Natural Cooling Function; Function Description - Viessmann VITOCAL 222-G Technical Manual

Design information
Selection: 1 Vitocell 100-E with 750 litre cylinder capacity.

11.11 Natural cooling function

Function description

With natural cooling, the heat pump control unit regulates the following
functions:
■ Switching all necessary circulation pumps, diverter valves and mix-
ers
■ Recording all essential temperatures
■ Dew point monitoring
The control unit enables the natural cooling function if the outside tem-
perature exceeds the cooling limit (adjustable). Control operated in
weather-compensated mode when cooling via heating circuit (under-
floor heating circuit). When a separate cooling circuit is used, e.g. a
fan convector, then the control is room temperature-dependent.
NC-Box
■ The installation room must be dry and free from the risk of frost.
■ Vitocal 200-G/300-G: Install the NC-Box inside the installation room
above the heat pump and connect with the corrugated pipes sup-
plied.
■ Compact heat pumps: Install the NC-Box near the compact heat
pump and use on-site pipes for the hydraulic connection.
■ Carry out the diffusion-proof thermal insulation of all brine and cold
11
water lines in accordance with standard practice to prevent conden-
sation.
Natural cooling with the NC-Box
Subject to the probe/collector system and the temperatures under
ground, the NC-Box can transfer a refrigerating capacity of up to
5 kW.
For cooling, it is possible to connect either a heating/cooling circuit,
e.g. underfloor heating circuit or a separate cooling circuit, e.g. a fan
convector.
The NC-Box is equipped with all necessary circulation pumps, diverter
valves, mixer and sensors as well as the essential KM BUS interface
to the heat pump control unit.
The heat that is extracted from the heating/cooling circuit is transferred
to the ground by the NC-Box. This heat exchanger is connected in
series and enables a system separation between the primary and the
heating circuit.
Note
Thermally insulate all lines on site with vapour diffusion-proof mate-
rial.
Arrangement of the NC-Box adjacent to the heat pump
■ For compact heat pumps Vitocal 222-G/242-G/333-G/343-G.
■ With the Vitocal 200-G/300-G, if the installation room above the heat
pump is not high enough.
■ Hydraulic connection with on-site pipes.
Arrangement of the NC-Box above the heat pump
■ With the Vitocal 200-G/300-G.
■ Hydraulic connection with corrugated pipe set.
VIESMANN
66
(cont.)
DHW heating by the heat pump is possible during the cooling opera-
tion.
Note
■ For cooling operation via a separate cooling circuit, a room temper-
ature sensor must be installed and enabled.
■ For cooling operation via a separate cooling circuit or heating circuit
without mixer, use a contact temperature sensor to capture the flow
temperature.
■ Power supply (1/N/PE, 230 V/50 Hz) is required.
Recommendation: Utilise the heat pump power supply from an on-
site power distribution board.
■ If the NC-Box is used with a separate cooling circuit (exclusively
used for cooling), protect that circuit via an additional expansion
vessel and safety valve.
■ Use only Teflon and EPDM seals for the connections on the NC-Box.
D E
C
B
A
A Heat pump
B Primary circuit return (heat pump brine outlet)
C Flow, primary circuit (brine inlet, NC-Box)
D Return, heating/cooling circuit or separate cooling circuit
F
G
H
K
VITOCAL