Melt Function; Rail Heat - Danfoss AK-CC55 Water Loop User Manual

AK-CC55 Water Loop
Coordination via data communication
Here the system manager handles the coordination. The controllers are gathered in defrosting groups and the
system manager ensures that defrosting is started in the group according to a weekly schedule.
When a controller has completed defrosting, it sends a message to the system manager and then goes into a
waiting position. When the last controller ends defrosting the defrost sequence will continue with drip delay.

Melt function

This function will prevent the air flow in the evaporator from being reduced by frost created by uninterrupted
operation for a long time.
The function is activated if the thermostat temperature has remained in the range between -5 °C and +10 °C for a
longer period than the set melting interval. The refrigeration will then be stopped during the set melting period.
The frost will be melted so that the air flow and hence the evaporator's capacity will be greatly improved.

Rail heat

It is possible to pulse-control the power to the rail heat in order to save energy. Pulse control can either be
controlled according to day/night load or dewpoint.
Relay or analogue output
A relay output can be used when long cycle times are permitted. If fast pulsing is required, the AO1/PWM output
can be used. The output must be connected to an external power solid state relay. The cycle time must be
configured for the relay output in o43 or for analogue output in P82.
Pulse control according to day and night
Various ON periods can be set for day and night operation. A cycle time is set as well as the percentage part of the
period in which the rail heat is ON.
Figure 33: Rail heat control, day/night load.
Pulse control according to dewpoint
In order to use this function, a system manager of the type AK-SM is required which can measure ambient
temperature and humidity to calculate dewpoint and distribute to the appliance controllers. For this the rail heat's
ON period is controlled according to the distributed dewpoint.
Two dewpoint values are set in the appliance control:
• One where the effect must be max. i.e. 100%. (o87)
• One where the effect must be min. (o86)
At a dewpoint which is equal to or lower than the value in o86, the effect will be the value indicated in o88. In the
area between the two dewpoint values, the controller will manage the power to be supplied to the rail heat.
© Danfoss | Climate Solutions | 2022.04 BC378540472015en-000101 | 22