# Water Heater Sizing & Speci Cations; Sizing Tankless Water Heaters - Bosch C1210ES Applications Manual

Bosch greentherm & therm tankless water heaters

1 0 | THERM/GREENTHERM Tankless Water Heaters
6 Water Heater Sizing &
Speci cations
This section describes the water heaters available from
Bosch Thermotechnology Corp. and provides a general
overview to the speci cations of each particular model.
More detailed information is contained in the installation

### 6.1 Sizing tankless water heaters

Rule of thumb sizing
The tables below provide a general rule of thumb when
sizing for most residential applications. For commercial
applications or for a more detailed sizing method, use the
Sizing by Chart instructions below in conjunction with the
charts on the next page.
Sizing by Chart
f
Measure the flow rates at each fixture that will be
used simultaneously and add them together. If only
one application will be used at a time measure each
fixture and use the maximum flow rate observed.
f
Using a known volume container, record several fill
times. Perform the calculation below to determine the
flow rate (a one gallon fill time of 30 seconds is 2.0
gallons per minute (GPM):
Volume (gallons)
Flow rate (GPM) =
Fill time (sec)
Hot water ow rate at 120°F Set Point temperature
Model
77°
C 1210
ES /
9.8
ESC
C 1050
ES
8.5
C 950
ES
7.7
940 ES
/ ESO
7.7
830 ES
6.7
520 HN
/ PN
4.3
330 PN
2.7
Simultaneous Showers
Data subject to change
sec
x
60
min
72°
67°
8.8
8.0
7.6
6.9
6.9
6.2
6.9
6.2
6.0
5.4
3.8
3.5
2.4
2.2
Sink Faucet
WA
WA
MT
MT
OR
OR
ID
ID
WY
WY
NV
NV
UT
UT
CO
CO
CA
CA
NM
NM
AZ
AZ
Figure 2 Average ground water temperatures
f
Using a thermometer, measure the incoming water
temperature. For reference, see average ground water
temperature map. Subtract this temperature from
the desired hot water temperature to get the degree
rise. If the desired hot water temperature is 120F and
incoming temperature is 55F, the desired degree rise
is 65F.
EXAMPLE:
f
Required flow rate of 2.0 GPM at a 65ÝF rise.
f
Refer to the graphs on page 10.
f
Since the demand is above the 330 PN capacity, this
application would require a 520 HN/PN gas tankless
water heater.
Inlet temperature (°F)
62°
57°
52°
7.3
6.7
6.2
6.3
5.8
5.4
5.7
5.2
4.9
5.7
5.2
4.9
5.0
4.6
4.2
3.2
2.9
2.7
1.9
1.7
2.0
Applications Manual
ND
ND
MN
MN
NY
NY
WI
WI
MI
MI
SD
SD
PA
PA
IA
IA
NE
NE
OH
OH
IN
IN
IL
IL
VA
VA
WV
WV
KS
KS
KY
KY
MO
MO
NC
NC
TN
TN
SC
SC
OK
OK
AR
AR
GA
GA
MS
MS
AL
AL
TX
TX
LA
LA
FL
FL
47°
42°
5.8
5.4
5.0
4.7
4.5
4.2
4.5
4.2
4.0
3.7
2.5
2.3
1.6
1.5
Bosch Thermotechnology Corp.
ME
ME
VT
VT
NH
NH
H
RI
MA
MA
A A
CT
NJ
˚F
DE
77˚
MD
72˚
67˚
62˚
57˚
52˚
47˚
42˚
37˚
37°
5.1
4.4
4.0
4.0
3.5
2.2
1.4