Building Heat; Transformer - Econar GeoSource Invision 3 Q Series Installation And Operating Instructions Manual

1. Closed
Loop
Systems
Closed loop systems use
a
heat exchanger
of high density
polyethylene pipe buried underground
to
supply
a
tempered water solution back to the heat
pump.
Closed
loops
operate at
higher
flow
rates than open loops since
the
entering water temperature
(EWT)
is
lower.
The
loop
EWT
supplied to the heat
pump
has a
great effect on the
capacity
of
the
unit in
the
heating
mode. Earth loops in
cold climates are
normally sized
to
supply
a
wintertime
EWT to the heat
pump from
32oF
down to 25oF,
which
minimizes
the
installation cost of the earth
loop
and
still
maintains proper
system
operation. The
unit GPM
requirements
and pressure drops
for
loop pump sizing
is
available in Table
2.
Due to
the
effect
of loop water temperature on heating
capacity in the domestic hot water
(-DHW
and
-DWR)
modes, a
loop temperature
restriction is applied to these
DHW
applications.
If
earth
loop
temperatures exceed
80oF,
the
DHW
compressor's capacity
will
increase
to
the
point of
overloading the
DHW
condenser
coil. This
will
result
in high-pressure
lockout of
the
DHW mode.
If
heat
pump installations
are
expected to reach the 80oF
earth
loop
temperature mark, extra consideration
will
have
to
be
given to lowering the head pressure
by reducing earth
loop
flow,
increasing earth
loop
length, increasing
DHW
loop
flow, or reducing
DHW
output temperature.
When selecting the heat
pump,
choose a
unit that
will
supply the necessary
heating or
cooling capacity at the
minimum
and
maximum earth
loop temperature
conditions
respectively. Example;
if
a
residential system
requires 60,000
Btu/tr
to
heat
a
house
on an earth
loop
system (designed
for
32oF
minimum wintertime EWT),
and
40,000
Ba/tr
to cool
the house
on an earth
loop
(designed for
70oF
summertime
EV/T),
a
Qi8kW6T
GeoSource
Invisionr
heat
pump
is
required.
2.Open Loop
Systems
On
an open
loop
system the
design water temperature
will
be the
well
water temporature
in
your geogmphic region.
Many cold climates are
in the
50oF
range
for well
water
temperature.
Flow
rate
requirements
(in GPM)
and
unit
water-side pressure
drops (in PSI)
at 50oF
EWI
are
available
in
Table
2. If
your well water temperatures are
lower than
50oF,
for
instance Canadian
well water can be
as
low
as
43oF, the
flow rate must
be increased
to avoid
leaving water temperatures
below the
freezing
point.
If
well
water temperatures are above 50oF, as
in
some
southem states
where
well
water temperatures are above
70oF, the
flow
rates
may need to be increased
to dump
heat
more
efficiently in
the
cooling
mode.
Varying well water temperatures
will
have
little effect on
unit capacity
in
the
cooling mode (since the
well is
connected
to
the heat
pump
condenser),
but
can
have
large effects on
the
capacity
in
the
heating mode (since
the
well
is connected
to
the
evaporator).
If
well water
temperatures are to exceed 70oF, special
considerations,
such as
closed
loop systems, should be addressed'
10
B.
Building
Heat Loss/fleat Gain
The
space
load
must be
estimated accurately
for
any
successful
HVAC
installation. There
are
many guides or
computer programs available
for
load estimation
includhg fte ECONAR
GeoSource
Heat Pump
Handbook, Manual
J, and
others. After
the heat loss/heat
gain is completed and loop
EWT are established, the heat
pump
can
now be selected
using the specifications data.
Choose the capacity
of the heat
pump
based on
both
heating and
cooling load.
VII.
ELECTRICAL SERVICE
The main electrical service must be
protected by
a
fuse
or
circuit breaker, and be capable
of providing
the amperes
required by
the
unit
at
nameplate
voltage.
All
wiring
shall
comply with
the
national electrical code
and/or
any
local
codes
that may
apply.
Access
to
the
line
voltage
contactor is gained through the
knockouts provided on
either side
of the heat
pump next to
the
front corner.
Route
EMT
or
flexible
conduit
with appropriate 3-
conductor
wire to
the
contactor.
9WARNING - The
unit
must be
nroperlv erounded!9
When supplying power to external water pumps with
the
heat
pump's power supply,
use
only
impedance protected
motors. ECONAR PumpPAKsrM can be wired
directly to
the contactor
in
the
electrical
box.
The relay
will
energize
the
PumpPAKrM
with
a
call for heating or
cooling.
The
use
of
impedance
protected pumps eliminates the need
for
additional
fusing
on the
PumpPAKrM.
VIII.}4YOLT
CONTROL
CIRCUIT
The
wiring diagrams
in
Figures 7
and 8
show the
low
voltage controls
of
the heat
pump. This
section
will
break
down the three
basic components of the
low
voltage
circuit; transformer, thermostat,
and
controller.
A. Transformer
Electrical
diagrams
are
provided in Figures 7 and
8, and
on the
electrical box cover panel of
the heat
pump. An
internal 24-volt,75
VA
transformer
is
provided to
operate
all control features
of
the heat
pump.
Even though
these
ffansformers are
larger than the
industry
standard
40
VA
ffansformer, they
can
still
be overloaded
quickly
when
using
it for control
equipment
like
zone
valves. Table
3
shows the
transformer usage
for
GeoSource
Invision3
heat pumps.
If
any system's extemal controls require more
than
the
VA
available for external
use
from the transformer,
a
separate
transformer
must be used. The heat
pump's
transformer
can
generally power simple external
control