My rads wernt heating up. I checked for air lock and balanced. Quarter turn upstairs and all open down on lock shield. Central heating pump wilo gold 50 was noisy. I took a wild guess the pump wasn't circulating well. Purchased a wilo yonos which I was told is the direct replacement. Installed fine and flow arrow pointing down, same as the old one. Set the level to 3 speed. Rads all heating up, still not perfect but 90% better, they are old rads as is the boiler so hoping to keep the system going until I upgrade. some rads are hot bit not as hot as others. I then heard a water dripping sound from the loft. Looking in the loft there is what I believe to be an expansion pipe with water coming out into a smaller tank. Turning the pump to 1 stops the water. It's a 5 bed house so thought a faster speed was needed, not sure if the pump is too efficient and 1 is ok or if there is a bigger issue being masked?