Operating and installation instructions
M-WRG-II P-T (-F, -FC), M-WRG-II E-T (-F, -FC) ventilation units
- 30 -
Meltem Wärmerückgewinnung GmbH & Co. KG
Am Hartholz 4 · D-82239 Alling
[email protected] · www.meltem.com
VENTILATION THE RIGHT WAY
V E N T I L A T I O N & H E A T R E C O V E R Y
9.3
Optional pushbutton for intensive ventilation
In addition to the three-step rotary switch, an optional pushbutton may be installed. This
allows you to start 15 minutes of intensive ventilation at maximum power level (100 m
3
/h).
The ventilation unit then resumes operation at the previously set ventilation level.
You can cancel intensive ventilation while it is running by selecting a ventilation level on
the three-step rotary switch.
9.4
Frost protection function
The ventilation unit is equipped with a frost protection function. In low outdoor tempera-
tures, the ventilation unit automatically switches to frost protection mode.
► Do not switch the ventilation unit off in the winter. Note section “6 Rules for correct
How it works:
The temperature on the exhaust air side is constantly monitored to prevent the heat
exchanger freezing. If the exhaust air temperature drops below -1.5 °C (-1.0 °C with
M-WRG-II E), the motor controller gradually changes the supply air and/or extract air
volume flow according to the set ventilation level so that the proportion of extract air is
increased. This causes the temperature to rise on the exhaust air side.
When an exhaust air temperature >5.5 °C (>7.0 °C with M-WRG-II E) is maintained for a
period of 3 minutes, the unit gradually switches back to the previous operating state.
If a value of >5.5 °C (>7.0 °C with M-WRG-II E) is not reached on the exhaust air side,
despite increasing the proportion of extract air within the unit’s control range (e.g.
because the room has cooled down), both the supply air fan and the exhaust air fan are
switched off.
After one hour, the unit resumes operation for 6 minutes and checks the exhaust air
temperature. If the measured exhaust air temperature exceeds a value of 5.5 °C (7.0 °C
with M-WRG-II E), ventilation mode starts with the previously set operating state.
If the measured exhaust air temperature is below a value of 5.5 °C (7.0 °C with
M-WRG-II E), the sequence described above is repeated.
Frost protection mode is ended when the exhaust air temperature is constantly above
5.5 °C (7.0 °C with M-WRG-II E) and the two fans are balanced.
In addition to monitoring of the exhaust air temperature, the speed of the exhaust air fan
is monitored continuously. When the exhaust air temperature has dropped to <2 °C, if the
speed increases significantly within a period of 2 hours, frost protection mode is activated
by the motor controller.
Any condensate is removed via the exhaust air pipe and condensate connection and with
M-WRG-II E units (with enthalpy) there is practically no condensation at all (if used for the
intended use, see section 2.5 on page 14, and in accordance with the rules for correct
usage, see section 6 on page 21, and if not exposed to excessive humidity).
