Boiler/CH Settings ??

[Aletank]

I live in a 3 bed detached 5 year old house with Conventional Heating with 9 Single Panel Finned Radiators.
I use to have the CH pump on Speed 3, The Boiler on Full(6), The Water Temp on my cylinder on 60C. and all worked fine.
I've just replaced the CH Pump and thought I'd try it on Speed 1, all the Rads heat up just the same etc so I' thought I'll leave it on this. I've noticed my Bolier sounds like its bubbling now though, so I've turned that down to 5.
What do you think I could turn the boiler setting down to without noticing a difference in radiator temprature ?
what settings do you think i should have it all set on ?

 

[oilman]

Traditional temperature for boiler flow is 82 deg C, return is 71 deg C. Set the boiler to 82, open all radiators get system hot and then adjust the pump speed to give nearest to 71 deg C on the return. Job done.

 

[Aletank]

Would that mean getting Radiator Thermometers for the Flow & Return pipes ?
My boiler only has 1-6 settings

 

[oilman]

Yes.

Use a thermometer to measure the flow temp at the boiler, then you know what it is.