Introduction; Bosch Water Heating Models; Sizing Tankless Water Heaters - Bosch GWH 715 ES Applications Manual

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1 Introduction

The Bosch Applications Manual is intended to present some of the
most common applications of the Bosch line of tankless and point of
use water heaters. Application drawings are shown with both piping
and corresponding electrical schematics where applicable. Auxiliary
equipment depicted does not necessarily represent any one
manufacturer or specifi c model number. There are a wide variety of
techniques, practices and piping strategies possible when installing
water heating appliances. It is the responsibility of the installing
contractor to determine the most suitable arrangement for the
application.
Although this manual covers many common applications for our
products, system possibilities are virtually endless. Should you
encounter an application that is not covered in this manual or have
any questions regarding any of its content, we encourage you to
contact your local sales representative or us directly at Bosch Water
Heating.
This is not a substitute for any of the product's installation manuals.
All specifi cations subject to change.
Installation must conform with local codes or, in the absence of
local codes, the National Fuel Gas Code ANSI Z 223.1/NFPA 54.
In Canada: Installation must conform with CGA B149.(1,2) INSTAL-
LATION CODES and/or local installation codes.

2 Bosch Water Heating Models

This section describes the water heaters available from Bosch
Thermotechnology Corporation. The information given in each
section provides a general overview to the specifi cations of that
particular model. More detailed information is contained in the
installation manuals. Download these manuals at www.BoschPro.
com.

2.1 Sizing tankless water heaters

Defi nitions
Major applications (2 GPM or more): Washing machine, bath tub,
shower nozzle
Minor applications(1.5 GPM or less): Low fl ow shower head,
bathroom sink, kitchen sink
Application manual | 11.2007
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 instructions below in
conjunction with the charts on the next page.
Sizing by Chart
Measure the fl ow rates at each fi xture that will be used
simultaneously and add them together. If only one application will
be used at a time measure each fi xture and use the maximum fl ow
rate observed.
Rule of Thumb Sizing
Model Number Number of Major
Applications
GWH 715 ES
GWH C 800 ES
GWH 425 HN/PN/EF
GWH 425 HN/PN/EF
GWH 260 PN
RP17PT
RP27PT
Using a known volume container, record several fi ll times. Per-
form the calculation below to determine the fl ow rate (a one
gallon fi ll time of 30 seconds is 2.0 gallons per minute (GPM):
Volume (gallons)
Flow rate (GPM) =
Fill time (sec)
Using a thermometer, measure the incoming water temperature.
Subtract this temperature from the desired hot water temperature
to get the degree rise. So, if the desired hot water temperature is
120F and incoming temperature is 55F, the desired degree rise is
65F.
This example requires a fl ow rate of 2.0 GPM at a 65˚F rise. Refer
to the graphs on the following page. Since the demand is above
the GWH 260 PN capacity, this application would require a GWH
425 HN/PN/EF gas tankless water heater. The electrical model
used for this application would be the RP27PT electric tankless
water heater.
BOSCH THERMOTECHNOLOGY CORPORATION
Applications manual
Number of Minor
Applications
2 0
2 1
1 1
0 2
1 0
1 0
1 1
sec
x
60
min