Danfoss DHP-AT, Installation Manual

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Caution
It is important to be aware of the freezing risk when running the system in MANUAL mode as certain control
functions may have been turned off completely or set in a manual mode.
4.4 Check and safety functions
The heat pump has a number of safety functions to protect the heat pump and the installation against damage during abnormal operat-
ing conditions:
▪
Internal fuse for current limitation in electrical system
▪
Water flow switch protection in heat transfer fluid circuit
▪
Internal electrical heater overheat protection in heat transfer fluid circuit
▪
High pressure protection in refrigeration circuit
▪
Low pressure protection in refrigeration circuit
▪
Compressor exhaust gas temperature overheat protection in refrigeration circuit
▪
Fan motor temperature protection
Depending on the condition, the heat system will stop completely or electrical heaters will start and the system continues to work but
with limited capacity. Error codes will be displayed to inform the user about the problem. When the abnormal condition ceases, it is
detected by the control system and the heat pump begins to work according to the settings in the control system, unless a safety func-
tion is triggered that requires manual reset.
The diagram below shows the heat pump's three circuits with respective safety functions.
1
3
6
5
7
8
4
9
2
10
12
11
Fig. 6: Check and safety functions
Position Name
1 Heat transfer fluid circuit
2 Flow switch
3 Safety valve, heat transfer fluid circuit, externally
mounted
4 Refrigerant circuit
5 Over-pressure bypass valve from high pressure
side to low pressure side
6 High pressure switch
7 Low pressure switch
8 Compressor
9 Fan
10 Discharge pipe sensor
11 Internal electrical heater with overheating protec-
tion
12 Ambient air source
Electrical system
The electrical cabinet inside the heat pump is fused with a 5A/250V AC fuse (dimension: 5*20; model: 522).
Heat transfer fluid circuit (1)
If the flow in the heat transfer fluid circuit is below the permitted value, detected by the flow switch (2), the heat pump's normal opera-
tion is blocked. An alarm indicator on the control unit control panel flashes and an error code appears in the control panel display. The
alarm resets itself when the flow returns.
If the pressure in this circuit exceeds the opening pressure for the safety valve (3), the valve opens, releases the over-pressure and closes
again. The safety valve overflow pipe must have an open connection to the drain and visibly flow into this in a frost-free environment.
The safety valve (3) is not an integrated part of the product, but a required external protection function that must installed at commis-
sioning and in accordance with local regulations.
Refrigerant circuit (4)
Installation Guide DHP-AT
VMGFI302 Danfoss Heating Solutions
16