Danfoss DHP-AT, Installation And Service Instructions Manual

Page: 15 / 38

•
During house heating:
•
o
When the air temperature is below 0°C.
o
The system requests heating operation.
o
The buffer tank temperature has decreased more than the value set in Menu 08 and 30 minutes after the
compressor has started
o
After another 90 minutes;
- If the air temperature is still below 0°C.
- If the system still requests heating operation.
- If the buffer tank temperature has decreased less than the value set in Menu 08.
-
If the buffer tank temperature still has not reached the temperature measured at compressor startup.
o
During house heating operation, if the heat pump has stopped as a protection due to a failure and the
system does not reach the temperature setting, an automatic start of the internal electrical heater is trig-
gered.
The internal electrical heater will stop in any of the following conditions:
•
If the DHW electrical heater in the water tank starts.
•
Water flow switch failure
•
Standby (and not going into frost protection, step 2)
•
Non house heating mode (for example, cooling)
•
Air temperature sensor failure
•
Buffer tank temperature sensor failure
•
Air temperature more than 0°C
•
The buffer tank temperature is higher than the temperature setting
4.3.1.2 Start and stop conditions, heating belts
When the outside temperature is low and to prevent freezing of refrigerant, heatings belts will start to work to
keep the temperatures in the heat pump withing a safe range.
4.3.1.2.1 Evaporator heating belt
The drain heater starts if all of the following conditions are fullfilled:
•
Power is on, and the operation is heating or domestic hot water
•
Compressor starts
•
The air temperature is below 1°C
The drain heater stops in any of the following conditions:
•
Non heating operation (for example, cooling)
•
Compressor has stopped for more than 30 minutes
•
The air temperature is higher than 4°C
4.3.2 Cooling
The heat pump can be set to cooling within an outside air temperature range between 8-43°C. Beyond this range
the heat pump will stop. In temperatures below 16°C, condensate problems may occur and which must be taken
care of by drainage solutions as well as isolation of water tanks and piping.
4.3.3 Domestic hot water
It is possible to produce Domestic Hot Water (DHW) by installing a heat system with a reversing valve and possibly
a hot water tank.
When the operation is house heating/DHW AUTO mode and the water temperature in the water tank decreases
more degrees than the allowed setting in the control system, the heat pump switches to produce hot water. When
the temperature reaches the setpoint again , the heat pump returns to house heating.
The maximum water temperature is 55°C. If the water temperature rises above 55°C, the heat pump will automati-
cally go into protection mode. Considering energy saving, it is recommended to set the DHW temperature below
55°C (60°C if there is an electrical heater installed inside the hot water tank).
Installation and service instructions VMGFI202 – 13