6
Siemens
A6V12068497_en--_a
Smart Infrastructure
2021-04-16
Advanced functions
RDF270 fresh air unit controller provides different functionalities for equipment from basic
level with manual 3-speed fan to advanced level with ECM fan, internal / external circulation
and bypass function.
Internal / External air circulation
Some fresh air units have only single duct so they can be set to bring fresh air from outside
or circulate air via a built-in filter to maintain a good air quality.
There are also dual duct fresh air units to enable both internal and external air circulations.
Bypass function
This function is available in a dual duct fresh air unit and for external circulation only.
Without bypass function, the outside air is preheated or precooled by the exhaust air via a
built-in heat exchanging unit in the fresh air unit. Therefore, the outside air temperature can
be maintained in a similar level before entering the indoor area. The time required to heat up
or cool down the outside air by a heating or cooling equipment is much less since the tem-
perature deviation is small. As a result, it saves energy.
There are also other situations that require the bypass function.
For example, if the indoor area is too hot or cold while the outside temperature is cooler or
warmer, simply letting the outside temperature in to maintain a comfort level via the bypass
function (or no heat exchanging with exhaust air) is extremely useful and economical.
FAU-ECO function: (Eco-balance)
FAU-ECO is an automatic function to switch between internal and external air circulation and
therefore, P25 must be enabled or P25 = 1. In addition, to enable this function P02 must also
be set to 2, then select Eco Mode via Power button.
When FAU-ECO is selected, the RDF270 switches the air circulation between external and
internal as per the time ratio defined in parameter P26. For example, the factory setting (P26
= 1:5) means that within one hour, RDF270 stays in external air circulation for 10 minutes,
then switches to internal circulation for 50 minutes. The setting repeats as long as FAU-ECO
mode is active.
This function can help the users to maintain a balanced eco-system by controlling the
amount of fresh air inside the buildings or apartments to achieve good air quality for the liv-
ing space.
For related applications, see
15]
.
Error handling
TOUCH IC error
“Er4” is displayed upon internal TOUCH IC error.
Control parameters
Parameter settings
To optimize control performance, use the local HMI to enter parameter mode and adjust a
number of control parameters. All control parameter settings are retained after power down.
Proceed as follows to change the control parameters:
