Ferroli Sigma 60 problem

[phillips900]

Evening all.

I'm new here so I hope I don't end up breaking any rules.

I recently moved to a new house which has a Ferroli sigma 60 boiler. Now the boiler does work but not all the time. It doesn't matter if heating or hw or both are calling for heat, it will only seem to fire and heat the water in the system once. It won't cycle to get the rooms or the cylinder up to temperature. Sometimes it will work if I turn the controls off and back on and sometimes I will have to leave it for an hour before the boiler will refire. I have been told by several people that it could be a boiler stat problem. Is this something I am able to tackle myself or do I need to get a gas safe engineer in to do this? Is there any tests I can do to narrow down what is causing the problem?

Many thanks

 

[Tibbot]

Check the pump on the system works.

 

[phillips900]

Yeah the pump is definitely working. Have tried it on all 3 speeds.

 

[Tibbot]

Have you had the screw out and checked the impellor moving?

 

[phillips900]

Yes the shaft is free as a bird.

 

[Tibbot]

You need to check heat passes both sides of pump. Then all external controls, system full of water with no airlocks. If boiler control stat was faulty it'd go to overheat, then you'd be re-setting it.

 

[phillips900]

The system was drained last week so I could fit a new radiator and it has all been refilled and bled. The feed and return to the boiler are both hot after it shuts down so I don't think there is a blockage. From what I can find on the net the boiler has a temp sensor and a overheat cut off. If I hit the reset set button on the boiler it still doesn't fire up. It seems to only work when I switch if off from the controls and back on that it will work. But it doesn't work every time.

 

[Tibbot]

If you've drained the system, then there's your answer. The system is not properly filled with all air removed.

 

[phillips900]

No I only drained the system last weekend. The boiler has been playing up since we moved in in December.