I have a glowworm Micron 80FF.
I put the heating on, radiator 1 which is small heated up within about 3 minutes, number 2 went hot on the sides (big double one) cold on the whole middle section. Number 3 had no heat. I left it on for about 20 minutes.
Does that sound like sludge?
Have an 80FF boiler, about 8 or 10 years old. Works brilliant every morning. In the evening it will not stay on for more than 10 minutes, then the reset light comes on. Good old British Gas tells me that it is sludge and offered to take £700 and give me a magnet thing and a...