Computherm Q4Z Operating Instructions Manual page 6

connection point is suitable to control the heating in such
rooms (e.g. the hall or the bathroom), which do not have
a separate thermostat, do not need heating at all times
but need heating when any of the four zones heat. This
connection point is also suitable for controlling a central
circulating pump, which starts whenever any of the heating
zones starts. When the delayed start of the boiler function is
activated (see the next paragraph), the delay is applicable for
the Z1-4 connection point too.
The first, second, third and fourth zones also have a joint
potential-free connection point that controls the boiler (NO
and COM). These connection points clamp shut following
the heating command of any of the four thermostats, and
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