ProTankless GWH 715 ES

82% thermal efficiency .82 energy factor Direct vent, room-sealed combustion Vents vertically or horizontally with 3" stainless steel (AL29-4C) Ability to cascade units for increased flow rates Outdoor installation using optional kit Suitable for recirculating applications Available in natural gas (NG) or liquid propane (LP) 15-year warranty
Versatility and Dependability
Qualifies for $300 U.S. Federal Tax Credit
The GWH 715 ES will meet the demands of a busy household and can be installed almost anywhere. Our new generation of tankless water heaters offer higher flow rates, recirculation capabilities, sealed combustion, vertical or horizontal venting and an outdoor installation option.
GWH 715 ES Technical Specifications
Natural Gas: 199,000 BTU/Hr LP Gas: 199,000 BTU/Hr 0.65 gallons per minute (gpm) 35F rise @ 9.2 gpm 45F rise @ 7.2 gpm 55F rise @ 5.9 gpm 65F rise @ 5.0 gpm 77F rise @ 4.2 gpm 90F rise @ 3.6 gpm NG:.81 LP:.82 NG: 82+% LP: 82+% 30.5" h x 17.875" w x 11.25" d 67 lbs. Min. Firing Rate: 19,900 BTU/Hr Max. Firing Rate: 199,000 BTU/Hr Electronic Horizontal Vent Kit (#4TWHVK3S) Outdoor Kit (#PTOK) Wireless Remote (#TSTAT2) Tankless Link Cascading Kit (#TLINK)
Solid Copper Heat Exchanger
Primary Fan (Mixer) Secondary Air Fan LCD Display Control Unit
GWH 715 ES Installation Specifications
" Male NPT " Male NPT Minimum: 4" WC Maximum: 14" WC Minimum: 9" WC Maximum: 14" WC Minimum: 30 PSI (Well): 40 PSI Maximum: 150 PSI 120V (plugs in) 3" or 4" stainless steel (AL29-4C) Direct vent roomsealed combustion Installation Clearances Top: 12" Front: 1" Back: 0" Sides: 1" Floor: 12"
All information in both Technical and Installation Specification charts are for one GWH 715 ES.
Model GWH 715 ES Venting Configurations

3' M in.

Twin Pipe (Horizontal)

Twin Pipe (Vertical)

Horizontal Vent Kit required

Part # Part #

GWH 715 ES NG (Natural Gas) GWH 715 ES LP (Liquid Propane)
Ships complete with wall mounting bracket, pressure relief valve, built-in electronic temperature controls and equipped with 120V plug-in power cord. Refer to manual for condensate drain and venting requirements.
Bosch Group Bosch Water Heating 50 Wentworth Avenue Londonderry, NH 03053 Telephone: 866.642.3198 www.boschpro.com

77799101/1007

Applications manual
For tankless and point of use water heaters

Table of Contents

1 Introduction 2 Bosch Water Heating Models
2.1 Sizing tankless water heaters 2.2 Bosch GWH 715 ES 2.3 Bosch GWH C 800 ES 2.4 Outdoor Installation for GWH 715 ES and GWH C 800 ES 2.5 Bosch GWH 345 ESR 2.6 Bosch GWH 450 ESR 2.7 Bosch GWH 425 EF 2.8 Bosch GWH 425 HN 2.9 Bosch GWH 425 PN 2.10 Bosch GWH 260 PN 2.11 Powerstream Pro RP17PT, RP27PT 2.12 Powerstream Pro RP1P, RP2P, RP3P, RP7P, RP9P, RP12PT 2.13 Ariston Pro GL2.5Ti, GL4Ti, GL8Ti
3 Domestic Water Heating Applications
3.1 Point-of-use applications 3.2 Whole house applications
4 High Volume Potable Water Heating
4.1 Parallel unit applications 4.2 Cascade unit applications 4.3 External storage tank loading applications
5 Open Loop Space Heating
5.1 External storage tank 5.2 Indirect tank applications

6 Maintenance Drawings

6.1 Descaling procedure 6.1 Descaling procedure diagram
Application manual | 11.2007

Bosch Water Heating

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 specic 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 products installation manuals. All specications 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) INSTALLATION CODES and/or local installation codes.
2 Bosch Water Heating Models
This section describes the water heaters available from Bosch Water Heating. The information given in each section provides a general overview to the specications of that particular model. More detailed information is contained in the installation manuals. Download these manuals at www.BoschPro.com.
Applications manual | 11.2007
2.1 Sizing tankless water heaters
Denitions Major applications (2 GPM or more): Washing machine, bath tub, shower nozzle Minor applications(1.5 GPM or less): Low ow shower head, bathroom sink, kitchen sink 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 ow rates at each xture that will be used simultaneously and add them together. If only one application will be used at a time measure each xture and use the maximum ow rate observed.
Rule of Thumb Sizing Model Number GWH 715 ES GWH C 800 ES GWH 425 HN/PN/EF GWH 425 HN/PN/EF GWH 260 PN RP17PT RP27PT Number of Major Applications 1 Number of Minor Applications 1
Using a known volume container, record several ll times. Perform the calculation below to determine the ow rate (a one gallon ll time of 30 seconds is 2.0 gallons per minute (GPM):

Flow rate (GPM) =

Volume (gallons) x 60 sec min 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 ow rate of 2.0 GPM at a 65F rise. The data point is shown on each graph. 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.

GWH C ES GWH ES

GWH PN/HN GWH PN/HN

90 Degree rise (F)

Gas Appliance Sizing Chart

RP27PT P

RP17PT P
RP12PT P RP7P RP3P 3 RP1P P RP9P P9P

90 Degree rise

Electric Appliance Sizing Chart Note: Maximum flow rates dependant on site conditions

2.2 Bosch GWH 715 ES

Features: Electronic ignition and built in power vent 82% thermal efciency Vents vertically or horizontally with 3" or 4" stainless steel (AL294C) Direct vent room-sealed combustion Computerized temperature control ensures temperature stability Model GWH 715 ES N for natural gas (NG) supply Model GWH 715 ES L for liquid propane (LP) supply 15-year warranty Qualies for $300 tax credit GWH 715 ES Technical Specications Gas input Natural Gas: 19,900 - 199,000 BTU LP Gas: 19,900 - 199,000 BTU Minimum ow to activate Flow rates 0.65 gallons per minute (gpm) 45F 55F 65F 77F 90F rise rise rise rise rise @ @ @ @ @ 7.2 5.9 5.0 4.2 3.6 gpm gpm gpm gpm gpm

3ft minimum distance

GWH 715 ES Installation Clearances Top (A) Front (B) Back Sides Floor (C) 12" 1" 0" 1" 12"
Thermal Efciency Dimensions Weight Modulating gas valve Ignition Accessories
NG: 82% LP: 82% 30" h x 17" w x 11" d 67 lbs. yes Electronic Outdoor kit (PTOK) Wireless Remote (TSTAT2) Tankless Link Cascading Kit (TLINK) Freeze Prevention Kit (8700400022) Water Filter Kit (8703305356)
Fig. 1 Venting congurations
Installation guidelines: GWH 715 ES Installation Specications Gas connection Water connections NG gas pressure LP gas pressure Water pressure (Static) Electrical supply Venting " Male NPT " Male NPT Minimum: 4" W.C. Maximum: 14" W.C. Minimum: 9" W.C. Maximum: 14" W.C. Minimum: 30 PSI Minimum well pressure: 40 PSI Maximum: 150 PSI 120VAC - plugs in 3" or 4" stainless steel (AL29-4C) direct vent room-sealed combustion Venting: Must be 3" or 4" AL29-4C sealed stainless steel vent pipe. Slope horizontal runs up to termination " per foot. The last horizontal section of exhaust vent pipe between last elbow and termination must slope down to the termination " per foot. Do not combination vent with any other appliance. Install condensate drain where applicable. See manual for vent terminator clearances. Gas piping: Heater will not function properly without adequate supply gas pressure. Any appliance connector should be " minimum diameter Plumbing: Install the included pressure relief valve and pipe to suitable drain. Minimum piping diameter is ". Do not solder directly to the bottom of the unit. Use unions to facilitate easy future maintenance. Use full port ball valves for isolation valves. Partially ll condensate drain tube loop (where applicable) with water prior to start up.

2.3 Bosch GWH C 800 ES

Features: Electronic ignition and built in power vent Condensing technology with 92% thermal efciency Vents vertically or horizontally with 3" or 4" PVC, CPVC or ABS (Schedule 40) vent pipe. Direct vent room-sealed combustion with concentric venting option Computerized temperature control ensures temperature stability Model GWH C 800 ES N for natural gas (NG) supply Model GWH C 800 ES L for liquid propane (LP) supply 15-year warranty Qualies for $300 tax credit GWH C 800 ES Technical Specications Gas input Natural Gas: 19,900 - 199,000 BTU LP Gas: 19,900 - 199,000 BTU Minimum ow to activate Flow rates 0.65 gallons per minute (gpm) 45F 55F 65F 77F 90F rise rise rise rise rise @ @ @ @ @ 8.0 6.4 5.5 4.6 3.9 gpm gpm gpm gpm gpm

GWH 450 ESR Installation Specications Gas connection Water connections NG gas pressure LP gas pressure Electrical supply Venting " Male NPT " Male NPT Minimum: 5.5" W.C. Maximum: 14" W.C. Minimum: 11" W.C. Maximum: 14" W.C. 120VAC - plugs in 3" stainless steel (AL29-4C) direct vent room-sealed combustion

2.7 Bosch GWH 425 EF

Features: Electronic ignition and built in power vent Thermal efciency of 82% Vents with 4" stainless steel or galvanized vent pipe Specifically designed for horizontal vent terminations Modulating gas valve ensures temperature stability Model GWH 425 EF N for natural gas (NG) supply Model GWH 425 EF L for liquid propane (LP) supply 15-year warranty Qualies for $300 tax credit (LP only) GWH 425 EF Technical Specications Gas input Minimum ow to activate Maximum ow rates Thermal Efciency Dimensions Weight Modulating gas valve Ignition Natural Gas: 28,000 - 130,000 Btu/h LP Gas: 28,000- 125,000 Btu/h 0.5 gallons per minute (GPM) 4.6 gpm @ 45F rise NG: 80% 44 lbs. yes Electronic LP: 82%
29.75" h x 18.25" w x 8.75" d
Installation guidelines: Venting: 4" AL29-4C sealed stainless steel or 26 gauge galvanized vent pipe. Slope horizontal runs up to termination " per foot. Do not combination vent with any other appliance. See manual for vent terminator clearances. Gas piping: Heater will not function properly without adequate supply gas pressure. Any appliance connector should be " minimum diameter Plumbing: Install the included pressure relief valve and pipe to suitable drain. Minimum piping diameter is ". Do not solder directly to connections on the bottom of the unit. Use full port ball valves for isolation valves.
GWH 425 EF Installation Specications Gas connection Water connections NG gas pressure LP gas pressure Electrical supply Venting " Male NPT " Male NPT Minimum: 7" W.C. Maximum: 14" W.C. Minimum: 11" W.C. Maximum: 14" W.C. 120VAC - plugs in 4" stainless steel (AL29-4C) or 26 gauge galvanized
GWH 425 EF Installation Clearances Top (A) Front (B) Back Sides Floor (C) 12" 4" 0" 4" 12"

2.8 Bosch GWH 425 HN

Features: Hydro-generated ignition 80% thermal efciency Endless hot water for one major application at a time Venting: 5" double wall B-vent natural draft Modulating gas valve constant temperature at varying flow rates Model GWH 425 HN N for natural gas (NG) supply Model GWH 425 HN L for liquid propane (LP) supply 15-year warranty Qualies for $300 tax credit GWH 425 HN Technical Specications Gas input Natural Gas: 30,735 - 117,000 BTU LP Gas: 30,735 - 117,000 BTU Minimum ow to activate Flow rates 0.6 gallons per minute (gpm) 45F 55F 65F 77F 90F rise rise rise rise rise @ @ @ @ @ 4.2 3.4 2.9 2.4 2.1 gpm gpm gpm gpm gpm

LIS TE D VE NT C AP

GWH 425 HN Installation Clearances Top (A) Front (B) Back Sides Floor (C) 12" 4" 0" 4" 12"
NG: 80% LP: 80% 25.75" h x 16.75" w x 8.5" d 33 lbs. yes Hydro-generated Horizontal vent kit (AQ4) - power vent kit for horizontal venting
E S TA B LIS H A O NE F O O T R IS E B E F O R E A NY E LB O W S LIS TE D G AS VE NT

MINIMUM 6 FE E T (1.8M)

GWH 425 HN Installation Specications Gas connection Water connections NG gas pressure LP gas pressure Water pressure (Static) " Male NPT " Male NPT Minimum: 7" W.C. Maximum: 14" W.C. Minimum: 11" W.C. Maximum: 14" W.C. Minimum: 30 PSI Minimum well pressure: 40 PSI Maximum: 150 PSI 120VAC - plugs in 5" minimum diameter - natural draft AQ4 horizontal vent kit required for horizontal terminations
Fig. 2 Venting conguration
Installation guidelines: Venting: 5" minimum diameter do not reduce vent size Refer to installation manual for vent material options Do not combination vent with any power vented appliances Establish a one-foot rise before any elbows Minimum vent height - 6 feet Horizontal sections must slope upwards at least " for every foot of the horizontal length and be properly supported Gas piping: Heater will not function properly without adequate supply gas pressure Any appliance connector should be " minimum diameter Plumbing: Install the included pressure relief valve and pipe to suitable drain Minimum piping diameter is " Do not solder directly to connections on the bottom of the unit Use full port ball valves for isolation valves
Electrical supply Vertical venting Horizontal venting

2.9 Bosch GWH 425 PN

Features: Standing pilot ignition 78% thermal efciency Endless hot water for one major application at a time Modulating gas valve constant temperature at varying flow rates Model GWH 425 PN N for natural gas (NG) supply Model GWH 425 PN L for liquid propane (LP) supply 15-year warranty GWH 425 PN Installation Clearances Top (A) Front (B) Back Sides Floor (C) 12" 4" 0" 4" 12"
GWH 425 PN Technical Specications Power input Natural Gas: 31,000 - 117,000 BTU LP Gas: 31,000 - 117,000 BTU Minimum ow to activate Flow rates 0.6 gallons per minute (gpm) 45F 55F 65F 77F 90F rise rise rise rise rise @ @ @ @ @ 4.2 3.4 2.9 2.4 2.1 gpm gpm gpm gpm gpm
NG: 78% LP: 78% 25.75" h x 16.75" w x 8.5" d 33 lbs. yes Standing pilot Horizontal vent kit (AQ4) - power vent kit for horizontal venting
GWH 425 PN Installation Specications Gas connection Water connections NG gas pressure LP gas pressure Water pressure Electrical supply Vertical venting Horizontal venting " Male NPT " Male NPT Minimum: 7" W.C. Maximum: 14" W.C. Minimum: 11" W.C. Maximum: 14" W.C. Minimum: 30 PSI Maximum: 150 PSI 120VAC - plugs in 5" minimum diameter - natural draft AQ4 horizontal vent kit required for horizontal terminations

Features: Over 90% efciency rating 10-year warranty on heat exchanger Durable polymer construction External temperature control knob Thermal cut-out for safety Flow sensor to provide a constant output temperature Provides an ENDLESS supply of hot water Weighs less than 25 pounds and ts virtually anywhere No temperature/pressure relief valve necessary (unless required by local codes) Installation guidelines: Electrical: Minimum electrical service for RP17PT is 150 amps. Minimum electrical service for RP27PT is 200 amps. Minimum wire size for both models is 8 AWG. Plumbing: Do not solder directly to connections on the bottom of the unit. Use unions to facilitate easy future maintenance. Use full port ball valves for isolation valves.

RP17PT terminal block

Technical Specications Model Efciency Dimensions Weight Water ttings Activation rate Electrical requirements Volts Kilowatts Amps Wire size

U.S.A Canada U.S.A

RP17PT 90%
15 " x 15 " x 4 "

RP27PT 94%

20 lbs. " Male NPT 0.6 gpm 240 17.25kW 80 (2x40 amps) 80 (1x80 amps) 8 AWG
(4 conductors & ground)
22 lbs. " Male NPT 0.8 gpm 240 26.85kW 120 (3x40 amps) 120 (1x120amps) 8 AWG
2 independent 40 amp double-pole circuit breakers
Fig. 5 RP17PT Electrical Connections

Canada

Check Canadian Electrical Code (C22.1-02) Single 2.6 gpm 2.3 gpm 2.0 gpm 1.7 gpm 1.5 gpm
Check Canadian Electrical Code (C22.1-02) Single 4.0 gpm 3.7 gpm 3.0 gpm 2.6 gpm 2.2 gpm

RP27PT terminal block

Phase 45F Rise 50F Rise 60F Rise 70F Rise 80F Rise
Maximum ow rate at given temperature rise
3 independent 40 amp double-pole circuit breakers
Fig. 6 RP27PT Electrical Connections
2.12 Powerstream Pro RP1P, RP2P, RP3P, RP7P, RP9P,RP12PT
Installation guidelines: Features: 5-year warranty on heat exchanger Saves space Installs vertically or horizontally (Model RP12PT only installs horizontally) All models must be hardwired Solid copper heat exchanger, copper sheathed elements and tough plastic housing High/low kW settings possible within most models Model RP12PT has thermostatic adjustable control Electrical: Refer to the chart below as specication varies by model Plumbing: Do not solder directly to connections on the bottom of the unit. Use unions to facilitate easy future maintenance. Use full port ball valves for isolation valves.

Ariston Pro GL2.5 Ti Ariston Pro GL4 Ti

Symbols

Temperature and pressure relief valve Sink

Flow direction

Ariston Pro GL8 Ti

Service valve

Drain pan
Note: This drawing is conceptual in nature and does not address all design, installation or safety considerations. Additional safety and/or auxiliary equipment may be needed. This diagram is for reference use by officials, designers and licensed installers. It is expected that installers have adequate knowledge of accepted industry practices for the equipment, procedures, and applications involved. Drawing is not to scale.
Drawing # POU1 CN rev 06/06
3.1.2 Powerstream Pro electric point-of-use tankless water heater PowerstreamPro point-of-use water heaters come in four models to serve a wide range of applications. Finding the right model depends upon your desired temperature and ow rate. Use the table below to nd the model best suited to your customers needs. Flow controls and faucet aerators can greatly enhance performance. Note: Water heater must be lled with water and purged of air prior to supplying power.

cold supply hot

Powerstream Pro RP1P, RP2P, RP3P, RP7P, RP9P, RP12PT hot cold

cold supply

Powerstream Pro RP1P, RP2P, RP3P, RP7P, RP9P, RP12PT
Drawing # POU2 CN rev 06/07
3.1.3 Bosch GWH-260PN gas tankless water heater The Bosch GWH-260PN gas tankless water heater offers a compact and lightweight design for easy installation. This unit is equipped with standing pilot ignition and is intended for low volume applications.
Temperature and pressure relief valve

Bosch GWH 260 PN

Service valves

Low flow shower

Drawing # POU3 CN rev 06/07
3.2 Whole house applications
Whole house applications cover the typical home applications up to a 2 or 3 bedroom house. See the sizing guide (Section 2.1) to determine the best Bosch water heater model for your application. An enhanced design including an Ariston mini tank in line to the hot water source will reduce the wait time for hot water and improve temperature stability. 3.2.1 Powerstream Pro whole house applications The RP17PT and RP27PT must be hard wired directly to the breaker box.
Powerstream Pro RP17PT or RP27PT
Ariston Pro GL4Ti for pipe runs over 100 ft, use GL8Ti
Note: place Ariston close to the point of use to reduce wait time for hot water.

Hot Cold

Standard tub fixture
Note: Cold water piping to fixtures not shown for clarity purposes.
Drawing # WH1 CN rev 06/07
3.2.2 Powerstream Pro whole house application with domestic recirculation loop The circulator should be controlled by an external aquastat, or with a timer to run only during times of expected hot water usage.

Ariston Pro GL4Ti (for pipe runs over 100ft use GL8Ti)
Bronze circulator pump sized according to UPC standards
(Taco Bronze 007 or Grundfos 15-42B will cover most homes up to 3 bathrooms)

Flow check valve

Timer or Aquastat
Potable water expansion tank
Sink Standard tub fixture
Note: Cold water piping to fixtures not shown for clarity purposes. Note: This drawing is conceptual in nature and does to address all design, installation or safety considerations. Additional safety and/or auxiliary equipment may be needed. This diagram is for reference use by officials, designers and licensed installers. It is expected that installers have adequate knowledge of accepted industry practices for the equipment, procedures, and applications involved. Drawing is not to scale.
Drawing # WH1R CN rev 06/07
3.2.3 Bosch ProTankless gas water heater Below are two examples of Bosch ProTankless gas water heater installations for the whole house. One example shows an Ariston mini tank in line for reduced hot water wait time and increased temperature stability.

Bosch Bosch Bosch Bosch

GWH GWH GWH GWH
715 ES, C 800 ES, 425 HN or 425 PN

Pressure relief valve

Note: Cold water piping to fixtures not shown for clarity purposes. Note: This drawing is conceptual in nature and does not address all design, installation or safety considerations. Additional safety and/or auxiliary equipment may be needed. This diagram is for reference use by officials, designers and licensed installers. It is expected that installers have adequate knowledge of accepted industry practices for the equipment, procedures, and applications involved. Drawing is not to scale.
Drawing # WH2 CN revA 10/07
3.2.4 Bosch ProTankless gas water heater with domestic recirculation loop The circulator should be controlled by an external aquastat, or with a timer to run only during times of expected hot water usage.
Potable water expansion tank Flow check valve Pressure relief valve Sink Standard tub fixture

Bronze circulator sized according to UPC standards
Drawing # WH2R CN rev 06/07
Potable water Potable water is water that is suitable for drinking. Bosch Water Heating appliances are approved to heat potable water only. Heating any other liquid other than potable water will void the manfuctures warranty covering the appliance. Introduction This section lays out the options for high volume water heating for large residential and light commercial applications including continuous ows and high volume demands of large home and commercial applications.
4.1 Parallel unit applications
Parallel unit applications have twice the activation rate of single unit applications. The following designs are for continuous ow, high volume hot water needs. Not intended for residential use. To balance ows use reverse return piping. (shown below)
4.1.1 Bosch ProTankless gas water heater in parallel for commercial applications Two Bosch ProTankless units will have double the activation rate of a single unit. When sizing gas line, ensure the gas line is sized to carry the BTU load of two units plus any additional gas appliances. See the installation manuals for a gas line sizing chart.
Bosch GWH 715 ES, Bosch GWH C 800 ES,
*see text above about activation rate and gas supply requirements

Pressure relief valves

Drawing # P2 CN revA 10/07
4.2 Cascading unit applications
A cascading application should be considered if the potential hot water demand exceeds the capacity of one GWH 715 ES or GWH C 800 ES. The cascading set up supports variable ow inputs and is designed for large homes and commercial applications. 4.2.1 GWH 715 ES and GWH C 800 ES cascading Cascading allows up to two appliances to be connected in parallel. One of the appliances will serve as the controlling Master appliance and will attempt to meet the hot water demand. If the hot water demand is beyond the capacity of the Master appliance, a signal is sent to the Slave appliance to begin operation.
Bosch GWH 715 ES or Bosch GWH C 800 ES
The plumbing must be connected in the reverse return method with a minimum number of elbows to aid in balancing pressures between the two appliances. If a domestic recirculation system is desired, recirculate the water through the Ariston ProTi water heater as seen in chapter 3.4. Locate appliances close together for improved performance. Follow industry plumbing practices when installing multiple appliances Minimum pipe diameter: " Minimum water pressure: 50 psi Maximum distance between appliances: 36" Insulate pipes to prevent heat loss.
tankless link hot cold hot cold

outlet inlet

Ariston Pro GL8Ti recommended
Water hammer arrestor Service valves
Pressure relief valve Tankless link
Drawing # CA1 CN revA 10/07
4.3 External storage tank loading applications.
Introduction This section lays out tank loading options for high volume water heating for large residential and light commercial applications including continuous ows and high volume demands of large home and commercial applications.
4.3.1 GWH 345/450 ESR pressure drops and circulator guidelines The maximum amp draw for any circulator connected directly to the appliance must not exceed 1.5 amps Circulator should be sized by the professional plumbing contractor Bronze or stainless steel circulators required for all open loop applications

50 feet of head

40 feet of head

Inlet pressure

30 feet of head

GWH 345 ESR

20 feet of head

10 feet of head

0 feet of head 0 GPM

water flow rate

GWH 450 ESR

0 feet of head

0 GPM 1 GPM 2 GPM 3 GPM 4 GPM 5 GPM 6 GPM
Pressure drop curves Note : Flow above 6 GPM is not permitted.
4.3.2 Single unit tank loading application plumbing diagram The GWH 345/450 ESR is specically designed for this application.

Cold water DHW feed

Bosch GWH 345 ESR, Bosch GWH 450 ESR
Potable water expansion tank Pressure relief valve Flow direction External storage tank
12K ohm thermistor with immersion well
Note: Piping to fixtures not shown for clarity purposes. Note: This drawing is conceptual in nature and does not address all design, installation or safety considerations. Additional safety and/or auxiliary equipment may be needed. This diagram is for reference use by officials, designers and licensed installers. It is expected that installers have adequate knowledge of accepted industry practices for the equipment, procedures, and applications involved. Drawing is not to scale.
Drawing # STL CN revA 10/07
4.3.2 Single unit tank loading application electrical diagram The following shows the appropriate electrical connections for plumbing diagram 4.3.2

Terminal box

110VAC from outlet

ESR control board

Single Unit Tank Loading Electrical Diagram
Drawing # ESTL CN revA 10/07
5.1 External storage tank
Introduction This section is designed to provide a road map of techniques for using a tankless water heater to heat domestic water and at the same time provide space heating in residential applications. As with all installations, check with the local authority having jurisdiction. Some jurisdictions may not allow these types of applications. The appliances shown in this section are approved under ANSI Z21.10.3 and CSA 4.3 as circulating gas water heaters. Only open loop applications are approved under this standard. 5.1.1 Radiant space heating and DHW plumbing diagram

Cold water feed

Potable water expansion tank Flow direction Radiant piping Storage tank
Thermostatic mixing valve
Drawing # ROL CN revA 10/07
5.1.1 Radiant space heating and DHW electrical diagram The following shows the appropriate electrical connections for plumbing diagram 5.1.1

T Stat T Stat

24 VAC POWER

SR 502

FUSE 1 AMP

TWO ZONE SWITCHING RELAY

Neutral 120Vac
Radiant Space Heating and DHW Electrical Diagram
Drawing # EROL CN revA 10/07
5.1.2 Fan coil space heating and DHW plumbing diagram

Fan Coil

Potable water expansion tank Flow check valve Pressure relief valve Storage tank

Air seperator

Tank Aquastat
Note: Piping to fixtures not shown for clarity purposes. Note: This drawing is conceptual in nature and does to address all design, installation or safety considerations. Additional safety and/or auxiliary equipment may be needed. This diagram is for reference use by officials, designers and licensed installers. It is expected that installers have adequate knowledge of accepted industry practices for the equipment, procedures, and applications involved. Drawing is not to scale.
Drawing # FCOL CN revA 10/07
5.1.2 Fan Coil space heating and DHW electrical diagram The following shows the appropriate electrical connections for plumbing diagram 5.1.2

PE ESR control board

T Stat

SRZONE SWITCHING RELAY

R W T T

24 VAC COM

120 VAC INPUT

AQUASTAT

Fan Coil Space Heating and DHW Electrical Diagram
Drawing # EFCOL CN revA 10/07
5.1.3 Baseboard/ Radiant Panel space heating and DHW plumbing diagram
Potable water expansion tank Flow check valve Pressure relief valve Flow direction

Baseboard/ Radiant Panel

Storage tank
Thermostatic Mixing valve
Drawing # BB OL CN revA 10/07
5.1.3 Baseboard/Radiant Panel space heating and DHW electrical diagram The following shows the appropriate electrical connections for plumbing diagram 5.1.3

SR 503

or equivalent
ZONE1 ZONE2 ZONE3 THREE ZONE SWITCHING RELAY WITH OPTIONAL PRIORITY
Baseboard Space Heating and DHW Electrical Diagram

Note: This drawing is conceptual in nature and does not purport to address all design, installation or safety considerations. Additional safety and/or auxiliary equipment may be needed. This diagram is for reference use by officials, designers and licensed installers. It is expected that installers have adequate knowledge of accepted industry practices for the equipment, procedures, and applications involved. Drawing is not to scale.
Drawing # EBBOL CN revA 10/07
5.1.4 Baseboard/ Radiant Panel space heating and DHW (with Ariston mini tank) plumbing diagram
Aquastat well with 12k ohm thermistor (insulate piping around thermistor)
Ariston GL8Ti mini water tank Flow check valve Pressure relief valve Bronze circulator sized according to UPC standards Potable water expansion tank
Aquastat well & 12kohm thermistor Service valves
Drawing # BBAOL CN revA 10/07
5.1.4 Baseboard/Radiant Panel space heating and DHW (with Ariston mini tank) electrical diagram The following shows the appropriate electrical connections for plumbing diagram 5.1.4

Room Thermostat

Baseboard/Radiant Panel Space Heating and DHW (with Ariston mini tank) Electrical Diagram
Drawing # EBBAOL CN revA 10/07
5.1.5 Baseboard/ Radiant Panel space heating and DHW (without storage tank) plumbing diagram

Insulate piping

Piping Insulation Flow check valve Pressure relief valve Bronze circulator sized according to UPC standards Flow direction
Aquastat well & 12kohm thermistor
Drawing # BBNTOL CN revA 10/07
5.1.5 Baseboard/Radiant Panel space heating and DHW (without storage tank) electrical diagram The following shows the appropriate electrical connections for plumbing diagram 5.1.5
Baseboard/Radiant Panel Space Heating and DHW Without Storage Tank Electrical Diagram
5.2 Indirect Tank Applications
5.2.1 Indirect Baseboard/ Radiant Panel space heating and DHW plumbing diagram Note: Not suitable for space heating applications requiring high water temperature.

Cold feed

Potable water expansion tank Flow check valve Pressure relief valve Flow direction Indirect hot water tank

Pressure reducing valve

Back Flow preventer
Drawing # IDBBOL CN revA 10/07
5.2.1 Baseboard/Radiant Panel space heating and DHW electrical diagram The following shows the appropriate electrical connections for plumbing diagram 5.2.1
Indirect Baseboard/Radiant Panel Space Heating and DHW Electrical Diagram
Drawing # EID BBOL CN revA 10/07
Bosch appliances are designed to last for many years. In order to keep the heater operating properly, periodic maintenance is required. Please consult the installation manual for maintenance intervals. A descaling procedure drawing is included to assist in clearing the water heater of mineral deposits that may build up over time.

6.1 Descaling procedure

This procedure should only be done if there is evidence of scale build-up such as a reduced hot water ow rate or if the water is known to have high levels of minerals such as calcium. 1. Disconnect electrical supply from the water heater. 2. Shut off the water supply to the water heater using (installer supplied) isolation valve. 3. Open hot water taps to drain and relieve pressure from the plumbing system. 4. Drain water from the units heat exchanger by disconnecting inlet and outlet water connections. 5. Connect the line (A) from the outlet of the circulating pump (installer supplied) to the inlet water tting on the water heater. 6. Using another line (B), connect to the water outlet tting on the water heater. Route the other end of this line into a descaling reservoir. 7. Using a 3rd line (C) from the descaling reservoir, connect to the inlet side of circulating pump. Verify there is a lter on the end of the line in the descaling reservoir. 8. Make sure all connections are hand tight. 9. Fill tank with descaling solution so lines inside are submersed. We recommend a straight white vinegar. If using a commercial descalant, refer to manufacturers instructions for proper dilution ratio. 11. Operate the circulating pump. 12. Make sure there are no leaks and the solution is owing from the descaling reservoir through the heat exchanger and returning to the reservoir. 13. Run solution through the heat exchanger until the solution returning to the descaling reservoir comes out clear. (Changing to a fresh solution may be necessary during this process) 14. Disconnect all lines and drain all solution from heat exchanger. Properly discard of solution. 15. Position a container below the hot water outlet and connect cold water supply. Open cold water supply isolation valve and ush heat exchanger with clean water. 16. Shut cold water isolation valve and reconnect hot water supply to the water heater. 17. Reconnect electrical supply to unit, open water isolation valves, and return the unit to service.
6.1 Descaling procedure diagram
Circulating pump Flow direction

Filter Service valves

Drawing # MD1 CN revA 10/07
BBT North America Corporation Bosch Group Bosch Water Heating 50 Wentworth Ave Londonderry, NH 03053 Telephone (603) 882-1100 Fax (603) 584-1681 www.protankless.com techsupport@protankless.com