Hydronic-Side System Design - Econar GeoSource 2000 GW Series Installation And Operating Instructions Manual

8.
Stop the pump, and let
the
solution
stand
for
about
15
minutes.
9.
Flush the solution
by
adding
a
fresh water supply
to
the
pail.
Flush until
the
leaving
water
is
c1ear.
Note
-
observe
local
codes
for disposal.
10.
Flush the entire heat
pump
system
with
water.
VI.
HYDRONIC.SIDE SYSTEM
DESTGN
This
section deals
with
some common practices
used
when coupling
the
ECONAR
GeoSource
2fi)0 hydronic
heat pumps
to
the
space
conditioning heat
exchanger.
There are
so many
possible applications
for
hydronic
systems
that they cannot
all
be
covered
in
this
text.
Hopefully
these ideas can
help
in
many
of your
system
designs.
eNote
-
Actual
systems
must be constructed to
all
appropriate codes and
according to
accepted
plumbing
practices. Always
use
copper pipe
on the
hydronic
side.
elmportant
-
Pressure/Temperature
ports
!gu!.!!
be
installed
in
the entering and
leaving hydronic lines of
the
heat
pump.
A. Storage Tanks
@Important
-
The
heat
pump must
be coupled
to
the
space
conditioning
system through a water storage tank.
elmportant
-
The guideline
for
the
total
fluid
storage
in
the system
is
l0
gallons
of fluid for
each ton
of
hydronic
heat
pump capacity
(example, 50 gallons minimum
for
a
5-ton
unit). Size the
stora-qe
tank
for
the
diflerence
between the amount of
fluid in
the smallest
hydronic loop
and what the
system
requires.
If
in
doubt, size the storage
tank
for
the total capacity
of
the heat
pump.
A
properly
sized
storage
tank
eliminates
many problems
with
multiple
zone
hydronic systems. These problems include
excessive
leaving water
temperature
if
a
single
zone
cannot dissipate heat
quickly
enough, and hydronic
flow
reduction through the heat
pump when only
one zone is
calling. This may occur
because
the
hydronic circulating
pump
is
normally sized
to
provide the
heat pump's
required
flow with all
zones calling.
In
applications that
use
multiple smaller
zones, storage tanks absorb
the
relatively large amount
of
energy supplied
by
the
heat
pump
in
order
to
provide longer run
times and
less
compressor cycling
for
the heat
pump.
Storage
tanks
also
serve
to
dispense
energy
in
small amounts so that
the
conditioned zones have
time
to
absorb
heat
without
requiring high
discharge water temperatures.
(The
only
instance where a
storage tanks
is not required is when
the
heat
pump is coupled to
a large heat exchanger containing
the recommended amount
of fluid
capable
of
absorbing
the entire capacity of
the heat
pump.)
Insulated water
heaters are commonly used
for
storage
tanks.
aNote
- Always
check local
codes
to
ensure
water
heaters
can be
used as storage tanks.
Using
the
electric
elements
in
the
tank
as a secondary heat source
to the heat
pump
is
appealing
in
some
applications,
but
special
8
Listing Agency Certifications may be required
by
many
local
codes.
Specially listed water heaters are
available.
While all hot
water tanks are insulated
on
the
top
and
sides, many
do not
have insulation
on the
bottom. An
insulated
pad
beneath uninsulated
tanks
will
reduce
energy
loss to
the
floor.
@Important
-
The hydronic
flow
into
the storage tank
(particularly
a water heater) must not be restricted.
If
the
water heater has an
internal diffuser
"dip
tube," cut
it off
at
approximately
l2
inches
into
the tank.
The tank
temperafure
can
be conffolled
with a
simple
Aquastat
or
a
setpoint
controller. The
setpoint
controller
senses
tank water temperature
and
outside air
temperature
to
increase
the tank
temperature
as the
outside air
becomes
colder. This control
scheme
provides
the
highest
heating efficiencies
by requiring
the
lowest possible water
temperature
to
heat
the
space. Setting the
optimal
design
temperatures
in
the
conlroller is difficult,
and
the
simple
Aquastat does have
its
advantages.
To
help
in
setpoint
control, the
following
equation
can
be used:
Reset
Ratio
=
Design Water Temp
- Indoor
Design Temp
Indoor
Design Temp - Outdoor Design Temp
B.
Hydronic
Side
Circulators
Hydronic circulator pumps transfer the
energy supplied
by
ECONAR's hydronic heat pumps
to
the
space
conditioning heat exchanger. Select
a
quiet
operating
pump with
the
ability to supply
the
required flow
rate at
the
system pressure
drop. The circulator
supplying
the
heat
pump must
be
placed in
the
water supply line into
the
unit to provide the
best
pump
performance. Individual
zone
circulators must
also be
placed in
the supply lines
of
the heat
exchangers
they
serve. These
pumps are
often
used as
the on/off control
mechanism
for the
zone they
supply
as
shown
in
Figure
4.
Zone valves are
also
commonly
used
for
this purpose using a corrrmon pump
(shown in
Figure
5).
eNote
-
Select a common
pump at the total
flow of
all
the
zones
and the highest
pressure drop
of
any
one
parallel zone. Small Grundfos pumps (230
Vac) should
be
used as
circulator pumps. These pumps are
impedance
protected and do not
require
additional fusing
if
powered
directly from
the heat
pump.
VCAUTION -
Never
operate
with
hydronic
flow
rates
less than specified.
Low flow
rates,
or no
flow,
may
cause
the unit
to
shut down
on a pressure
lockout or
may
cause
a freeze rupture
of
the heat exchanger.
Pumps
must be
sized
to provide
the required
flow to
a
heat
exchanger
at
its
corresponding pressure drop.
This
pressure drop can be calculated
from the total
pressure
drop
through
the piping, plus the
pressure drop
of
the
space
conditioning
heat exchanger, and
plus
the pressure
drop through the
heat
pump heat
exchanger.
Table
4
shows the
hydronic water-flow
requirements and pressure
drop (dP),
and
Table 3
shows the dP
multiplier for various
I