Viessmann VITOCAL 151-A Installation And Service Instructions Manual page 40

Installation sequence
Connecting the secondary circuit
Contact humidistat
For area cooling systems (e.g. underfloor heating cir-
cuit, chilled ceiling), a 24 V contact humidistat
(accessories) is required.
■ Installation in the coolant flow of the room to be
cooled. If required, remove thermal insulation.
■ Electrical connection
Integrated heating/cooling circuit 1: Connection to
–
12-pole terminal at the bottom of the upper PCB
and upper luster terminal, terminals 1 and 2
■ If several rooms with different relative humidity levels
are part of the heating/cooling circuit, fit and connect
several contact humidistats in series:
Design the switching contacts as N/C contacts.
Operation without outdoor unit
The indoor unit can be operated without the outdoor
unit, e.g. for screed drying. In this instance, central
heating runs via the integrated instantaneous heating
water heater.
For this, the outdoor unit flow and return are hydrauli-
cally connected.
40
(cont.)
Fig. 31
Air vent valve
A
A