Viessmann VITOCAL 300-G Technical Manual page 54

Design information
Required equipment
Pos. Description
Natural cooling function (NC)
Note
All required components (with a suitably designed plate heat exchanger) for the cooling circuit must be provided on site.
iQ Three-way diverter valve
iW Secondary cooling circuit pump
iE Contact humidistat
iR Primary cooling circuit pump
iT Mixer motor - three-way mixer
iZ Frost stat
iU
Extension kit for NC
iI Extension kit for heating circuit (cooling circuit) with mixer
iO Motorised two-way valve, normally closed
Cooling with an underfloor heating system
The underfloor heating system can be used for heating and for cooling
buildings and rooms.
3
Underfloor heating systems are integrated into the brine circuit via a
cooling heat exchanger. A mixer is required to match the cooling load
of the room to the outside temperature. Similar to a heating curve, the
cooling capacity can be matched exactly to the cooling load via a cool-
ing curve and the cooling circuit mixer that is regulated by the heat
pump control unit.
Surface temperature limits must be maintained to observe comfort cri-
teria and to prevent condensation. The surface temperature of the
underfloor heating system in cooling operation must not fall below
20 °C.
Install a natural cooling contact humidistat (for capturing the dew point)
in the underfloor heating system flow to prevent condensation forming
on the floor surface. This safely prevents the formation of condensate,
even if weather conditions change quite rapidly (e.g.during a thunder-
storm).
Estimating the cooling capacity of an underfloor heating system subject to floor covering and spacing between pipes (assumed flow
temperature approx. 14 °C, return temperature approx. 18 °C; Source: Velta)
Floor covering
Spacing
Cooling capacity with pipe diameter
–10 mm
–17 mm
–25 mm
Details accurate for:
Room temperature
Relative humidity
Dew point temperature 16 °C
Cooling with fan convectors Vitoclima 200-C (accessory)
■ Cooling operation possible either via separate cooling circuit or via
a heating/cooling circuit. For max. cooling capacity, select operating
mode "Fixed value".
■ Select an installation location where the heat pump can be easily
connected.
■ Consider the connection of the condensate drain to the domestic
drainage system or routing the condensate to the outside of the
building.
■ Power supply (1/N/PE,230 V/50 Hz) required.
■ When creating wall outlets, consider supports, lintels and sealing
elements (e.g. vapour barriers).
■ Only fit appliances to solid level walls.
VIESMANN
54
(cont.)
mm
W/m
W/m
W/m
25 °C
60 %
The underfloor heating systems should be sized in accordance with a
flow/return temperature pair of approx. 14/18 °C.
The following table can assist in estimating the possible cooling
capacity of an underfloor heating system.
In principle, the following applies:
The minimum flow temperature for cooling with an underfloor heating
system and the minimum surface temperature are subject to the pre-
vailing climatic conditions in the room (air temperature and relative
humidity). These must therefore also be taken into consideration dur-
ing the design phase.
Tiles
75 150
2 45 35
2 46 37
48 40
2
■ Never install appliances near heat sources or places subject to direct
solar irradiation.
■ Install appliances only in locations with good air circulation.
■ Ensure easy accessibility for service.
Output matching
The output of fan convectors can be modified. By changing the termi-
nal connections, 3 of the available 5 speeds can be assigned to the
three-stage speed selector of the fan convectors.
The heating and cooling capacities available with the respective
speeds are shown in the following table.
Carpet
300 75 150
23 31 26
25 32 27
28 33 29
VITOCAL 300-G
300
19
20
22