![background image](http://html.mh-extra.com/html/carrier/39hxc/39hxc_manual_2561930021.webp)
Air intake fan
104
Air intake ventilation control
Air intake fan
105
Air extraction ventilation control
106
Multiplication factor value of the signal sent by the air extraction fan with pressure control in the supply air
duct
3.8 - Energy recovery
3.8.1 - Recovery operation
The unit has a variable speed rotary heat exchanger or a plate heat exchanger. This is used to heat fresh air in winter or cool fresh air
in summer.
Energy recovery (rotary heat exchanger started up or plate heat exchanger bypass closed) starts under the following conditions:
-
If the heat recovery unit heating requirement is greater than 0% and the return air temperature is higher than the fresh air
tempe difference P225
-
If the heat recovery unit cooling requirement is greater than 0% and the return air temperature is lower than the fresh air temperature
- difference P225
-
During the ventilation start-up phase
If there is a free cooling or night cooling requirement, the recovery is stopped. There are temperature hystereses to prevent inadvertent
starts/shutdowns.
The rotary heat exchanger can be forced to shut down using parameter P158 (accessible via BMS)
158
load shedding of rotary heat exchanger
225
Temperature difference for heat recovery unit run authorisation
Temperature
Return
< fresh air –P225
Return air
> fresh air + P225
Heat recovery unit
requirement
Cooling > 0%
On
Off
None
Off
Off
Heating > 0%
Off
On
Free cooling Night cooling
Off
Off
3.8.2 - Heat recovery defrost
Heat recovery unit frosting is monitored as standard via the fresh air temperature, or optionally using a differential pressure sensor
(P37).
37
Differential pressure sensor on the heat recovery unit
With preheating coil
There may be an electric heater to prevent frosting of the heat recovery unit.
If there is a pressure sensor, a 5-minute preheating cycle is activated once the pressure difference on the heat recovery unit is above
the threshold (P328).
Otherwise, monitoring is carried out via the fresh air temperature sensor. In this case a one-hour preheating cycle is activated once
the fresh air temperature drops below the threshold (P227).
31
Electric pre-heater
220
Heat recovery unit min. flow rate pressure drop threshold
221
Heat recovery unit max. flow rate pressure drop threshold
227
Heat recovery unit frost protection temperature threshold
328
Heat recovery unit pressure drop calculated threshold
Without preheating coil
In the absence of a preheating coil or if the coil is unavailable (faulty or load shed), the heat recovery unit bypass is opened 80% (for
a cycle 10-minute cycle), or the rotary heat exchanger (for a 5-minute cycle) set to minimum speed, once the pressure difference on
the heat recovery unit is above the threshold (P328) or the fresh air temperature is below the threshold (P227).
226
Gradual speed heat recovery unit min. speed
3 - FEATURES
21
Summary of Contents for 39HXC
Page 1: ...C O N T R O L S M A N U A L Translation of the original document 39HXC 39HXE 39HXV ...
Page 2: ...2 ...
Page 62: ...62 ...
Page 63: ...63 ...