Bubbling noise in cylinder

[nigel purnell]

I have a vented system run by a potterton kingfisher boiler. When the hot water is switched on the you can hear the water being pumped around the system. after afew minutes there is a loud bubbling/ Gurgling noise coming from the Hot water cylinder near the feed from the boiler, that lasts for 10 secs then again after 30secs and continues on and off. The radiators have a lot of air i have bled them all but they fill up with air over night. I have checked the small tank which is full and no water is being vented back into this tank. Just before the gurgling you can hear a hissing sound that gets louder until the gurgling starts.
Where is all the air coming from and how do i stop the noise????

 

[TonyC]

Air can only get in to the system from the expansion/vent pipe. Sounds like there could be a blockage some where on the feed.

 

[Masood]

How sure are you that no water is being vented into the F&E tank? Have you looked at the vent whilst the gurgling noise is actually happening? I'm wondering if your coil has split...

 

[glenno1]

Call a local plumber or find 1 on here that is nearby that can help

 

[SafeGasInstall]

when you bleed your rads does the f and e tank refill its self or not ?

 

[nigel purnell]

Sorry for the delay ive been trying a few things. I have checked the pump OK, Vent Ok Seperator OK Feed OK
The bubbling noise is at 40c and sends hot water in a short burst into the small tank via the vent pipe and again after about a minute.?????When i turn down the hot water thermostat it stops and It doesnt do it when the diverter turns the central heating on???
How can i test the diverter and the cylinder coil ??

 

[dancinplumba]

It's your boiler kettling, it's scaled up/full of crud

 

[happyflyer]

Is the heating pump 3 stage

 

[SafeGasInstall]

time for a power flush and possible need for a new cylinder

 

[nigel purnell]

Is the heating pump 3 stage

Yes its been on setting 3 for the past 10 yrs . In reply to boiler being gunged up Ive washed it through No crud clear water???

 

[SafeGasInstall]

clear water could be indication of heat exchanger been scaled up after you washed it did you put inhibitor in the system ?
what is the state of the expansion tank ?

 

[dancinplumba]

Its an old cast iron heatex, believe me, it is rusted/scaled up. The waterways are reduced in diameter and cannot dissipate the heat quick enough and the water boils/kettles

 

[mountainman]

Boiler 'stat could be duff!