I have a radiator in a large pressurised system in a youth hostel which is cold. When bled, hot water spurts out, and continues to spurt out whether either or both of the valves are shut off !?! Whilst the water is spurting out of the bleed hole, the radiatior warms up. When the bleed hole is closed, it cools down again. The inlet pipe is very hot.
What is going on?
What is going on?