eta 13180 LP-D, Installation Manual

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Hydraulic integration Buffer storage tank
• An automatic heating boiler up to 500 kW rated
capacity requires a minimum buffer volume of
25 litres per kW rated capacity.
Hence, a wood chip boiler with 100 kW needs a
minimum buffer volume of 2500 l (=100x25).
However,pellet boilers up to 70 kW rated
thermal input are exempt from this regulation.
8.2 Hydraulic integration
Hydraulic integration of a buffer
For the largest possible buffer storage capacity and for
maximum solar yield even in winter, low return tem-
peratures from the consumers are the goal.
Even the best stratified buffer can't unmix what has
been mixed by heat distributors. Particularly in houses
where radiators and underfloor circuits are present, no
mixing heat distributors should be installed; the returns
should be connected directly to the buffer. An
underfloor heating system can still be operated with
the return from radiators.
If a solar heating system is connected, only the cold
returns from an underfloor heating system or from a
fresh water module may be fed into the solar-heated
lower third of the buffer. This results in lower solar
panel working temperatures with significantly higher
efficiencies and also significantly higher solar yield.
In all cases, an oil or gas boiler should be connected at
the top part of the buffer only.
Siphon loops downwards at all connections reduce
heat losses in summer.