wiring a second heating pump?

I have a halstead combi boiler which runs my radiators. I have put in underfloor heating pipes to a pumped manifold and now need to wire the second pump can I do this by just wiring off the original boiler pump wire? I thought it may be a idea to put a 5amp spur to this to off set the load of two pumps firing together. is this the right way to go about this, Or any other ideas would be of help thanks dave.