Bosch Appliances GWH 260 PN/HN2 Sizing tankless water heaters, Definitions, Rule of thumb sizing

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Applications manual

 

 

2.1 Sizing tankless water heaters

Definitions

Major applications (2 GPM or more): Washing machine, bath tub, shower nozzle

Minor applications(1.5 GPM or less): Low flow 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 conjunc- tion with the charts on the next page.

Sizing by Chart

Measure the flow rates at each fixture that will be used simultane- ously and add them together. If only one application will be used at a time measure each fixture and use the maximum flow rate observed.

Rule of Thumb Sizing

Model Number

Number of Major

Number of Minor

 

Applications

Applications

 

 

 

GWH 715 ES

2

0

 

 

 

GWH C 800 ES

2

1

 

 

 

GWH 425 HN/PN/EF

1

1

 

 

 

GWH 425 HN/PN/EF

0

2

 

 

 

GWH 260 PN

1

0

 

 

 

RP17PT

1

0

 

 

 

RP27PT

1

1

 

 

 

Using a known volume container, record several fill times. Per- form the calculation below to determine the flow rate (a one gallon fill time of 30 seconds is 2.0 gallons per minute (GPM):

Flow rate (GPM) =

Volume (gallons)

x 60

sec

Fill time (sec)

min

 

 

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 flow rate of 2.0 GPM at a 65˚F 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.

Application manual 11.2007

Bosch Water Heating

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Contents Applications manual Table of Contents Introduction Sizing by Chart Sizing tankless water heatersDefinitions Rule of thumb sizingGas Appliance Sizing Chart Features GWH 715 ES Installation SpecificationsApplications manual GWH 715 ES Installation Clearances Installation guidelinesGWH C 800 ES Installation Clearances GWH C 800 ES Installation SpecificationsGWH C 800 ES Technical Specifications GWH C 800 ES Outdoor Installation for GWH 715 ESDescription Min Distances GWH 450 ESR Installation Clearances GWH 345 ESR Installation SpecificationsGWH 345 ESR Technical Specifications GWH 450 ESR Installation Specifications GWH 450 ESR Technical SpecificationsGWH 425 EF Installation Clearances GWH 425 EF Installation SpecificationsGWH 425 EF Technical Specifications GWH 425 HN Installation Specifications GWH 425 HN Installation ClearancesGWH 425 HN Technical Specifications Establish a one-foot rise before any elbowsGWH 425 PN Installation Clearances GWH 425 PN Installation SpecificationsGWH 425 PN Technical Specifications GWH 260 PN Installation Specifications GWH 260 PN Installation ClearancesGWH 260 PN Technical Specifications Technical Specifications Maximum flow rate at given temperature riseElectrical requirements Powerstream Pro RP1P, RP2P, RP3P, RP7P, RP9P,RP12PT Ariston Pro GL2.5Ti, GL4Ti, GL8Ti Potable water Point-of-use applicationsIntroduction Temperature and pressure Service valveRelief valve SinkService valve Sink Flow direction Temperature and pressure relief valve Sink Service valves Low flow Flow direction ShowerService Sink valves Powerstream Pro RP17PT or RP27PTPowerstream Pro whole house applications Standard tub fixtureHotCold Symbols Bosch ProTankless gas water heaterHot Cold Parallel unit applications Pressure relief valves Bosch GWH 715 ES Bosch GWH C 800 ESCascading unit applications GWH 715 ES and GWH C 800 ES cascadingPressure Cold water Feed DHW Single unit tank loading application plumbing diagramBosch GWH 345 ESR Bosch GWH 450 ESR Single Unit Tank Loading Electrical Diagram ESR control BoardRadiant space heating and DHW plumbing diagram Cold waterFeed External storage tankRadiant Space Heating and DHW Electrical Diagram Radiant space heating and DHW electrical diagramFan Coil Cold water Fan coil space heating and DHW plumbing diagramBosch GWH 345 ESR, Bosch GWH 450 ESR Fan Coil Space Heating and DHW Electrical Diagram Fan Coil space heating and DHW electrical diagramDrawing # BB OL RevA 10/07 Baseboard Space Heating and DHW Electrical Diagram Drawing # Bbaol RevA 10/07 Pkps Insulate piping Cold water feed Terminal box Baseboard Radiant Panel Back Flow preventerDrawing # EID Bbol CN revA 10/07 Descaling procedure Circulating pump Flow direction Filter Service valves Applications manual Applications manual Applications manual Applications manual BBT North America Corporation