Baseboard Heating; Other Applications; Iil Unit Sizing; Building Heat Loss / Heat Gain - Econar GeoSource 2000 GW Series Installation And Operating Instructions Manual

C. Baseboard Heating
Another
application
of
hydronic heating
is
finned
tube
baseboard
heating.
This
is
the
same
tubing used
with
boilers with
the
major
difference
being that the discharge
temperature
of
a geothermal heat
pump is
much lower
than
a boiler. The heat pump
system
must
be
sized
at
1l5oF
maximum hydronic
LWT to
maintain efficiency.
Standard 314"
finned tube baseboard conductors
have
approimately
200
Btuh/ft at
1151F
hydronic
LWT.
There
have been
successful
installations using baseboard
as
supplemental
heating,
and many other factors
must
be
considered,
such
as sufficient perimeter area
in
the
conditioned space
to allow for
the
required amount
of
baseboard. Suppliers
of
baseboard
radiators can help
size
the amount
of
baseboard and
fluid
temperature required
for
specific applications.
Cast
iron
radiators have been used successfully. When
rated
for
an output
of
70
BtuhL/square
inch at
a
1
l5"F
hydronic
LWT,
they
work well with geothermal
systems.
Although the radiator may be rated
at
130"F,
the
system
could
still
operate
at the maximum
1
l5nF
LWT of
the
water-to-water
heat
pump.
D. Other
Applications
Open
loop applications such
as
outdoor swimming pools,
hot
tubs,
whirlpools, tank heating, etc. are
easily
sized
based
on heat exchanger operating temperature and
flow.
In
many
instances,
sizing the heat pump
to
these
applications comes down to recovery
time.
A
larger
heat
pump
(within
reason
to
avoid short cycling)
will
provide
faster
system recovery.
elmportant
- An intermediate nickeVstainless plate
heat
exchanger
(as
shown
in
Figure
1)
between the
heat
pump
hydronic
loop and the open
system
is
required when
corrosive
fluid is
used
in
the
open
loop;
especially
on
swimming pools
where
pH
imbalance
can
damage
the
heat
pump.
qNote:
Expect
the operating temperature
of
an
indirect coupled application to be
lOnF
below
the
LWT
of
the heat
pump.
Other forms
of
closed
loop
systems
such
as
indoor
swimming pools,
pretreated fresh
air
systems, snow melt
systems,
and
valance heating/cooling systems
are
also
very
common
with
hydronic
heat
pumps.
The
sizing
of
the
heat
pump
to
these systems
is
more precise,
and
information from
those system
manufacturers is required.
III.
UNIT SIZING
Selecting the
unit
capacity
of
a
hydronic geothermal
heat
pump requires four
things:
A)
Building Heat
Loss
/ Heat Galn.
B)
Ground Sources and
Design Water Temperatures.
C)
Hydronic-Side
Operating Temperatures.
D;
Temperarure Limitations
A. Building
Heat Loss lHeat Gain
The
space
load must
be
estimated accurately
for
any
successful
HVAC installation. There are many guides or
computer programs available for
estimating heat loss
and
gain, including the ECONAR
GeoSource
Heat
Pump
Handbook,
Manual J, and others.
After
the heat loss
and
gain
analysis
is
completed,
Entering Water Temperatures
(EWT's) are
established,
and
hydronic-side
heating
conditions are determined. The heat pump can
now
be
selected
using the hydronic
heat
pump
data
found
in
the
Engineering Specifications. Choose
the
capacity
of
the
heat
pump
based on
both heating
and
cooling loads.
B.
Ground-Sources and Design
Water
Temperatures
Ground sources
include the
Ground
Water (typically
a
well)
and
the
Ground
Loop
varieties. Water flow-rate
requirements
vary
based
on
confi-Euration. ECONAR's
Engineering Specifications
provide
capacities at
different
loop water
temperatures
and hydronic leaving
water
temperatures.
Note: Table 2
shows
the
water-flow (GPM)
requirements and water-flow pressure differential
(dP) for
the heat exchanger, and
Table 3 shows the dP
multiplier
for various levels of
freeze
protection.
Table
2
- Ground-Side
Flow
Rate
*
dP (psig)
heat
exchanger
pressure
drops
are
for pure water.
Note:
dP
values
are
for
standard
heat
exchanger
configurations.
Cupro
Nickel heat exchanger configurations for
Ground
Water applications have
higher
dP pressue drop.
(2)
Not
.""orn-"nded
for Ground Water application.
Table
3
- Heat Exchanger Pressure
Differential (dP)
Percent
Volume
Freeze
Level
-,Frl
IP
Mrl
3sT
GTF'(., 507o GTF
12nF
125%
123Vo
N/a N/a
Propylene
Glycol
20Vo
l gt'F
136Vo 133V0
1
187c l14Vc
257o 150F
145%
1427o
N/a N/a
GTF = GeoThermal Transfer F1fid.60Vo water,407c
methanol.
1.
Ground Loop
Systems
(see
Figure 2)
Loop
systems use
high-density polyethylene pipe
buried
underground
to supply a tempered water solution
back to
the heat
pump. Loops
operate at
higher
flow
rates than
Factors
for
4
dP*
(psig)
f,Iow
(gpm)
.dP*
(psig)
Flow
(gpm)
GW29
4.0
4
5.2
GW36
5.5 4
5.5
7.8
5
'7.8
GW42
GW52
11
5.2 6
GW59 6.0
9
4.8
GW67 7.0 10 4.7
GW98 22 3.8 N/a(')
GW120 26
4.5
N/a('l
78 8.3 GW380 N/a(z)
Series
5{1"1'Ground
Walcr
7
8
10
7.2
13
14
)
Anti-
Freeze