What size Central Heating Pump Do I Need?

[scraggy55]

I need to buy a new Pump for my Central Heating System. I am running a 28 watt Boiler and I have 8 Radiators. I have recently installed a Vaillant Ecotech Plus 428 28 Kw Boiler.

[buildersmate]

You must have noticed a difference, changing from a 28W boiler to a 28kW boiler! (but I know what you mean).
Unless you changed the pipework / rads as well, there is no particular reason to change the pump as well. If you are determined to do it, fit one of a higher rating - you can always switch it down a notch.
Personally I don't reckon it is worth messing with second-rate pump manufacturers and believe Grundfos to be the best, and I'd fit an Alpha2, which adjusts itself automatically to the load demanded by the water resistance.