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AB Industrietechnik srl – Via Julius Durst, 70 – 39042 BRESSANONE (BZ) Italy – Tel: +39 0472/830626 – [email protected] – www.industrietechnik.it
24. Heat exchanger
If a significant quantity of fresh air is needed, the air handling units are equipped with heat exchangers to enable energy sav
-
ing. The heat extracted from return air is transmitted to supply air in order to pre-heat or pre-cool it and save energy.
If there is a cooling or a heating request and conditions for recovery are present regulation is first done using the heat ex
-
changer and then on the cooling or heating battery, if present.
The regulator can control most types of heat exchanger
and by parameter
012,
the selection can be done:
For cross-flow heat exchanger set
012
=1.
For double battery heat exchanger set
012
=2.
For on/off rotary heat exchanger set
012
=3.
For modulating rotary heat exchanger set
012
=4.
For no heat exchanger set
012
=0.
• Conditions for recovery:
The heat exchanger (excluded cross-flow heat exchanger) is not always active, it is activated in heating if there is a heating
request and if the following condition of activation in heating is verified:
ON
OFF
Ext - Ret
182
181
184
183
Diff
182
181
ON
OFF
Ret - Ext
182
181
Ret = return temperature
Ext = external temperature
181
:
setpoint of heat exchanger
182
:
differential of heat exchanger
If Ret - Ext > heat exchanger setpoint
181
, the heat exchanger is authorized to run if necessary.
If Ret - Ext <= (heat exchanger setpoint
181
- heat exchanger differential
182
) the heat exchanger is not authorized to run.
it is activated in cooling if there is a cooling request and if the following condition of activation in cooling is verified:
ON
OFF
Ext - Ret
182
181
184
183
Diff
182
181
ON
OFF
Ret - Ext
182
181
Ret = Temperatura di ripresa
Ext = Temperatura esterna
181
:
setpoint del recuperatore
182
:
differenziale del recuperatore
If Ext - Ret > heat exchanger setpoint
181
, the heat exchanger is authorized to run if necessary.
If Ext - Ret <= (heat exchanger setpoint
181
- heat exchanger differential
182
) the heat exchanger is not authorized to run.