We have a 120FF Glowworm boiler with 16 radiators. It was installed about 7/8 years ago - three of radiators were added later. Radiators have thermostat valves but they are always on 5 becaue they never get hot enough. Any ideas. I've jujst turned the boiler setting up to maximum it was half way to see if that makes a difference. Any helpful suggestions out there. Also we are out at work allday and so heating is only on for about 4/5 hours a day at most.
Thanks

Try to bleed the system of air first. Then if that does not work post back.