Technical data
52 | Project planning manual for heat pumps for heating and domestic hot water preparation | 01.2012 www.dimplex.de
4.3.3 Water-to-water heat pump
4.3.3 Heat exchanger for the protection of the heat pump
The external heat exchanger must be suitable for the heat pump
used as well as for the prevailing temperature level and water
quality. In the simplest case, the heat exchanger consists of PE
pipes which are installed directly in the cooling water, thus requir-
ing no additional cooling water pump. This cost-efficient alterna-
tive can be used as long as the cooling water pool is large
enough.
Otherwise, screwed plate heat exchangers must be used.
The heat exchanger is dimensioned according to the following
parameters:
Water quality
Range of operating temperatures
Refrigeration capacity of the heat pump type in use
Primary and secondary circuit water flow
NOTE
When using aggressive media (e.g. sea water) as a heat source, titanium
plate heat exchangers must be used.
From software version "J01", the brine limit protection of a brine-
to-water heat pump can be adjusted. When the standard value is
raised from -8 °C to 0 °C, the heat pump is switched off at brine
outlet temperatures below 0 °C.
Heat exchanger installation
For optimal heat transfer, the heat exchangers must be con-
nected in counter flow principle. They must still be protected from
soiling. To this end, a dirt trap with a mesh size of > 0.6mm must
be installed in front of each heat exchanger inlet. Compensators
should be used to reduce the transfer of solid-borne noise.
Maintenance of the heat exchanger
Soiling may occur on the heat exchanger depending on the hard-
ness or soiling in the water. This reduces the output of the heat
exchanger. To prevent this from happening, the heat exchanger
must be cleaned in regular intervals. The so-called CIP process
(Cleaning-In-Place) is used here - the heat exchanger is rinsed
on-site with a mild acid, such as formic acid, itric acid or acetic
acid, to remove any deposits.
NOTE
It is advisable to check the heat exchanger for soiling at least every two
years.