Installation manual

148
6.1.2
Sharp-edged metal objects must on no account be used for
cleaning.
The operational reliability of the safety valve should be checked
at regular intervals. We recommend having an annual service
inspection carried out by a qualified specialist company.
Thermal insulation and covering
The thermal insulation is made of high-grade rigid polyurethane
foam. The use of this material results in minimal stand-by losses.
Regulation
The cylinders are equipped as standard with a sensor with an
approx. 5 m long connecting lead which is connected directly to
the heat pump manager. The characteristic curve of the sensor
complies with DIN 44574. The heat pump manager regulates the
temperature settings and the time-controlled loading and
reheating with the flange heater. Attention should be paid to the
hysteresis when setting the hot water temperature. It should
also be noted that the measured temperature will rise slightly
because the thermal processes in the cylinder still require some
time to equalize after the domestic hot water has been heated.
Regulation can also be carried out using a thermostat. The
hysteresis should not exceed 2 K.
Operating conditions:
Installation
Assembly is limited to connecting the hydraulic components of
the system along with its respective safety devices and to
connecting the sensor.
Accessories
Electrical flange heater for thermal reheating if required or
desired.
Electrical installations should only be connected by authorised
electricians according to the corresponding circuit diagram. The
relevant regulations according to the Technical Specifications for
Electrical Installations (TAB) and the guidelines of the
Association of German Engineers (VDI) should be observed.
Installation location
The cylinder should only be installed in a room protected from
frost. Installation and start-up must be carried out by an
authorised specialist.
Water pipe connections
The cold water pipes are connected according to DIN 1988 and
DIN 4573 Part 1 (see Fig. 6.1 on p. 149). All connecting pipes
should be joined using pipe unions.
A circulation pipe should only be connected if the domestic water
supply system is extensive because it causes high stand-by
losses. If a circulation system is required, it should be fitted with
an automatic device to interrupt the circulation.
All connecting pipes including fittings (with the exception of the
cold water connection) must be protected against heat losses
according to the German Federal Energy Efficiency Ordinance
(EnEV). Poorly insulated or uninsulated connecting pipes will
lead to a loss of energy which is many times greater than the
energy loss of the cylinder.
A check valve should always be fitted to the heating water
connection to prevent the cylinder from heating up or cooling
down uncontrollably.
The air outlet pipe of the safety valve connected to the cold water
pipe must always remain unblocked. The operational readiness
of the safety valve should be checked at regular intervals by
venting it.
Drainage
A means of draining the cylinder should be provided in the cold
water connecting pipe during construction.
Pressure reducing valve
It is essential to equip the connecting pipe with a pressure
reducing valve if the max. supply pressure could exceed the
permissible operating overpressure of 10 bar. However,
according to DIN 4709, the pipe pressure should be lowered
inside buildings to a level which still permits technical operability
to reduce the generation of noise. Depending on the type of
building, it may then be worthwhile to install a pressure reducing
valve in the cylinder inlet.
Safety valve
A tested and non-closing safety valve should be installed where
the cylinder is connected to the system. No constrictions, e.g.
dirt traps, should be installed between the cylinder and the safety
valve.
Water should be able to flow (drip) out of the safety valve when
the cylinder is being heated up to compensate for the expansion
of the water and to prevent a severe build-up in pressure. The
safety valve overflow pipe must flow freely into a sewage system
without any constrictions. The safety valve should be mounted in
an easily accessible and observable location so that it can be
vented during operation of the system. A sign should be fixed on
the valve itself or in its vicinity with the following inscription:
“Water may be discharged from the air outlet pipe during heating!
Do not close!”
Use only spring-loaded diaphragm safety valves that have been
tested.
The air outlet pipe should have at least the same cross section as
the safety valve outlet. If it is necessary for the air outlet circuit to
have more than two bends or if it is more than 2 m in length, an
air outlet pipe in the next largest nominal size should be selected.
It is not permissible for the air outlet circuit to have more than
three bends or to be more than 4 m in length. The cross section
of the outlet pipe located downstream from the collecting hopper
must be at least twice the size of the cross section of the valve
inlet. The safety valve must be adjusted so that the permissible
operating overpressure of 10 bar is not exceeded.
Check valve, test valve
A check vale (return flow inhibitor) must be installed to prevent
the heated water from flowing back into the cold water pipe. Its
function can be tested by closing the first shutoff valve in the
direction of flow and opening the test valve. Only the water
contained in the short piece of pipe should be discharged.
Shutoff valves
As illustrated in Fig. 6.1 on p. 149, shutoff valves are to be
installed on the cylinder in both the cold and hot water pipes as
well as in the heating water flow and return flow.
Permissible operating overpressure
Heating water 3 bar
Domestic water 10 bar
Permissible operating temperature
Heating water 110 °C
Domestic water 95 °C