How to control second pump from Worcester Greenstar boiler?

[nhand42]

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?

 

[Megavolt]

The pump needs controlling by a prog room stat or timer for the room the UFH is supplying. Ideally via a zone valve to provent feed back

 

[nhand42]

Ok, but the DT10RF is already a prog room stat. With a second prog room stat for the pump they're going to fight each other. The DT10RF might decide to turn the boiler on while the second room stat decides to turn the pump off. That's not a good outcome.

I'd like to use only the DT10RF prog room stat - which already controls the boiler and it's integrated pump - to also control the UFH pump.

 

[davesparks]

I don't think it is going to be possible, but your best bet may be to give Worcester Bosch a call and see what they say.

The DT10RF is integrated into the boiler front panel and plugs straight in to the internal control electronics. It doesn't come out to a set of external connections.

 

[guest119]

Cant you just put the 2 pumps in parallel?
IE dip into the multi plug or whatever is the final connection to the integral pump.

Boydy

 

[Mr Brady]

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

How about clamping a stat to the boiler flow somewhere near the underfloor heating manifold, then the water temperature can act as your "switched line".

 

[Megavolt]

Why not get rid of the Dt10rf, will make life easier

 

[wozz]

The internal controls disable the connections for external controls. If you change to external controls remember to order the blank plate for the boiler if you don't have the existing one.

 

[Worcester]

nhand42, I guess you didn't like the honest answers and great comprehensive advice that you got on the Plumbers forum so came here for a 2nd opinion

The answers are over there