Control System Strategy - Dantherm HCV 300 Manual

INSTALLATION & SERVICE MANUAL FOR PROFESSIONALS
Product description: Control system strategy

Control system strategy

Introduction
This section describes the control system strategy under different conditions.
Preheat
If a preheater is installed, the unit can add electrical heating to T1 outdoor air to reduce de-
frosting situations and increase the supply air temperature.
• Preheating is applied after the T1 sensor.
• If the outdoor air is < -3 °C, or supply air is < 16.5 °C, the preheater will be activated at 10%
• The preheating effect will increase/decrease by 10% every 60 seconds depending on
The set points for the temperatures during operation with an active preheating surface are
fixed and cannot be changed.
Defrosting/wood- In cold conditions where T1 is below -3 °C, and exhaust air T4 is < +2 °C, condensate could
burner function build up as ice in the heat exchanger.
The following procedure is initiated to avoid this if preheating is not installed:
• The supply air fan speed will decrease until the minimum RPM is reached.
• After 10 seconds, the supply air fan will stop completely while the extract air fan
• When T4 is > +8 °C again, the supply air fan will start at minimum RPM and
• This procedure is repeated as long as necessary.
• If T1 is ≤ -13 °C for more than 4 minutes 25 seconds, even with defrost mode activated,
Defrosting operation will lead to a negative pressure inside the house. This may cause
smoke, for example from a woodburning stove, to be drawn back into the house. If
woodburner mode is activated and there is still a need for the defrosting function to be
active, the unit will instead stop all operation for four hours.
Setpoints for defrosting cannot be changed.
When defrosting is active HRC 3 will show "dEF" in the display.
When defrosting has shut down everything, the display will flash the T1 temperature
See "Temporary Modes (Override)" section on pagepage 121 and pagepage 122.
Bypass cooling
and summer mode
of its maximum capacity.
temperature conditions.
continues to run continuously to remove any ice.
increase speed until the originally requested speed is reached.
the unit will stop all operation for 30 minutes and will then attempt to start under the
previous operating conditions. If electrical preheating is connected, operation stop mode
is disabled.
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