eta PelletsCompact PC33, Installation Manual

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Connection between multiple buffer storage tanks Buffer storage tank
Serial connection
A serial connection between two buffers has no
advantages over a parallel connection; but it does dis-
advantages. For example, a suspended hot water tank
can get no heat from the second buffer or an internal
heat exchanger cannot heat to both buffers. For this
reason, with serial buffers one should connect the
solar heating system using either heat exchangers in
both buffers or (preferred) with an external heat
exchanger.
1 Flow
2 Return
With rare exceptions, the use of the serial connection
(buffer 2 top and buffer 1 bottom connected) is limited
to overcoming spatial constraints of a particular instal-
lation. If passage to a door must be kept free or if there
is a long distances between buffers, only a serial
connection will be possible
Tichelmann connection for higher outputs
For parallel connection with one-sided connection, the
volume of the second buffer is integrated using the
thermosiphon principle. The exchange between the
two tanks is driven only by gravity and limited by the
hydraulic resistance of the junctions. Therefore, a
Tichelmann connection is required for medium
outputs.
With a 6/4" connection, a maximum of 5500 l/h at
0.25 mws pressure loss is possible (for flow and return
connections together). This corresponds to 130 kW at
a spread of 20 °C. Therefore, external piping (either
symmetric or with Tichelmann connection), is needed
for higher outputs.
With more than two tanks, external piping with
Tichelmann connection is also needed to fill and drain
all tanks uniformly.
Parallel connection
between buffer stor-
age tanks
Buffer con-
nections
5/4" DN 32
Buffer con-
nections
6/4" DN 40
one-sided connection
< 25 kW boil-
er output
maximum 2
buffers
< 40 kW boil-
er output
maximum 2
buffers
Internal Tichelmann con-
nection
< 80 kW boil-
er output
maximum 2
buffers
< 130 kW
boiler output
maximum 2
buffers
Symmetrical connection
> 80 kW boil-
er output
maximum 2
buffers
> 130 kW
boiler output
maximum 2
buffers
external piping with
Tichelmann connection > 80 kW boil-
er output,
and/or more
than 2 buf-
fers
> 130 kW
boiler output,
and/or more
than 2 buf-
fers