how do I wire/controll ashp

[trig]

Hi
Looking for advice on the wiring controll set up for a 15kw ht ashp it is just running the central heating and not the dhw.
The unit is wired to a 6mm supply and needs a volt free signal from a room stat to controll it. This is fine but the stat needs to also trigger the circulation pump this would be OK but the stat has to be volt free so how do I power up the circulation pump on the heating side?
many thanks
Dave

[JonG]

You could use a relay, take a switched live from the stat to one side of the coil normally labeled A1 and a common neutral from the other side of the coil, A2.

You would then have a live supply to one side of one of the normally open contacts from the spur and then continue this to the pump from the other side of the NO contact.

The heat pump signal would then connect across another NO contact.

A good electrical supplier should sell you the kit you need if you confirm switching voltages which are negligible with a circulator.