Feed and expansion tank gurgling

[DBD34]

Our boiler feed and expansion tank has started to gurgle and drip at odd intervals. We just had a loft conversion done and the F&E tank is now easily accessible. It is in a small "plant room" (together with the Megaflow hot water storage tank) with a door, at the end of our loft conversion.

If the door is left open I can hear what's going on and it seems that when the boiler fires up in the morning that the water level drops very slightly and the ball cock allows a little water into the tank. Then it seems that when the boiler shuts down that there is a gurgle and a small quantity of water comes out of the expansion pipe and into the tank. The tank is not overflowing.

Did it always do this, just that I never heard it before, or is something amiss?

Thanks
Peter

 

[malko1974]

Pumping over is it cutting off on the boiler stat ? Try turning pump down

 

[45yearsagasman]

If there has been no alteration to your system then it's probably always done it. That is NOT pumping over and turning the pump down is poor advice without knowing more about your system.

 

[dilalio]

The F&E tank's water level should rise and fall during normal operation of the central heating.
As the water heats up it expands and contracts when cooling; and should ebb and flow through the bottom outlet of the cistern.
The volume of cold water should remain the same and not require the ball valve to operate, thus constantly topping up the levels - this would suggest a leak somewhere in the heating circuit.
The discharge from the vent pipe could be caused by a number of things and needs investigation on site to diagnose.
Look for leaks first and deal with that as your system water will, over time, lose its chemicals (inhibitor) and fresh water from the main will react with system components, leading to future problems.

 

[picasso]

There could be a small leak on the system but the gurgling is probably caused by a deadleg or excess air trapped in the rads.

 

[DBD34]

Thanks for the ideas. The tanks had to be moved to allow the new floor to be put in. There was no significant change to the pipework. The system was drained down and it is possible that there is still air in the system, which I guess might account for the ballcock dribbling as air is replaced by water? The situation with corrosion inhibitor is my main concern, so I'll keep an eye on things to see if it settles down

 

[Razor900]

A picture would help.

I presume the F+E is above the level of the megaflo??