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XVII.
DESUPERHEATER
(OPTIONAL)
A
GeoSource
DualTEK
unit
equipped
with
a
desuperheater can
provide
supplemental heating
of
a
home's
domestic hot
water.
This is
done
by
stripping
heat
from
the superheated
gas
leaving
the
compressor
and
transferring
it
to
a
hot water
tank. A
desuperheater
pump,
:
manufactured
into
the
unit,
circulates water
from
the
domestic hot water tank,
heats
it
using
a
double walled
water-to-refrigerant
heat
exchanger,
and
returns
it
to
the
tank.
The
desuperheater
provides
supp-lemental
heating
because
it
only
heats
water when
the
compressor
is
already
running to
heat
or
cool
the
conditioned
space.
Because the desuperheater
is
stripping
some
ofthe
energy
from
the heat
pump
in
order to
heat the
water,
the heat
pump's capacity
in
the
winter
will
be
slightly
less than
a
unit without
a
desuperheater.
During
extremely
cold
weather, or
if
the heat
pump cannot
keep
up
with
heating
the space, the desuperheater
fuse may
be
pulled
in
order
to
get
more capacity out
of
the
unit.
Insulated copper
tubing
should
be used
to run
from
the
hot water tank to
the desuperheater
connections
on the
left
side
of
the
unit.
The
built
in
desuperheater
pump
can
provide
the
proper
flow
to
the desuperheater
if
the
total
equivalent length
of
straight pipe
and
connections is kept
to
a
maximum
of
90
feet
of ll2-inch
type
L
copper tubing.
This
tubing
can
be connected
to
the
hot water tank
in two
ways:
METHOD
1
Using
a
desuperheater
tee
installed
in
the
drain
at
the
bottom of
the
water heater
(See
Figure
10).
This
is
the
preferred method
for
ease
ofinstallation, comfort
and
efficiency.
The
tee
eliminates
the need
to tap
into
the
domestic hot water lines
and
eliminates household water
supply temperature variations that could occur
from
connecting to
the
hot
waler
pipes.
METHOD
2
Taking hot
water
from
the
bottom
drain
and
returning
it
to
the
cold water supply
line
(See
Figure
71).
This
method maintains the
same
comfort
and
efficiency
levels
but
increases
installation time
and
costs.
This method
requires
a
check valve
in
the
retum line
to
the
cold
water
supply
to
prevent water
from flowing
backwards through
the desuperheater
when
the
tank is
filling.
Water
passing
though
the
pump backwards
damages the
rotor's bearing,
which
reduces
pump
life
and causes noise
problems
in
the
pump. A
spring-type check valve
with
a
pressure
rating
of
1/2
psi
or
less
is
recommended.
All
air must
be
purged
from
the desuperheater
plumbing
before
the
pump is engaged.
To
purge small
amounts
of
air
from
the
lines, loosen
the desuperheater
pump
from
its
housing by
turning
the brass
collar.
Let
water
drip
out
of
the
housing
until
flow
is
established,
and
re-tighten
the
brass
collar.
Using
l/2-inch
copper tubing
from
the
tank
to
the desuperheater
inlet
is
recommended to
keep
water
velocities high,
avoiding
air pockets
at the
pump
inlet.
An
air vent
in
the
inlet line
can also
help
systems
where
air is
a
problem.
If
one is used (we
recommend
a
Watts
Regulator brand
FV-4 or
Spirovent) mount
it
near the
desuperheater
inlet roughly
2-l/2
inches above the
horizontal
pipe.
Shutoffvalves allow
access
to
the
desuperheater
plumbing without
draining
the
hot water
tank.
Keep valves
open
when pump
is
running.
VC,LUttON:
Running
the desuperheater
pump
without
water
flow
will
damage the
pump.
Poor water
quality
may restrict
the
effectiveness
of
using
the desuperheater tee
by
plugging
the entrance
with
scale
or
buildup from
the
bottom
of
the
tank,
restricting
water
fl
ow.
Desuperheater
maintenance includes
periodically
opening
the
drain
on the
hot water tank
to
remove
deposits.
Ifhard
water,
scale,
orbuildup
causes
regular
problems
in
hot water
tanks
in
your
area,
it
may result
in
a
loss
of
desuperheater
effectiveness.
This
may require
periodic
cleaning
with
kon
Out
or similar
products.
The
desuperheater's
high temperature cutout switch is
located on
the
return
line from
the
water
heater.
The
switch is
wired in
series
with
the desuperheater
pump to
disable
the
pump
from circulating
at
entering water
temperature above 140oF.
Ifthe
desuperheater
causes
tank temperatures
to become
uncomfortably
hot, this
temperature switch
can be
moved to
the
leaving water
line
which
will
reduce the
tank
maximum
temperatures
10oF
to
15oF. Do not remove
the
high temperature switch
or
tank
temperatures
could
become
dangerously high.
A
fuse
is
attached to
the
fuseholder and must
be
inserted
in
the
fuseholder
after
the desuperheater
is
operational.
Do not insert fuse
until
water
flow
is
available or
the
pump
may
be damaged. Remove
the
fuse
to disable
the
pump
if
the desuperheater
isn't in
operation.
21
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