Computherm Q4Z Operating Instructions Manual page 11

After connecting all the wires to the zone controller, mount its
rear panel on the wall with the screws provided.
In case of using an electro-thermal zone valve that operates
slowly and all the zones are closed when the boiler is inactive,
then the boiler should be started with a delay in order to
protect the pump of the boiler. This delay is activated in the
ON position of the jumper (black plug) "DELAY". (Under the
factory default settings this function is inactive.)
Replace the front cover of the device and secure it with the
screws at the bottom of the cover.
Connect the zone controller to the mains network.
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