Shower Pump 22mm fitting to existing 15mm pipework

[lightbeing]

Hi,
I am replacing my current twin shower pump with a Monsoon 2.0 bar twin pump, my current installation has 15mm dedicated pipes to the pump and from the pump to the shower mixer. The Monsoon pump has 22m fittings, can I get away with it by fitting 22mm to 15mm reducers on the shower pump side. Will this represents a problem (pump load, etc.) ? I did phone Stuart Turner Tech line to check and the guy insisted on having 22mm pipework all over! without giving real explanation, Can I not keep my existing 15mm pipework?

Thanks for your help.

 

[ajrobb]

This is a 15mm 2.0 bar twin impeller pump
http://www.plumbworld.co.uk/stuart-turner-showermate-20-1655-18625

 

[lightbeing]

I have already bought the Monsoon 2.0 (second-hand in excellent condition), it looks like this:
http://www.taps4less.com/PP/E-ST46343.html , my question is whether it can be connected to 15mm pipework?