Installation manual

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Domestic Hot Water Preparation and Ventilation with Heat Pumps 6.1.2
6 Domestic Hot Water Preparation and Ventilation with Heat
Pumps
6.1 Domestic Hot Water Heating with the Heat Pumps for Heating Purposes
The heat pump manager regulates both space heating as well as
the preparation of domestic hot water (see chapter on
regulation). The system for heating domestic hot water using the
heat pump should be set up parallel to the system for space
heating, because a different hot water temperature is normally
required for hot water preparation than for space heating. The
return flow sensor should be installed in the common return flow
of the heating system and the domestic hot water heating system
(see chapter on integration).
6.1.1 Requirements placed on the domestic hot water cylinder
The standard continuous power ratings specified by the different
cylinder manufacturers are not suitable criteria for selecting a
cylinder for heat pump operation. The following criteria must be
taken into consideration when selecting a cylinder: the size of the
heat exchanger area, the construction and the layout of the heat
exchanger in the cylinder, the continuous power rating, the flow
rate and the installation position of the thermostat or sensor.
The following criteria must be taken into
consideration:
 Heating up stationary hot water (covering water level losses
- static state)
 The heat output of the heat pump at the maximum heat
source temperature (e.g. air +35 °C) must also be
transferable at a cylinder temperature of +45 °C.
 The cylinder temperature is lowered when a circulation pipe
is used. The circulation pump should be time-controlled.
 It must be possible to tap the required amount of hot water
even during shut-off times without the heat pump having to
reheat.
 Selective reheating using a flange heater is only possible in
combination with a temperature sensor.
6.1.2 Domestic hot water cylinder for heat pumps for heating purposes
The domestic hot water cylinders are used to heat the water for
sanitary facilities. This is carried out indirectly using the heating
water flowing in an integral coiled tubing.
Construction
The tanks are manufactured in a cylindrical design according to
DIN 4753 Part 1. The heating surface is a welded, spiral-shaped
pipe coil. All connections lead out from one side of the cylinder.
Corrosion protection
According to DIN 4753 Part 3, the entire interior surface of the
cylinders is protected by an approved enamel coating. This
enamelling is applied in a special process, and guarantees
reliable corrosion protection in combination with the magnesium
anode which is fitted as an accessory.
According to the specifications of the German Technical and
Scientific Association for Gas and Water (DVGW), the
magnesium anode should be initially inspected by after-sales
service after 2 years of use and then in regular intervals. It should
be replaced according to need. Depending on the quality of the
domestic water (conductivity), it is advisable to have the reactive
anode inspected in shorter intervals.
The anode (33 mm) should be replaced once it has reduced in
size to a diameter of 10-15 mm.
Water hardness
Domestic water contains varying amounts of lime depending on
its source. Hard water contains a large amount of lime. There are
different water hardness levels which, in Germany, are
measured in degrees of hardness (°dH).
“French degrees of hardness” are used in Switzerland. These
correspond to
If electric flange heaters are used for general reheating to
temperatures over 50 °C, we recommend the installation of a
descaling system for water if the water supply has hardness level
III with a hardness of > 14 °d.H. (hard and very hard water) or
more.
Start-Up
Ensure that the water supply is turned on and the tank is filled
before start-up. The initial filling and start-up must be carried out
by a qualified specialist company. The entire system including all
factory-assembled components should be inspected to ensure
that everything is working properly and that there is no leakage.
Cleaning and maintenance
The mandatory cleaning intervals vary according to the water
quality and the temperatures of the heating medium and the
cylinder. We recommended having the tank cleaned and the
system checked once a year. The glass-like surface prevents
extensive build-up of lime scale and enables rapid cleaning using
a powerful water jet. Large pieces of lime scale may only be
broken up using a piece of wood before being rinsed away.
Hardness level 1 = 0 - 7° dH (soft water)
Hardness level II = 8 - 14° dH (normal water)
Hardness level III = 15 - 21° dH (hard water)
Hardness level IV = more than 21° dH (very hard water)
1° d.H. = 1.79° fr.H.
1° fr.H. = 0.56° d.H.