XV.
DESUPERHEATER
(OPTIONAL)
A
GeoSource 2000 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
supplemental
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 of the 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 coonections 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 l/2-nch type L copper tubing.
This tubing can be connected to the
hot water
tank
in
two
ways:
cNote:
GH98l's and GH1201's do not have a factory
installed
desuperheater
pump.
An external
pump,
such as
a Grundfos
IUPL5-42
is required.
METHOD 1
Using a desuperheater tee installed in the drain at the
bottom ofthe water heater
(See
Figure 7).
This is
the
preferred
method for ease of installation, 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
water
pipes.
METHOD 2
Taking hot water
from
the bottom drain and
retwning
it
to the cold water supply line
(See
Figure
8).
This method
maintains the same comfort
and efficiency levels but
increases
installation
time and costs.
This method
requires a check
valve in the return line to the cold water
supply
to
prevent
water from flowing backwards
through
the desuperheater
when the
tank
is filling. Water
passing
through 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
i/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-ll2'nches 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,tUffON: 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 enffance
with scale
or
buildup
from the bottom of the tank, restricting
water
flow. 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
ofdesuperheater
effectiveness. This may require
periodic
cleaning with Iron 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.
L
19
{-*
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