Expansion tank noises

I recently had more radiators installed, so the system was drained. Since that time, the noise of water being returned to the expansion tank in the loft has become excessive and can be heard from downstairs. The water re-enters the expansion tank at a fair rate of knots!!!! There are two tanks in the loft, so I assume that the smaller is the expansion for CH and HW and that the much larger one is the cold feed. I haven't had the CH on, so I don't know whether the prboblem is limited to just the HW. The boiler is a Potterton Netaheat. If parts are required, can they still be obtained?
Any help gratefully received - its driving me bonkers as it always seems to happen an hour before I get up! Oh for a good night's sleep!

the smaller tank is the feed and expansion for the ch and the larger will be for the hot water cylinder.

its either pumping over as a result of the alterations or the boiler is overheating for some reason.
have tyou asked the person who did the alterations to come back for a look?

parts are still available for the boiler.

and it needs fixing quickly. If you mean that water is gushing over into the F&E tank through the vent pipe that is curled over the top of it, it will be picking up dissolved air, and this will cause your radiators to rust away from the combination of water and air inside them.

Make sure your pump is turned to its lowest speed.

The corrosion sediment will also cause blockages in the pipes, will settle in your boiler and make it noisy, and will wear out the pump.

What colour is the water, and do you see a brown or black sediment in the F&E tank?

You need to buy a bottle of chemical cleaner, and a bottle of corrosion inhibitor, as well as getting the fault fixed. Sentinel and Fernox are good brands.

The water is clear and there is very little sediment in the smaller tank.
The water does come from a pipe that curls in over the top of it.

Should I maybe turn the boiler off completely and use the immersion for HW (CH is off anyway because of the weather)

This may be a daft question, but if the smaller tank is for CH and the larger for HW, why is water running into the smaller tank when only the HW is on???

the small tank feeds the circulating water that travels round the boiler, radiators, and the coil in the cylinder. So it runs between the boiler and the hot water cylinder when you have HW on. It is not "used up," the same water keeps circulating round.

If it is pumping over even when you are on HW with no CH, there may be a blockage, or the pump may be running too fast. It needs looking at by someone good. You may do well to ask around friends and neighbours for a recommendation.

If you can post digital photos of the pipework, pump and valves around the cylinder, boiler and tanks, someone may spot potential problems.

It would be a good idea to stop using the boiler until you get it sorted.

Thanks guys!!!