constant air pockets

[bruce 1411]

I have a bog standard indirect gravity and pump fed system with no 3 port or motorised valve i:e c.h has priority.

I'm constantly getting air locks which stop the water in the cylinder from heating. so no domestic hot water.

I've taken air locks out of the nearest and furthest rad pipes (8mm) and from the boiler return to the cylinder. I've also vented the rad in the same room as the cylinder about once a month and let about a pint of water in but theres no sign of a leak at the rad or under the floor but they keep coming back.

The feed gets red hot in seconds and the return is less than tepid but when i crack the nut on the T i get water not air its doing my head in im sick of draining and refilling it.

Any ideas greatly appreciated

 

[Softus]

Is there any water in the F&E cistern?

 

[bruce 1411]

sorry, my fault im not a good explainer, when i said no domestic hot water i meant there is water its just not heating, it takes 4 hours with the gas on full bore to get it anywhere near hot enough for a bath etc, yes the f&e tanks are full

 

[cjb1971]

Is the f+e pipe blocked?sounds like your system may be low on water

 

[Softus]

Can you identify the pipe going into the cylinder coil?

When the boiler is on, this pipe should be very hot. Is it?

Do you have any motorised valves?

 

[bruce 1411]

thanks guys i've sorted it. i cracked the return T but all i got was water because it was fed from the loft then i occured to me that the lock might be in the coil rather than the pipes so i cracked the feed T (blindingly obvious) im an idiot sometimes and the head of water pushed the lock out 30 mins later extremely hot water, im so happy. thanks again