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User Manual
HRU-PremAIR
6.5 By-pass
6.5.1 Passive Heating
Passive Heating can be used to heat a building with outdoor air when the room temperature is lower than the
outside temperature and lower than the temp setpoint.
For example, in the spring, after a cool night, a cooled down building may be heated by outdoor air, which
has been heated by the sun throughout the day.
Passive heating may also be referred to as ‚Free heating’, as no conventional energy consumption needed.
Heating is possible when all of the following conditions are met:
• The outdoor temperature ≥ the extract temperature (room temperature) + 5˚C (Free ventilation outside
offset #118).
Heating is not possible when one of the following conditions is met:
• The outdoor temperature ≤ the extract temperature (room temperature) + 5˚C
(Free ventilation outside offset #118 -0,5˚C).
Heating is activated when all of the following conditions are met:
• Heating is possible.
• The extract temperature (room temperature) ≤ +20˚C (Free ventilation heating setpoint #117).
Heating is deactivated when one of the following conditions is met:
• Heating is not possible.
• The extract temperature (room temperature) ≥ +20˚C (Free ventilation heating setpoint #117 + 0.5˚C).
When heating is activated the bypass is fully (100%) opened.
Then, based on the temperature reading, it closes smoothly if the temperature exceeds the set level.
6.5.2 Passive Cooling
Passive Cooling can be used to cool a building with outdoor air when the room temperature is higher than
the outside temperature and higher than the temp setpoint.
For example, in the summer, during a cool night, the a heated up building may be cooled by outdoor air.
Passive cooling may also be referred to as ‚Free cooling’, as no conventional energy consumptions is needed,
or ‚Night ventilation’ as this type of ventilation mostly happens at night.
Cooling is possible when all of the following conditions are met:
• The outdoor temperature ≤ The extract temperature (room temperature) - 5˚C (Free ventilation outside
offset #118).
Cooling is not possible when one of the following conditions is met:
• The outdoor temperature ≥ The extract temperature (room temperature) - 5˚C (Free ventilation outside
offset #118) +0.5˚C.
Cooling is activated when all of the following conditions are met:
• Cooling is possible.
• The extract temperature (room temperature) ≥+20˚C (Free ventilation heating setpoint #117) + 4˚C
(Free ventilation offset cool setpoint #132).
Cooling is deactivated when one of the following conditions is met:
• Cooling is not possible.
• The extract temperature (room temperature) ≤ +20˚C (Free ventilation heating setpoint #117) + 4˚C
(Free ventilation offset cool setpoint #132) -0.5˚C.
When cooling is activated the bypass is fully (100%) opened.
When the bypass is activated for cooling, fans speed is increased to
25%
if it was below this value.
