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520HN
Tankless Water Heater
Overview and Certifi cations
Engineering
Submittal
Sheet
LOW-LEAD
U
P
C
®
®
Engineering Specifi cations
Water heater shall be a Model Therm 520 HN NG or 520 HN LP.
Installation shall consist of ___Model Therm 520 HN NG and ___
Model Therm 520 HN LP tankless water heaters as manufactured
by Bosch. Heater shall be CSA listed for the USA and Canada to
the current version of standard ANSI Z21.10 / CSA 4.9. Heater
shall have an input of 117,000 BTU/hr with a gross output of
91,525 BTU/hr when fi red with natural gas or propane. Heater
shall operate on natural gas or propane with an AHRI certifi ed
performance energy factor of 0.78 and a thermal effi ciency of
80%. Tankless water heater shall have a recovery of 145 gallons
per hour at a 77°F temperature rise.
CONSTRUCTION
Water heater shall be of gas fi red, tankless design with a
modulating gas valve and hydro-power generated ignition system
allowing the water heater to operate without standing pilot, an
electrical connection, or battery. Burner shall be capable of 4:1
turndown of fi ring, without loss of combustion effi ciency. Heat
exchanger/combustion chamber shall incorporate a multi pass
copper tube and fi n design. Heat exchanger shall be rated for
C
Massachusetts
Plumbing Board
Approved
maximum working pressure not less than 150 psig. Vent shall
use 5” diameter galvanized B-vent material.
INSTALLATION
All aspects of installation of Water Heater Plant shall be in
strict accordance with manufacturer’s instructions. Materials
shall conform to all manufacturer’s recommendations including
a manufacturer listed vent system.
Water heater plant piping shall be fi eld constructed of
materials as specifi ed. Water heater shall be installed
with individually isolating shutoff valves for service and
maintenance, and a hot water hose connection for fi eld
testing. Unit shall have an ASME approved temperature/
pressure relief valve with a setting of 150 psig. Water heater
shall require a minimum gas pressure of 4.7“ W.C. (Natural
Gas) at 1,000 scfh (full load rated capacity). The water heater
shall be provided with an individual supply gas regulator for
proper gas regulation with a 3/4” NPT connection.
US
1 of 4
Bosch Thermotechnology Corp. reserves the right to make changes without notice due
to continuing engineering and technological advances |
BTC 746008303 B | 10.2014
Bosch Thermotechnology Corp.
Londonderry, NH • Ft. Lauderdale, FL
Tel: 1-866-642-3198 Fax: 1-603-965-7581 www.bosch-climate.us
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520HN
Tankless Water Heater
Engineering Specifi cations
Engineering Submittal Sheet
MODE OF OPERATION
Control of discharge water temperature shall be set through a dial at
the front of the unit with a fi eld adjustment from high to low.
WARRANTY
The heat exchangers shall carry a 15-year limited warranty against
leakage due to defects in materials or workmanship or corrosion
Dimensions and Connections
A
C
B
in a residential, non-direct recirculation system, subject to
the manufacturer’s water quality requirements. All other parts
and components shall carry a 2 year limited warranty against
defects in materials or workmanship.
L
K
G
F
E
D
Front view
Dimensions
Unit A B C D E F G H I J K L
Value Inches 16.73 25.75 13.15 5.11 21.25 2.55
2 of 4
Bosch Thermotechnology Corp. reserves the right to make changes without notice due
to continuing engineering and technological advances |
BTC 746008303 B | 10.2014
J
H
I
Side view
1.18
1.97 3.82 2.50 4.92 8.66
Bosch Thermotechnology Corp.
Londonderry, NH • Ft. Lauderdale, FL
Tel: 1-866-642-3198 Fax: 1-603-965-7581 www.bosch-climate.us
Page 3
Engineering Submittal Sheet
520HN
Tankless Water Heater
Performance Data
Unit Value
Maximum gas input BTU
Maximum output BTU 91,525
Minimum output BTU 23,906
Thermal effi ciency %
Operational Data
Unit Value
520 HN NG / Natural Gas - part number −
520 HN LP / Liquid Propane - part number − 7703431996
Weight lbs 35
Min. Inlet gas pressure NG / LP Inch W.C. 5.7 / 10.5
Max. Inlet gas pressure NG / LP Inch W.C. 14
Max. Working pressure psi 150
Min. Working pressure psi 30
Min. Activation rate GPM 0.5
Relief valve pressure rating psi 150
Venting category − I
Approved vent pipe material
−
117,000
7703331994
5 inch diameter double
wall Type B gas vent
80
Water Heating Capacity Curve
11
10
9
8
7
Flow
6
Rate
(GPM)
5
4
3
2
1
0
10 20 30 40 50 60 70 80 90
Temperature rise (°F)
3 of 4
Bosch Thermotechnology Corp. reserves the right to make changes without notice due
to continuing engineering and technological advances |
BTC 746008303 B | 10.2014
Water Heating Capacity Data
100
Temperature
Rise °F
35 5.2
45 4.1
55 3.3
65 2.8
75 2.4
90 2.0
Flow Rate GPM
Bosch Thermotechnology Corp.
Londonderry, NH • Ft. Lauderdale, FL
Tel: 1-866-642-3198 Fax: 1-603-965-7581 www.bosch-climate.us
Page 4
520HN
Tankless Water Heater
Clearances
Engineering Submittal Sheet
W1
W2
Top View Front View
Tankless Components
W5
W1
W3
W4
W1
Description Unit
Side clearance W1 Inch 4
Front clearance W2 Inch 4
Top clearance W3 Inch 12
Floor clearance W4 Inch 12
Rear clearance W5 Inch 0
Minimum
clearance
4 of 4
Bosch Thermotechnology Corp. reserves the right to make changes without notice due
to continuing engineering and technological advances |
BTC 746008303 B | 10.2014
Components Legend
1 Pilot burner
2 On/off button
3 Ignition unit
4 Power adjustment knob
5 Flexible hot outlet
6 Heat exchanger
7 Burner
8 Flow control knob
9 Water valve
10 Flexible cold inlet
11 Gas connection
12 Flue gas limiter
13 Exhaust outlet
Bosch Thermotechnology Corp.
Londonderry, NH • Ft. Lauderdale, FL
Tel: 1-866-642-3198 Fax: 1-603-965-7581 www.bosch-climate.us
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