Air in radiator and water in overflow pipe

Hello,

Ok, I have two problems which I think might be connected:

1) We had a bathroom radiator moved about a metre along a wall about 10 months ago. Since then im constantly bleeding the radiator approx every three to four weeks and getting a fair bit of air coming out. I've tried the hydrogen test to see if it is air or gas and I can't get the gas to light so it must be just air.

2) I've just been in the loft and noticed water has been dripping from one of the joints on the expansion pipe which runs to the outside of the house. The cold water and expansion tank both join to the expansion pipe. The pipe rests on a joist and it looks like it has been more than a few drips has escaped from the faulty joint.
I looked inside the header tank and the level is below the overflow pipe. In the cold water tank the ball float was slowly dripping (but the bath has just used, so the tank had just been refilled) I did notice there was about 2" of limescale & watermarks above the current water level.

Is there anything I can do to determine if it is the header tank or the cold water tank which is causing water to get into the overflow pipe and also filling my radiator with air?

Thanks for any advice or guidance before I call a plumber out,

Glyn

Is the level of the scaling and watermark right at the bottom of the overflow outlet from the Cold Water Cistern?

Air getting into your rad is a different issue. Leaky connection sounds like a potential cause if that rad has recently been moved and the one that needs bled all the time

I didn't check to see if the water mark was in-line with the over-flow pipe, I will check that when I go back in the loft tomorrow night.