Metro Therm Microbooster P, Manual

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1.2. Technical data
1.2.1. General
The unit is composed of a water tank, a refrigerant circuit, a cabinet and a display that
is connected to a control board. The main scope of the appliance is to heat water
stored in a tank.
1.2.2. Operation
The unit is programmed to start heating the water inside the tank when its tempera-
ture falls below a predetermined level. The unit stops when the water temperature
reaches a set point that can be regulated by the user. In general, the appliance is
designed to produce enough hot water to cover the need of a household of 4 persons
or more.
There are two main ways in which the unit can heat the water. These are determined by
the temperature of the heat source upon entry:
1) Internal coil operation (Heat source temperature > Domestic hot water tempera-
ture)
This mode of operation only applies to models with internal coil. If the heat source has
a temperature above the domestic hot water temperature upon entry, it can be used
to pre-heat the water in the tank. This is done by directing the heat source through an
internal coil in the water tank, thereby transferring heat from the heat source to the
domestic water. The cooled heat source is then sent through the refrigerant cycle (as
seen in paragraph 1.2.3). Using the heat source to pre-heat the domestic water boosts
the efficiency of the heat pump.
2) Heat pump operation (Heat source temperature < Domestic hot water temperature)
When the heat source enters the unit at a temperature below the domestic hot water
temperature, only the heat pump operation is used. In the operation with heat pump, a
refrigerant cycle utilizes the operation of a compressor and a heat source at low tem-
perature to heat the water in the tank to a higher temperature level.