Installation - Dhw Cylinders 6.1 Connection On The Dhw Side; General Information - Viessmann Vitocell 300-H Technical Manual

Installation — DHW cylinders
6.1 Connection on the DHW side

General information

See the diagrams from page 36 or 42 regarding the connection
on the DHW side of DHW cylinders installed as a cylinder bank.
Fittings that are installed in the connection line must conform to
DIN 1988 (see diagrams on page 34) and DIN 4753 [or local regu-
lations].
These fittings comprise the following:
■ Shut-off valves
■ Drain valve
■ Pressure reducer
■ Safety valve
■ Non-return valve
■ Pressure gauge
■ Flow regulating valve
■ Drinking water filter
Pressure reducer (to DIN 1988)
Install this device if the pressure in the pipework at the connection
point exceeds 80 % of the safety valve response pressure.
It is advisable to install the pressure reducer immediately down-
stream of the water meter. This creates nearly the same pressures in
the entire DHW system, which is thereby protected against overpres-
sure and water hammer.
According to DIN 4109, the static pressure of the water supply sys-
tem after distribution over the various floors upstream of the fittings
should not be higher than 5 bar (0.5 MPa).
Safety valve
The system must be equipped with a type-tested diaphragm safety
valve as protection against overpressure.
Permissible operating pressure: 10 bar (1 MPa).
The connection diameter of the safety valve must be as follows:
■ Up to 200 l capacity
min. R ½ (DN 15),
max. heat input 75 kW,
■ Between 200 and 1000 l capacity
min. R ¾ (DN 20),
max. heat input 150 kW,
■ Between 1000 and 5000 l capacity
min. R 1 (DN 25),
max. heat input 250 kW.
DHW heating
Install the safety valve in the cold water line. It must not be able to
be isolated from the DHW cylinder or the cylinder bank. There must
be no constrictions in the pipework between the safety valve and the
DHW cylinder. Never seal off the safety valve discharge pipe.
Ensure that any expelled water is safely and visibly drained into a
drainage system. Position a sign close to the safety valve discharge
pipe, or ideally on the safety valve itself, with the following inscrip-
tion:
"For safety reasons, water may be discharged from the discharge
pipe during heating. Never seal off."
Recommendation: Install the safety valve above the top edge of the
cylinder. Then the DHW cylinder will not need to be drained when
working on the safety valve.
Non-return valve
This prevents system water and heated water from flowing back into
the cold water pipe and into the mains water supply.
Pressure gauge
Provide a connection for a pressure gauge.
Flow regulating valve
We recommend that a flow regulating valve is installed and the maxi-
mum water flow rate is adjusted in accordance with the 10-minute
peak output of the DHW cylinder.
Drinking water filter
Install a drinking water filter in accordance with DIN 1988. The instal-
lation of a drinking water filter prevents dirt from being introduced
into the drinking water system.
Only for cylinder banks Vitocell 300-H:
With DHW outlet temperatures in excess of 60 °C, the connection
line on the DHW side can also be connected in series, in multi cylin-
der banks. Connect the connection line on the heating water side as
shown in the diagrams on page 41.
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VIESMANN
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