you can install as many pumps as you like on a system, so long as its designed well, incorporating the correct valves, and pipe sizes, and switch controls.

if you go to an installation and find pipework, with more than 1 pump, with pumps fighting each other its because it has been badly designed or installed!!

done a couple of installations myself, where ive forgotten a NRV or AAV and as a result caused myself a return visit. dosnt feel good when you walk into your own plant room, commenting what a plonker ive been, if only i'd seen that before !!

havnt been any for years tho. must point out.

shaun