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4
System overview
Basic
idea
The
system
solution
available
from
june
2013
can
be
explained
schematic
with
below
picture.
One
or
more
heat
pumps
operate
to
either
of
tank
1
or
tank
2.
This
is
controlled
by
the
changing
valve
between
the
tanks.
Energy
is
transferred
to
the
heating
system
through
1
or
more
4
‐
way
mixing
valves
controlled
by
the
control
unit.
Domestic
hot
water
is
provided
by
curled
copper
pipes,
cold
water
preheated
in
tank
1
and
after
heated
in
tank
2.
If
necessary
also
a
electric
boiler
can
be
connected
in
series
with
the
tanks
hot
water
supply.
Tank
1
Tank
1
is
the
primary
energy
storage
and
supplier
of
heat
to
the
heating
system.
As
heating
systems
demands
different
temperatures
depending
on
ambient
conditions
the
temperature
in
tank
1
will
be
of
a
floating
nature,
i.e.
temperature
demand
will
be
different
depending
on
the
conditions.
This
floating
behavior
is
realized
by
using
a
heating
curve
that
adapts
to
ambient
conditions,
mostly
outdoor
temperature.
For
each
of
the
3
heating
system
controls
available,
it’s
possible
to
set
a
unique
heating
curve.
Heat
pumps
will
operate
to
the
demanded
temperature
plus
a
set
temperature
difference.
Tank
2
Tank
2
primary
task
is
to
provide
enough
temperature
of
the
domestic
hot
water.
As
domestic
hot
water
must
be
available
independent
of
ambient
conditions
the
temperature
in
this
tank
will
be
at
a
constant
state,
set
condensation.
Tank
2
is
also
used
as
a
storage
for
any
external
energy
sources
connected,
like
electric
heater,
oil
boilers
etc.
As
4
‐
way
mixing
valve
is
used
also
the
heating
system
can
use
energy
from
tank
2
if
the
energy
demand
to
heating
system
from
tank
1
exceeds
energy
supply
from
the
heat
pumps.
Tank
1
floating
condensation
(Heating)
Tank
2
set
condensation
(DHW)
Heat
pumps
RAD
Heat
pumps
The
heat
pumps
operate
in
a
special
way
in
order
to
supply
correct
temperature
to
the
tanks
at
all
times.
This
is
called
the
VFC
‐
technology
and
means
that
the
heat
carrier
flow
is
controlled
by
controlling
a
variable
speed
circulation
pump.
By
controlling
the
flow
also
the
flow
temperature
can
be
controlled
and
unlike
standard
systems,
high
temperature
water
can
be
supplied
also
with
low
return
temperatures
to
the
heat
pumps.