Lost connection rf on central wireless thermostsat

[Sandgoder]

Hello all, I have a central wireless thermostat controller which has lost connection to the base unit next to the boiler.

The reason for the loss of connection is that the wife has lent something on the base unit and it was touching the boiler on/off button which i beleive has reset it.

My question is how do i connect the wireless controller to the base unit. I know about holding in the button on hte base unit next to boiler but is there a combination to press on the wireless unit that puts it in a pairing mode.

Thanks

 

[Exedon]

Name or clear picture of thermostat/receiver please .
There are many different ones available!