Optimum flow/return difference for Greenstar Ri

[jon92]

The radiators in my house have all been replaced over the last year or 2 and I'm wanting to balance them. My understanding is that first I should get the boiler flow/return temperature difference right with all the radiators full on, but I'm not sure what that difference should be. It's a Greenstar Ri, about 7 years old I think, I found a manual https://www.freeboilermanuals.com/worcester/ which gives heat output for '40/30', '50/30' and '80/60'. Does that mean I could set flow to 50 and return 30, for example? And if the difference is 20, should I also make that the difference on all the radiators to match when I balance them?
Thanks in advance for any help.

 

[muggles]

Yes, the difference should be 20°C, with a maximum return temperate of 52°C, but lower if possible

 

[jon92]

Thanks, and the radiators should have the same difference, is that right?

 

[muggles]

Yes, although you'll probably find that a 15ºC differential across the radiator gives you a 20ºC differential at the boiler due to losses in the pipework

 

[jon92]

Thank you again. I have set the pump to minimum speed, the flow is at 51 and the return is at 42 with all radiators fully on (but water off). I assume that as I adjust the difference at the radiators the boiler will naturally follow. Not a ten minute job is it.

 

[muggles]

No, it'll take you a few hours