After diverter valve replacement - boiler cuts out.

[lonspwi]

I have just had a 3 way diverter valve replaced which needed a drain down of the system.
After the work had been done and system had been refilled, and boiler relit, the boiler cuts out after about 5 mins of heating and I have to press the reset button after it has cooled down.
The boiler is a Potterton Prima 30F.
The system has been drained down twice now and refilled from the bottom up, i.e connecting up the drain to the mains water. The boiler now stays on a bit longer and the pipes are getting hot, even to the point of one of the rads, however the problem still persists - the boiler cuts out after about 5-10 mins. Can anyone suggest what to do next ?
Thanks in advance.

 

[kevplumb]

did you manually open the valve on refilling

did you vent the cylinder (usually a brass screw at the side )

 

[ollski]

bleed the rads and the system

 

[kevplumb]

 

[lonspwi]

The valve was in the mid position i.e feeding both cental heating and cylinder. There is a small bleed valve on the pipe going into the cylinder, and this was vented as were all the rads. I've vented everything I could find a vent for. Do you think there is some blockage in the cold feed other than air ? Maybe a flushing product should be used ?

 

[ollski]

vent it again and do the pump aswell....boiler is cutting out on overheat because the water isn't circulating. Try to keep starting the pump for a second or two to release any air then bleed it out.

 

[kevplumb]

is the valve in the right way ie B is hot water

 

[lonspwi]

Yep, "B" is pointing toward the cylinder. I have also bled the pump a few times, although only water was coming out.

 

[ollski]

when you vent it next time just make sure it is actually spinning, you will see it when you take the big nut out of the centre of the pump

 

[lonspwi]

The pump is making a noise and sounds like it is pumping water, it's getting a little hot though.

 

[kevplumb]

undo the big screw and see if the shaft is actually turning

id go with ollski on this its down to curculation