Bosch 520HN User Manual

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: [phone] Fax: [phone] www.bosch-climate.us

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: [phone] Fax: [phone] www.bosch-climate.us