Baseboard Heatiag; Other Applications; Unit Sizing; Ground Sources And Design Water Temperatures - Econar GeoSource Ultra 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
115oF maximum hydronic
LWT to
maintain efficiency.
Standard
3/4" frmed
tube
baseboard conductors
have
approximately 200 Btuh/ft at
115oF
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
Btuh/square
inch at
a
115"F
hydronic
LWT,
they
work well with
geothermal
systems.
Although
the radiator may be rated
at
130oF,
the
system
could
still
operate
at the maximum
l15oF
LWT of
the
water-to-
water
heat
pump.
D. Other
Applications
Open loop applications such
as
outdoor swimming pools,
hot
fubs, 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
nickeUstainless
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.
e'Note:
Expect the operating temperature
of
an
indirect
coupled application to be
10oF
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.
IIT.
UNIT
SIZTNG
Selecting the
unit
capacity
of
a
hydronic geothermal
heat
pump requires
four
things:
A)
Building
Heat
Loss
/
Heat Gain.
B)
Ground
Sources and
Design Water
Temperatures.
C)
Hydronic-Side
Operating Temperatures.
D)
Temperature 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 Specffications. Choose
the
capacity
of
the
heat
pump
based on both heating
and
cooling
loads.
B.
Ground-Sources and Design Water
Temperatures
Ground
sources
hclude the
Ground
Water (typically
a
well)
and
the
Ground
Loop
varieties. Water
flow-rate
requirements vary
based
on
configuration. 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 offreeze
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.
"'Not
recommended for Cround
Water application.
Table
3
- Heat Exchanger
Pressure
Differential
(dP)
Correction Factors for
Freeze
Protection
Gffr(r)
50% GTF
120F
1257o
t23% N/a N/a
Propylene
Glyco1
2O7o
I
SuF
1367o
1337c
178Va
1t4%
25Vo 150F
145Vo 142Vo
N/a N/a
GTF =
GeoThermal Transfer
Flfid.6O%
water,4OTo
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
ground water
systems because the loop
Entering
Water
Temperature
(ESff)
is
lower. EWT
affects
the
capacity
of
the
unit in
the
heating mode,
and loops
in cold
climates
,f
4
GW37
8
5.s
4
1.3
GW47
11
5.2
6 1.6
GW57
13
6.0
9 3.1
GW77
15
7.9
il
4.6
GW87
3.5
2.5
GW240
60
4.3
N/a(')
50"T'Ground Waler
Series
Flow
(gprn)
dP*
.(psie)
trlow
(gpm)
d?*
(psig)
20
12
Anti-
Freeze
Percent
Volume
Freeze
Level
zs"l
l
35"F
90"F 110'F