System Operation Strategy - Dantherm HCV 300 Manual

INSTALLATION & SERVICE MANUAL FOR PROFESSIONALS
Product description: System operation strategy

System operation strategy

Introduction
This section describes the operation strategy in various conditions.
Preheat
If a preheater is installed, the unit can add electrical heat to the T1 incoming outside air, in
order to reduce defrost situations, and increase the supply air temperature.
• Preheat is applied after the T1 sensor.
• If outside temperature is < -3°C or supply air is < 16,5°C the preheater will switch on
with 10% power.
• The power will increase/decrease 10% for each 60 seconds depending on the T1 or T2
temperature.
Preheating setpoints are fixed and cannot be changed.
Defrost / fireplace In cold conditions where T1 is below -3°C and exhaust T4 is < +2°C the condensed water
function
could built up as ice in the heat exchanger.
In order to prevent this, following sequence is initiated:
• Apply additional heat with preheater if mounted.
• The supply fan speed will decrease speed until minimum RPM is reached.
• After 10 seconds the supply fan will stop completely, while the ongoing exhaust fan
supplies warmer air into the heat exchanger component, to remove potential ice.
• When T4 yet again is > +8°C the supply fan will start at minimum RPM, and then
increase speed until the original required speed is regained.
• This procedure is repeated as long as necessary.
• If T1 is ≤ -13°C for more than 4 minutes and 25 seconds, even with defrost mode active,
the unit will stop all operation for 30 minutes, and reattempt previous operation
condition. If electrical preheat is present, this total off-mode is disabled.
The defrost operation will create an underpressure inside the house. This may cause
smoke from e.g. a fireplace to be drawn back into the house. If fireplace mode is enabled, the
unit will stop all operation in 4 hours instead.
Setpoints for defrost cannot be changed.
When defrost is active HRC 3 will show "dEF" in the display.
When defrost has shut all off, the display will flash the T1 temperature
Bypass cooling See more in the "Transport and unwrapping" section on page 10 and page 11.
and summer mode
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