Potterton Profile 60 wont run for long!

[Hughsy]

My Potterton Profile 60 wont run following draining the system down. Its a sealed system with a Megalflow.

I had a leak from a valve, therefore i drained the system down using a long hose pipe into the garden. Repaired the leak and filled the system back up again.
Following this, the bolier pilot and main burner lights for about 3 or 4 minutes but then cuts out, I then have to wait approx 10 mins to try again but the same thing keeps happening. I have bled the rads, pump and air valves near the Megaflow. I have tried running only Hot Water or Heating but the same thing keeps happening.

Any suggestions welcome please

 

[twgas]

presume its an open system, check cold feed for blockages

if sealed add some more water (1bar) on gauge

 

[Hughsy]

presume its an open system, check cold feed for blockages

if sealed add some more water (1bar) on gauge

Thanks for your prompt response Mick, its a closed system and has 1.5 bar at present anyway...

 

[twgas]

next thing is to check pump is working.
undo screw on end and check, with small flat bladed screwdriver, its spinning

 

[Hughsy]

next thing is to check pump is working.
undo screw on end and check, with small flat bladed screwdriver, its spinning

The "Grundfos Selectric" doesnt appear to have screw on end, it has disc about the size of a 2p coin which when turned drips very hot water so reluctant to completey undo, also there is 230v there all the time, even when boiler has tripped - is this correct ? Cant see where it should be spinning? Sorry to be so dumb!

 

[twgas]

if the heat scares you let it cool down first. if its the water put a couple of old towels down

 

[GasMan1965]

Put a long screwdriver on the pump and the other end in your ear so acts like a stethoscope then change pump speed and you should hear it change tone,, if it just hums then its probably stuck .. do as twgas says and remove screw with a small bowl to catch drips or old towels as it will be a bit black ..

 

[GasMan1965]

If pump is stuck then the heat wont get past the pump as such so it will be hitting a dead end and boiler over heats ..

 

[Hughsy]

Many thanks for your replies

Okay, so I have removed the screw (I expected it burst with water under pressure - durgh!), done the screwdriver trick which only changes a hum slightly and I cant see or feel it spinning. Its hot on one side and cool on the other so i guess this is the fault...

Is it straight forward for a novice like me to replace or should I call in the pro?

Also what are the valves either side of the pump for?

 

[GasMan1965]

Wont the screw driver start it off again?

They are the isolation valves for changing the pump but take note that they often dont shut off fully so let water by when you remove the pump ,, also assuming you can undo the big nut ..

 

[twgas]

try spinning shaft with screwdriver, may take a few attempts if its well seized. If it does go should be alright for a while but would be worth getting in a new pump for when it happens again.