Danfoss DHP-H, Installation And Service Instructions Manual

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VMBMA602
Service instructions
12 The heat pump
12.1 Function description
A heat pump utilises the free energy found in a natural heat source, such as rock, ground, ground water or air. The heat pump can be com-
pared to a reversed refrigerator. In a refrigerator, heat is transferred from the inside of the refrigerator to the outside. In a heat pump the
heat that is stored in a heat source is transferred to the inside of the house. The heat pump uses the energy in the heat source and gives
back two to three times more heat energy than what it uses in electrical energy. The heat pump is, therefore, a very environmentally friend-
ly and economical way of heating a house.
In order for the heat pump to be able to retrieve heating energy from the heat source and transfer it to the heating system of the house,
three separate fluid circuits are required.
The circuit that retrieves the heating energy from the heat source is called the brine circuit and it maintains a low outgoing temperature to
be heated by the heat source.
The next circuit is called the refrigerant circuit and is a closed circuit which takes the retrieves heating energy and transfers it to the last cir-
cuit, the heat transfer fluid circuit.
The heat transfer fluid circuit holds the fluid that circulates in the heating system of the house and transfers heating energy to the house or
heat pump’s water heater.
The figure below shows how the different circuits work together in the transfer of heating energy.
Function principles of a heat pump. Figure 78:
1 A fluid (brine) filled hose is lowered into a lake, buried in the ground or lowered into bedrock. The brine obtains energy from the heat
source by the fluid temperature in the hose being heated a few degrees by the surrounding heat source. The fluid filled hose is also
known as a collector.
2 The brine is guided into the heat pump’s evaporator. The enclosed refrigerant in the refrigerant circuit is forced to boil as the pressure
in the expansion valve drops and later evaporates to a gas in the evaporator. The energy produced during this process is released by
the slightly heated brine.
3 The refrigerant that now contains a large quantity of energy in the form of heat is transferred to the compressor, which both increases
its temperature and pressure.
4 The refrigerant then continues to the condenser. When condensing, the refrigerant supplies its heat energy to the heat transfer fluid
circuit. The refrigerant’s temperature decreases and returns to a liquid state.
5 The heat transfer fluid circuit transports the heat energy out to the water heater, radiator and the under floor heating system, which
heat up.
6 The refrigerant is then transported through the expansion valve where the pressure drops and the refrigerant starts to boil and then
the process starts again.
12.2 Components
The heat pump is a complete heat pump installation for heating and hot water. It has the market’s first compressor developed solely for
heat pumps. It has an integrated 180 litre water heater and auxiliary heating. TWS stands for Tap Water Stratificator. This technology results
in more effective heat transfer and more effective layering of the water in the water heater.
The heat pump is equipped with control equipment, which is controlled via a control panel.
Heat enters the house via a water borne heating system, a low temperature system. The heat pump supplies as much of the heat demand
as possible before auxiliary heating is engaged and assists.
The heat pump unit consists of five basic units:
Expansion valve/
pressure drop
Enclosed
refrigerant
Compressor/
pressure increasing
Brine
Condenser
Evaporator
Heat transfer fluid circuit – is the circuit that contains
the water that transports the heat/energy to the heating
system and the water heater.
Refrigerant circuit – is the circuit that contains a chlorine
and freon free refrigerant which, inside the heat pump,
transfers the energy retrieved from the brine circuit
through evaporation, compression and condensation,
and supplies it to the heat transfer fluid circuit.
Brine circuit – is the circuit that contains an antifreeze
water based mix that obtains and transports energy from
the heat source to the heat pump. This circuit is also
known as the collector.
Rock, ground, ground
water or air
Heating system and
water heater