Danfoss DHP-AT, Инструкция по установке и обслуживанию

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4.3.5 Legionella prevention
There is an automatic legionella prevention when the heat pump function is set for DHW. Run at
00:00 after 7 days of operation. It w ill then heat up the hot water tank to 65 degrees for 15 minutes.
This is repeated once a week and kills any possible legionella bac terias in the water inside the
hot water tank.
4.3.6 Frost protection
There is an automatic frost protection function in the unit that works in two steps. When there is a risk of freezing
due to low temperatures, the unit will first start the water pump to create a water flow in the system. Next step is
to automatically start the heating operation.
•
Frost protection, step 1
When the operational status of the heat pump is Standby or powered ON, the outside ambient air temperature is
below 2°C, the return water temperature is below 8°C, the unit will automatically start operating in water pump
mode. It will exit the frost protection when the ambient air temperature is more than 3°C or the return water tem-
perature has reached over 10°C. When this protective function is triggered, the controller will display "Err 19", but
this is not a fault. The unit will automatically recover when the conditions meet the settings in the control system.
•
Frost protection, step 2
When the return water temperature is less than 6°C, the unit will automatically start heating operation. It will exit
step 2 protection when the ambient temperature is more than 3°C or the return water temperature is more than
15°C. When this protective function is triggered, the controller will display the "Err 18", but this is not a fault. The
unit will automatically recover when the conditions meet the settings in the control system.
When the operational status of the heat pump is Standby or powered ON, the machine will start domestic hot
water function compulsorily if water tank temperature is below 13°C; then exit and return to previous status when
the water temperature is more than 16°C. The controller will display "Err 18", but this is not a fault. The unit will
automatically recover when the conditions meet the settings in the control system again.
4.4 Check and safety functions
The heat pump has a number of safety functions to protect the installation against damage during abnormal oper-
ating conditions:
•
Water flow switch protection
•
Phase sequence fault/Overcurrent protection
•
Excessive temperature difference protection of outlet and return water
•
Internal heater overheat protection
•
High pressure protection
•
Low pressure protection
•
Outlet water temperature overheat protection
•
Outlet water temperature subcooling protection
•
Exhaust gas temperature overheat protection
•
Frost 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 seizes, this is detected by the control system and the heat pump begins to work
according to the settings in the control system.
Electrical system
The electrical panel inside the heat pump is fused with a 5A/250V AC fuse (dimension: 5*20; model: 522).
4.5 Heating curves
The heat pump will automatically adjust the water temperature according to the following:
Installation and service instructions VMGFI202 – 15