Pressure Control By Normally Closed Pressure Switch - Bosch DOMESTIC HOT WATER HEAT PUMP Technical Manual

evaporation cooling. In order to achieve optimum cooling capacity in the evaporator, the refrigerant flow is
controlled by the expansion valve or orifice tube.
The component achieves high durability thanks to welded stainless steel head and stainless steel diaphragm and
contains the gas charge for quick response time adapted to small evaporators.
ATTENTION:
In case of replacement, the component should be protected from the heat during soldering process.
Pict.37 – Expansion valve (cut view)

4.4 Pressure control by normally closed pressure switch

In this closed refrigerant circuit, is very important to be sure about the correct range of temperatures / pressures, in
order to have an efficient system.
Pressure gauges (accessible to the technicians), are permanently installed to allow monitoring compressor suction
(low pressure side) and discharging pressures (high pressure side).
These kinds of connections use throttle valves that prevent against gauge fluctuation when readings are to be
taken. In both sides high and low pressure, the high and low pressure switches will protect the system from
excessively low or high compressor temperatures.
If the pressure drops below a pre-set level, the compressor is stopped and the same valve will allow the system to
start (after reset) when pressure reaches again its safety value. In the other hand, the other pressure switch in the
compressor outlet, will measure the outlet pressure and, in case of excessively high pressures, the compressor is
stopped until the malfunction is solved and pressure decreased.
6720649497 SM HP270-1 2012/09 en
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