Econar GeoSource Invision 3 Q Series Installation And Operating Instructions Manual page 5

earth
loop water temperatures.
Typical electric hot water
heaters
supply
16,720
Btu/hr (4.9
kwhr)
of
capacity.
The
heat
pump
heats the
DHW
by
circulating the water
from the
storage
tank through
a
double-walled,
refrigerant-to-water
condenser
coil.
When
the
temperature
of the water
in
the
storage
tank drops below a
reset
point of
113"F,
a
pump, built into
the heat
pump,
circulates the
water
and the
number
two
compressor
starts.
The compressor continues to run, heating
the
DHW,
until
the
water reaches
1l9oF.
The
DHW
pump
is
controlled
to
run continuously
only
when the compressor
is activated
in
DHW
mode.
This pump
will
also run
for
a
one
minute sampling period every
seven
minutes to
continuously
sample the
tank's water temperature
and
bring the
compressor on
at the
correct times. The tank
temperature is
controlled with
a
simple temperature
sensor
mounted on
a
copper pipe inside
the heat
pump.
The minimum entering water temperature on the
DHW
side (water
in
the storage
tank) is 50oF. Startup on
the
system
with colder water
will
require restricting
flow
to
the
unit until tank
temperatures
rise. A maximum
DHW
tank temperature
of
126oF
is also specified to keep the
system
from locking
out
on
high head pressure. Figure 4
shows the
required
plumbing
to connect
the system.
Figure 5
shows an
example of
a
plumbing circuit for
a
-DWR
unit that
has enough capacity
for
both domestic
hot water
and
radiant
floor
heating.
Figure 6
shows a
plumbing circuit for
a -DWR
unit
that is
sized
to
full
capacity
for
radiant
floor
heating. With this
setup, the
-DWR
unit
can
provide
supplemental domestic hot water
to an additional water
heater when
the
radiant
floor
is
not
utilizing
the
full load.
Reduced
flow
rates and increased
leaving water
temperatures can lock
the
DHW
circuit out
on
rhe
high
pressure switch,
so
follow
the
plumbing
dia-eram closely.
of 30 gallons is required;
normally
a
50
to
80
gallon tank
would
be used.
When installing
a
GeoSource
Invision3 with
the
-DWR
option,
use
an
indirectly fired water heater
as a storage
tank (shown in Figures 5
and
6).
The electric
elements can be
left in
and
wired
to
provide
backup water heating
ability,
but be sure to leave the
circuit breaker
off
during normal operation,
so
that
it
does
not interfere
with
tank temperatures.
€Note:
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
ener-qy
loss
to
the
floor.
Always
check
local
codes to be sure hot water tanks can
be used
for this purpose.
2.
DHW Pump
The
DHW pump
transfers the energy supplied by
the
GeoSource
Invision'heat
pump to the
storage
tank. This
pump is impedance protected
and does not require
additional
fusing. A
two-amp
inline
fuse is supplied on
the
pump
for additional safety
and
for
use
as
a shut
off
switch.
This pump
has been sized to
provide
the
required
flow
to
the heat
exchanger with
a
total
system pressure
drop
of
2
1
feet
ofhead.
This pressure drop
can be calculated from
the total pressure drop through *re piping,
added to the
pressure drop of
the heat
pump of
15
feet of head.
Figure
3
shows the
pump curve
of
the
DHW
pump.
The pump
can
provide
8
GPM
at
2l
feetof
head.
Using
one
inch
copper pipe is critical
to maintain
the
proper flow.
The
remaining six feet of
head is equivalent to
100 feet of
one
inch type
L
copper tubing or
a
combination of
straight
pipe
and
fittings. If
extremely long
distances separate the
heat
pump
and storage tank, or
ifadditional
pressure
drop
cannot
be avoided,
a
booster pump must
be added to
the
plumbing system. For
the
most efficient
operation, locate
the heat
pump
and storage
tank
as
close together
as
possible
and insulate all water piping.
A
common problem
with circulator
pumps is trapped
air
in
the
system.
This air accumulates
in
the
suction port
of
the
circulator
pump,
causing cavitation in
the
pump.
The
cavitation
can stop
the
flow of
water
and
leadio
premature pump
failure
and noisy operation.
The air
can
be eliminated by completely
purging
the system or by
placing
an air
separator
in
the
plumbing
lines.
The entire
system must
be
purged
of
air during initial
installation. Normal
systems
will
operate
on
iater
supply
pressure,
which
keeps air
from
reentering
the system.
If
a
system is not working
on water supply
pressure,
maintain
110
to
30
psi static
pressure
to
keep air out of
the
loop.
Otherwise, corrosion, bacteria
growth,
or pump cavitation
may occur.
An
operating temperature
range for
the earth
loop
side
of
the heat
pump is also specified
as
follows:
-
20"F
(minimum for
heating)
-
100"F
(maximum for cooling)
-
80"F (maximum
for -DHW
and
-DWR option)
These
limits
have been established based
on efficiency
limitations
and safety pressure
switch limits
(50_psi low_
pressure
curout
and
580 psi high-pressure
cutout). DHW
operation is
limited to
80nF because at
this warm of
a
source temperature,
the
heating capacity
increases
to
the
point of
overloading
the water-cooled
condenser, tripping
the system
offon
high
head pressure.
eNote: After all plumbing
and
purging
of the circuit
is
complete;
MOVE DIp SWITCH
#4,
Iocated
on
the
controller,
to the ON position to
initiate DHW
operation. Allowing
the pump to run
dry
will
damage
the circulating
pump
and
overheat
the motor.
1. Storage Tanks
Insulated electric hot water
heaters are used
for
storage
tanks
for
the
DHW circuit of
the heat
pump.
A minimum
3