One zone in UFH cold on return - could I try faster flow rate?

[Siggles]

I have one zone that has felt cold on the return pipe (and that piece of pipe is the only one that isnt the same colour as the others - ie, isnt blue - from the inhibitor). That room has not been heating well.

 

I saw a few air bubbles moving round so feel it must be trapped air. I increased the flow rate on the flow meter to 5L and lots more bubbles shot round. Suddenly the return pipe now feels hot. Could that be enough to remove the trapped air do you think?

[Conor]

Do you have an air release valve on the system? If there was air in that loop, has to go somewhere.

 

Re flow rate, 5lps is huge. Refer back to the design sheets and take it from there 

[JohnMo]

If there is air in the loop, you need to push it out with a main water hose pipe, otherwise it just moves about and never really gets pushed out.

[sharpener]

Might not be trapped air. On my UFH the flow regulators are very susceptible to blocking with crud. Opening the regulator and closing all the others on the manifold usually shifts it. The bubbles might just be incidental. Do you have any filters, or air release valves?