11
Defrosting of heat recovery rotor
The purpose of the defrosting function is to prevent the frosting/freezing of the heat recovery rotor in extremely
cold weather. Prevention of frosting of the heat recovery rotor control is done on the temperature basis.
Defrosting of heat recovery rotor will be switched in extremely cold weather when the temperature of exhaust
air declines relatively low. The supply air fan speed slows down distinctly after the function has been
activated; speed of the exhaust fan will remain unchanged. Air pressure in the apartment will decline while
the defrosting of heat recovery rotor function is switched on. Maximum operating time and minimum time
between cycles can be defined for this function. In extremely cold weather, if the temperature of the exhaust
air is still declining despite activating of the defrosting function, the supply air fan will automatically get
switched off and the exhaust air fan will be switched to the minimum speed. When the defrosting function
is active, the text " Defrosting" appears on the display and the fan speeds can not be changed. Also the
Fireplace function can not be switched on.
Attention!
If the Fireplace function is used at extremely cold weather, the temperature of the exhaust air
may declines distinctly and this may switch on the defrosting function immediately after the fireplace mode
is turned off and the HRV has returned to its normal mode. However, if the Fireplace function is activated,
the defrosting function cannot be activated.
2.3 Accessories
HRV can be controlled with the following external transmitters and switches supplied as an extra equipment.
CO
2
Control
The device can be controlled based on the external CO
2
transmitter data as follows:
When the CO2 concentration is within limits, the unit operates at its normal speed.
When the CO2 concentration value declines below the lower limit, the unit operates at the
speed ”Unoccupied”.
When the CO2 concentration value raises over the upper limit, the unit operates at the "Boost" speed.
Humidity boost
The unit can be controlled based of the external humidity transmitter data as follows:
When the humidity raises above the set minimum limit, the unit operates at the "Boost" speed.
Forced boost
The Forced boost operates as follows if the "Forced boost" function is chosen through the “Input E7 Mode”
item of in the maintenance menu.
when the input E7 is closed, the fans will operate at the “Boost” speed;
when the input E7 is open, the speed of the fans will return to the speed of the highest priority.
Forced pressure increase
The forced pressure increase operates as in the following way, if the "Forced boost" function is chosen
through the “Input E7 Mode” item of the maintenance menu:
When the input E7 is closed:
the input fan speed is set to the normal speed
the exhaust speed is set to the minimum speed
