by their parents since the boiler breakdown on Monday.
But education chiefs have insisted the school is safe and remains open.
One student said the heating system had been faulty for the last three years and claimed her English exam had been hampered by trying to concentrate in icy temperatures.
“We all came out shivering,” she said.
“The school keeps saying the boilers have gone but they have not done anything to get them going.
“You can’t concentrate and teachers keep asking you to take your jacket off.
“I had a preliminary exam in English on Monday and my hand was aching with the cold.
“My finger nails were going blue. I feel I would have got more done if the room was at a reasonable temperature. It’s intolerable.”
It is hoped heating engineers will be able to repair the faulty boiler today, with the mercury set to plummet to just 3C.
Chas Booth, Green councillor for Leith, said the heating woes had given rise to a “deeply unfortunate situation”.
He said: “It underlines the importance of ensuring that we invest in proper maintenance of our school estate and invest in proper heat and energy efficiencies.
“The priority for Leith Academy must be fixing the current problem as soon as possible so that these intolerable circumstances don’t continue for any longer.”
It is understood the level of staff absences has not risen in recent days despite the cold conditions.
Pupils have reported that some teachers were leaving windows slightly ajar to expel “fumes” from gas heaters being blamed for causing headaches.
One source said: “The kids are being told to sit in their classes with their coats on by their tutor teachers.
“Then when they go to certain classes teachers are complaining to them to take their coats off in freezing temperatures.
“Some teachers have told the kids to tell their parents to call the council so they can get the boiler fixed.”
Lindsay Law, who represents parents on the council’s education, children and families committee, said: “Parents would expect that children are safe in school, and I think all parents would expect that children are warm as well.”
National guidelines insist that the minimum classroom temperature must reach at least 17C within an hour of pupils taking their seats at the start of the school day.
The council was today unable to provide readings from thermometers confirming the temperatures had reached acceptable levels.
But it insisted classroom conditions had not fallen below that threshold.
A council spokesman said: “We are aware of the heating issues at Leith Academy and have engineers on-site installing a replacement boiler.
“In the meantime we have put in place temporary measures and apologise for any inconvenience caused.
“Staff have been working extremely hard to ensure the school continues to run as normal.”