I did not think about this much but my UFH manifold for the ASHP does not have flow gauges and looking at it does not look like there is a fitting for the manifold. From a bit of Googling it looks like a Robot low temp manifold, without a pump.  It's a Daikin Altherma 3 8Kw with the integrated tank. It seems to be running fine so I've not really questioned it. Flow rates are controlled by the unit. 

 

Any thoughts?

 

 

I would use auto balancing actuators on that set up and be done with it 

I think I might have boxes of them in the garage.