Flow rate keeps dropping

[jayc89]

If I shut all the other flow gauges off and just open that loop it’s making almost a scratching noise, possibly air flowing through it?

[PeterW]

38 minutes ago, jayc89 said:

If I shut all the other flow gauges off and just open that loop it’s making almost a scratching noise, possibly air flowing through it?

yep / open it right up and also turn the pump up 

[jayc89]

6 minutes ago, PeterW said:

yep / open it right up and also turn the pump up 

 

How long should that take? That's what I did, for about 10 minutes, and the volume of air in the gauge didn't noticeably reduce. Loop is approx 58m in length/7 litres in water volume. 

[jayc89]

Got around to tackling this over the weekend. Started by closing off all loops, hooking up a hose pipe to the return, opening the problematic loop and turning on the fill loop near the boiler. A few air bubbles came out, but not loads. Turned the heating back on and had the exact same problems. Flow gauge bouncing around, half empty and eventually the flow rate dropping off. So I went full throttle. Hooked the hose pipe on to the flow and a bucket onto the return and massive amounts of air was forced out. It must have taken 6-7 buckets before the bubbles stopped - all the while the AAV was also releasing some. Seems to have done the trick though, the flow gauge is full with water, like the others now and flow rates remain stable. Won't be using that plumber again...