User Manual

Functions
Control sequences
4
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4.7.7.1 4-pipe application with PICV and 6-port control ball valve
as changeover (RDG260KN)
On a 4-pipe fan coil application with DC 0...10 V fan control, the RDG260KN
controls a combi valve (PICV) in combination with a 6-port ball valve as
changeover.
Note: Set DIP# 1 & 4 to ON (4-pipe with 6-port ball valve as changeover and
PICV).
This application is used on 4-pipe systems with one heat exchanger and differential
pressure controller (using a PICV).
The changeover signal DC 0…10 V controls the flow rate on the combi valve
(PICV), while the 6-port ball valve, connected to the relay outputs, is used as the
changeover to switch the sequence between heating and cooling.
Enable the flow limitation function (for PICV) via parameter P256 to balance
heating and cooling systems and avoid hydraulic problems caused by the different
flow rates. (see Additional functions [➙ 41]).
The fan can only be set on DC Y50 output on this application.
Set fan operation (P350) to enable (enable by default).
T[℃] Room temperature Y10 DC 0…10 V signal
W Room temperature setpoint YH
Control command "Valve"
(heating)
YC
Control command "Valve"
(cooling)
P256
Flow limitation function for
heating only
See Chilled/heated ceiling with Pressure Independent Combi Valve and a 6-port
ball valve as changeover (RDG260KN) [➙ 71] for detailed information on how the
thermostat limits the mix of the heating and cooling medium as well as on control
outputs.
The connection diagram for application 4-pipe with PICV and 6-port ball valve as
changeover is available in Connection diagrams [➙ 126].
Principle