Gas Ferolli 40/60 starting and then shutting off

[allyli]

The problem is -
The boiler starts and runs for around 1 minute and then shuts off again.
Then will not start again. It is a sealed system.

I have noticed that the pump upstairs beside the hot water cylinder does not start.

So what I did was bleed the radiator nearest the hot water cylinder.
I did this when the boiler was on and the pump then started and I was able to get heating however I did notice that the same radiator is constantly being filled with air and needed constant bleeding every few minutes. The pump is also making strange noises as if there is air in the pipes next to it and it is struggling to push the water around.
I also noticed that there was air that was in the pipes near the cylinder which I also bled out.

A friend suggested fitting an automatic air vent.
Will this solve my problem. The CH system has worked as is for the last 5 years, why would I need an AAV now?

Thanks,
Al

 

[twgas]

you say its a sealed system - so is there about 1 - 1.5bar pressure showing on the gauge?

 

[allyli]

Yes the pressure is currently at 1bar.

 

[twgas]

I think you may have a pump problem, but need to check a few things first.

does hot water work?

do you have the where-with-all to carry out electrical tests?

 

[allyli]

No the hot water does not work.
There is only 1 control valve beside the HW cylinder.
Looks like it is used for both the CH and HW.

When I turn on the boiler using the electronic timer there is a seperate button for HW or CH but pressing either one will switch on the CH and HW.

 

[twgas]

have you bled the pump, large screw in centre of pump.

set pump to highest speed (3 on most). turn on HW, does pump now run

do you have the where-with-all to carry out electrical tests?

 

[numpty1]

i take it it is a sigma,if so it could be a board fault,they are very poorly made and fall apart after a few years.failing that change the thermister/ntc.this one is gold in colour and different from the standard ferrolli thermisters.only do the above once you have proved the pump is u/s

 

[allyli]

Yes it is a sigma, I had the board and gas valve replaced a few months ago.

I bled the pump and it seems to be working fine but the radiator beside it keeps filling up with air.
And the next time I try and start the boiler again I have to bled again to start the pump.

I'm not sure how to carry out electrical tests.