4-Pipe Fan Coil Unit - Siemens RDG20 KN Series Basic Documentation

4
Functions
Control sequences

4.7.7 4-pipe fan coil unit

Heating and cooling
4-pipe application with
manual changeover
On/Off control
90 | 186
In 4-pipe applications, the thermostat controls 2 valves in heating and cooling
mode, heating/cooling mode by manual selection. Heating and cooling mode (P001
= 4) is factory-set.
The heating or cooling output can be released via operating mode button if P001 is
set to Manual (P001 = 3).
The diagrams below show the control sequence for On/Off control.
Heating and cooling mode (P001 = 4)
Heating mode with manual selection
(P001 = 3) or
energy saving (P010 = 2 & P014) in
heating sequence
T[°C] Room temperature
w Room temperature setpoint
X Dead zone (P055)
dz
Cooling mode with manual selection
(P001 = 3) or
energy saving (P010 = 2 & P015) in
cooling sequence
YH Control command "Valve"
(heating)
YC Control command "Valve"
(cooling)
SDH Switching differential "Heating"
(P051)
SDC Switching differential "Cooling"
(P053)
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