Technical data

www.dimplex.de 01.2012 | Project planning manual for heat pumps for heating and domestic hot water preparation | 131
Help with planning and installation 10.1
10 Help with planning and installation
10.1 Pipework dimensioner
In order to minimise the pressure drops and thus the power con-
sumption of the circulating pumps, the pipe cross sections must
be dimensioned accordingly. The specific pressure drop per pipe
meter and the flow velocity of the medium in the pipe – both
based on the nominal volume flow – are used as designing crite-
ria.
The following guideline values should not be exceeded:
 dpmax = 120 Pa/m
 from pipework DN 10 to DN 65 wmax = 0.7 m/s
 from pipework DN 80 to DN 125 wmax = 1.2 m/s
 from pipework DN 150 wmax = 2.0 m/s
Fig. 10.1: Dimplex pipework dimensioner
ATTENTION!
The approximate pipework dimension can be determined using the
diagram. The approximate values do not replace a pipework network
calculation. The pressure drop determined in the pipework calculation
are required in addition to the circulating pump design.
NOTE
The pressure drop in the system is increased when water-glycol mixtures
are used. This must be taken into account in the pump design.
NOTE
When using composite pipes, higher pressure drops must be taken into
consideration due to the significantly reduced cross-sections on the
moulded parts. For pipework sections with a large number of moulded
parts, a pipework diameter with at least one dimension larger must be se-
lected. The pressure drop should also be kept as low as possible when
designing additional pipework components (check valves, two and three-
way reversing valves).
NOTE
Special planning instructions for efficient heat pump system operation
and the Dimplex pipework dimensioner are available to download at
www.dimplex.de/professional/online-planer/hydraulische-einbindungen.
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