Boiler makes clicking noise and switches off before getting hot

[DIY67]

I have a Heatline C24 that has started to make a clicking/ticking noise every few seconds. The bar also moves on the dial a little eratic and it switches off before the rads get hot enough to the temp set on the thermostat. So it does eventually keep coming back on if left turned on but the rads stay luke warm. I have checked no air in rads and oulet pipe not frozen outside. I have also noticed of late that the bar is too low first thing so I have to raise it for it to start up. Then when it gets going the bar shoots up quite a bit higher ( but not in the red) The hot water works ok but something is causing the boiler to stop prematurely.

 

[John D v2.0]

The pressure should increase when the system is hot
Yours sounds like a restriction in the flow. Has anyone done any work on the system recently?
Could be sludge blocking things, try bleeding a radiator and see if the water is clear. Any water coming from a copper pipe outside?

 

[DIY67]

All new rads last year and water clear when fitted. Flowmaster thermostat was also fitted. Boiler was installed Oct 2010. Will check if pipe putside has water coming out and give rads a bleed

 

[DIY67]

Ok, I just checked it again and the clicking was in sync with the led over the symbol for low air pressure. Also the bar was flashing, although the reading on the gauge was showing the ideal recommended pressure ( between 1-2) but after a few mins the boiler stopped ticking and has stayed on so far, rads getting hot now. Is there anything I should still do, check ? I did hear a faint whooshing noise from in the bathroom every few seconds but that has also stopped.

 

[John D v2.0]

If it's low air pressure the must be an issue with the fan, flue or air flow sensor. This would need attention from a gas engineer.
A pro might be along soon who has experience of these boilers.

 

[DIY67]

I try and bleed the rads but just water comes out. But at the same time to bottom of them are cooler. There was no sludge in the system at the time they were newly installed a few months ago. The water was very clean. So should I empty the system and refill to get the air to the top of the rads for bleeding ?