Dimplex LA 3860 Installation And Operating Instruction page 9

LA 3860
Scale formation in domestic hot water heating systems cannot
be avoided, but in systems with flow temperatures below 60 °C,
the problem can be disregarded. With high-temperature heat
pumps and in particular with bivalent systems in the higher per-
formance range (heat pump + boiler combination), flow tem-
peratures of 60 °C and more can be achieved. The following
standard values should therefore be adhered to with regard to
the filling and make-up water according to VDI 2035, sheet 1:
The total hardness values can be found in the table.
Filling and supplementary water as well as heating water, depending on
heat output
Overall heat output in kW
50
specific water content
2
heat generator > 0.3 k per kW
50
specific water content
2
heat generator > 0.3 k per kW
(e.g. circulating water heaters)
and systems with electric heat-
ing elements
> 50 kW to 200 kW
> 200 kW to 600 kW
> 600 kW
Heating water, depending on heating output
Operating mode
3
Low-salt
Containing salt
Materials in the system
Without aluminium alloys
With aluminium alloys
1. For the purpose of calculating the specific system volume, the smallest indi-
vidual heat output is to be used for systems with several heat generators.
2. In systems with several heat generators with different specific water con-
tents, the smallest specific water content is decisive.
3. For systems with aluminium alloys, full softening is recommended.
Fig. 6.1:Guideline values for filling and make-up water in accordance with
VDI 2035
For systems with an above-average specific system volume of
50 l/kW, VDI 2035 recommends using fully demineralized
water and a pH stabiliser to minimize the risk of corrosion in the
heat pump and the heating system.
CAUTION!
With fully demineralized water, it is important to ensure that
the minimum permissible pH value of 7.5 (minimum
permissible value for copper) is complied with. Failure to
comply with this value can result in the heat pump being
destroyed.
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Total alkaline earths in mol/m³
(Total hardness in dGH)
Specific system volume in l/kW
1
Heat output
 20 20 to 50 50
3.0 (16.8)
none
 3.0 (16.8) 1.5 (8.4)
< 0.05 (0.3)
2.0 (11.2) 1.0 (5.6)
1.5 (8.4
< 0.05 (0.3)
< 0.05 (0.3)
Electrical conductivity in µS/cm
> 10 to  100
> 100 to  1500
Appearance
clear, free from sedimentary substances
pH value
8.2 to 10.0
8.2 to 9.0
452167.66.48-EN · FD 0212
Note:
The hot water connections must be established according to
the dimensional drawing (see Cap. 13.1 on page 14) in the
countercurrent principle.
Important:
The notes/settings in the instructions of the heat pump man-
ager must always be observed and carried out accordingly; not
doing so will lead to malfunctions.
Minimum heating water flow rate
The minimum heating water flow rate through the heat pump
must be assured in all operating states of the heating system.
This can be accomplished, for example, by installing either a
dual differential pressureless manifold or an overflow valve. The
procedure for setting an overflow valve is described in the
chapter "Commissioning". When the minimum heating water
flow rate is undershot, the plate heat exchanger in the refriger-
ation circuit can freeze, which can lead to total loss of the heat
pump.
The nominal flow rate is specified depending on the max. flow
temperature in the device information and must be taken into
account during planning.
The specified "Minimum heating water flow rate for pump siz-
ing" (See "Device information" on page 11.) must be ensured
during defrosting and cooling operation. An installed flow rate
switch is used only for switching off the heat pump in the event
of an unusual and abrupt drop in the heating water flow rate
and not to monitor and safeguard the nominal flow rate.
Antifreeze
Heat pump systems, which cannot be guaranteed to be frost-
free, should be equipped with a drainage option (see Fig.). The
antifreeze function of the heat pump manager is active when-
ever the heat pump manager and the heat circulating pump are
ready for operation. When decommissioning the heat pump, or
in the event of a power failure, the system must be drained
through the indicated points (see illustration); it may be neces-
sary to purge the system with compressed air. The heating cir-
cuit should be operated with a suitable antifreeze if heat pump
systems are implemented in buildings where a power failure
cannot be detected (holiday home).
3
English
2
1
EN-7