Functions; Internal Pre-Heater; Heat Exchanger Frost-Protection - Helios EC green Vent KWL EC 700 D Pro / WW Notice De Montage Et D'entretien

Installation and Operating Instructions
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IMPORTANT NOTE
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NOTE
Central ventilation units KWL EC.. D Pro/WW
3.2

Functions

3.2.1 Internal pre-heater

According to criteria for passive houses, a pre-heater is mandatory to prevent the Cross counter flow heat exchanger
from freezing! The pre-heater is located behind the outside air filter F7.
– Detailed pre-heater regulation:
The pre-heater is active if the following conditions are met:
Condition I: Outside air temperature (sensor EXT1) lower than -4 °C
Condition II: Outgoing air temperature (sensor INT2) lower than +0 °C
Condition III: Pre-heater is not deactivated in menu section (12 Pre-heater)
If all conditions are met, the pre-heater will be controlled corresponding to the difference to achieve a constant outgo-
ing air temperature.
The pre-heater is deactivated if the following conditions are met:
Condition I: Outside air temperature (sensor EXT1) higher than -3 °C
or
Condition II: Outgoing air temperature (sensor INT2) higher than +4 °C
Important note:
The pre-heater only activates if the supply air ventilator is extracting the minimum flow rate and there are no errors. If
the KWL unit is switched to standby mode, the supply air ventilator will run for 60 seconds in case the pre-heater was
activated before that. If the pre-heater before this and, for example, the KWL unit is switched to standby 20 seconds
later, the supply air ventilator will then only run for 40 seconds.
General information on the pre-heater
The pre-heater is equipped with two safety temperature limiters, the STL (auto reset = trigger temperature +50 °C) and
(manual reset = trigger temperature +120 °C) are connected in series. Once a safety temperature limiter is triggered, the
preheater will be disconnected from the power supply and an error will be displayed on the controller.

3.2.2 Heat exchanger frost-protection

The heat exchanger frost-protection function is divided into 3 steps:
Step I: Activation of pre-heater (see section 3.1.1)
Step II: Reducing the flow rate / Outgoing and supply air fan
Condition I: Pre-heater has been switched on for longer than 3 minutes
Condition II: Outgoing air temperature (sensor INT2) lower than 0 °C
If both conditions are met, the outgoing and supply air fan will reduce. The pre-heater will not be deactivated in this
period.
Step III: Emergency shutdown Supply air fan
Condition I: The flow rate of the outgoing and supply air fan is reduced for longer than 5 minutes
or
Condition II: The pre-heater is deactivated.
AND
Condition III: Outgoing air temperature (sensor INT2) lower than 0 °C
If the conditions are met, the pre-heater will be deactivated and the supply air fan will be shut down.
The Heat exchanger frost-protection is deactivated if the following conditions are met:
Condition I: Outside air temperature (sensor EXT1) higher than -3 °C
or
Condition II: Outgoing air temperature (sensor INT2) higher than +4 °C
If the conditions are met, the heat exchanger frost-protection will be deactivated.
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