How to control second pump from Greenstar boiler?

[Nathan]

I've got a Worcester Greenstar 18i System boiler with integrated pump. The optional DT10RF controller has been installed. The boiler is used only for central heating.

I've also got a Wilo pump with three-way blender mixer connected to the underfloor hydronic pipes. The three-way keeps the hydronic loop at 45C whereas the boiler loop is more like 70C.

Currently the Wilo runs 24x7 from a socket on the wall. The boiler turns on and off as decided by the DT10RF thermostat. I'd like the Wilo pump to also turn off when the boiler turns off, but can't figure out how to do it.

The LP/NP terminals on the Greenstar seem to be disconnected; my multimeter shows 0V at all times. There are no LZ/NZ terminals like on the Greenstar 18i Regular model. I don't see any other switched lines from this boiler.

Is there a switched line somewhere I can use to control the Wilo pump?

 

[JohnKay]

Hi Nathan
Sorry to say I can't be of much help as I'm not familiar with your boiler. Having said that, I would not expect to find the Z terminals with the integrated pump. Have you not got terminals NS/LR ?
If so These could be used.
It looks like you may have to ask a registered engineer for more help.
There's one point I would make on the proposed set-up. If a fault develops on the external pump, causing a short, the overload current may damage the boiler.