This customer had a radiator that he couldn’t bleed but also wouldn’t heat up past half way.
He had already figured out the price for replacing his broken radiator when I arrived.
Luckily for him I’ve seen this many times and it’s easy to diagnose where the fault is.
When you bleed a radiator the air has to come out of a opening inside the bleed point. On this particular type of bleed point (myson radiators) the opening is very small. As it’s so small it very easily gets blocked up by sludge or dirt in the system.
Even when the bleed pin was completely removed there was still no air or water coming out.
However when I turned the whole bleed point fitting with my small adjustable spanner air (followed by water) did come out. Proving that there was no fault with the radiator itself.
The simple solution to this problem is to poke a fine needle into the hole. This breaks the dirt crust and allows the water and air to come out. First you must turn off the valves to the radiator and put a tray and some towels under to catch any spilt water.
As soon as you break the dirt the air will come out (quite fast). The idea is to get the screw back into the fitting as fast as you can (without cross threading it) so no water is spilt. The time you have to do this depends on how much air is in the radiator and how much pressure is in the system.
The drip tray and towels are your very best friend if you can’t work quick enough.