double pumping

[UKenGB]

I want to be able to independently pump both the DHW and the HTG circuits. If I use motorised zone valves with end switches, it looks like either both pumps come on every time the boiler is activated OR the pumps start as the valves BEGIN to turn rather than only when they get to fully OPEN OR additional control systems are required. Or does anyone have any ideas how to best control 2 pumps (and single boiler) and avoid these issues?

What about the Grundfos Pump Plan? I believe this uses mechanical valves to prevent unwanted flow, but how does it keep the pumps independent when only 1 boiler feed is used. Does the Pump Plan incorporate some additional electronics to cope with this? Anyone know about the Pump Plan? Any wiring diagrams available to view/download?

Thanks.

 

[stevetheplumber]

its normal to fire pumps from a motorised valve using the aux circuit the valve doesnt switch the aux circuit until its partially open

just thought more about this you may have to wire at least one pump to the boiler as it may need pump over run in this case you can incorperate a bypass in to that circuit

 

[Mike Jackson]

The grundfos pump plan used a proprietary wiring centre that incorporated relays. I'm not sure it's available any more.

To control two pumps and one boiler you need to use relays.

Mike