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ABB i-bus KNX
3.2.3.3
HVAC system –
2 Control value/2-pipe
© 2010 ABB STOTZ-KONTAKT GmbH
Commissioning
If option 2 Control values/2-pipe is selected, additional parameters appear:
Toggle via automatically
Valve COOLING not usable
This parameter serves as a note or remark.
Valve HEATING/Valve COOLING
Toggling between HEATING and COOLING is implemented by
updating the control values. The HEATING/COOLING status is then
set accordingly.
Note
The switchover between HEATING/COOLING should occur
exclusively in the respective thermostat. Here only HEATING or
COOLING is always active depending on the last control value
received.
- If a control with a value > 0 is received, the fan and the
corresponding valve are controlled.
- The other valve is closed.
- If a control value with a value = 0 is received, this is ignored if the
other control value > 0.
Caution
With a 2-pipe HVAC system both the Control value HEATING
as well as the Control value COOLING act on the heating valve
(electronic outputs O, P). Please note that always the last control
value received controls the heating valve.
For 2-pipe systems only the communication objects for the
HEATING valve are relevant.
The communication objects in conjunction with the COOLING
valve, e.g. status, forced operation or valve purge are not effective.
For further information see:
page 124
Operation HEAT/COOL after
bus voltage recovery
Options:
unchanged
HEATING
COOLING
Using this parameter the reaction after bus voltage recovery is set.
unchanged: After bus voltage recovery the state which existed before
bus voltage failure is set.
HEATING: After bus voltage recovery the HEATING state is set.
COOLING: After bus voltage recovery the COOLING state is set.
Design of a HVAC system with Fan Coil
Units,
31
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