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Bosch Pro Tankless Gas Water Heaters

Bosch Pro Tankless Water Heater Model 260 PN
This small gas tankless water heater is ideal for cottages, camps, and other specific applications where a small volume of hot water is desired. Its compact size means you save valuable floor space and is available in both natural gas (NG) and liquid propane (LP)
This Pro Tankless water heater features:
    Gas related specifications:
  • Maximum output: 58,400 Btu/hr
  • Power input: 30,735 - 74,900 Btu/hr
  • Thermal efficiency: 78%
  • Minimum output: 23,906 Btu/hr
  • Gas connection: 1/2" male NPT
  • Inlet gas pressure under maximum operation:
    • Propane gas: 10.5" - 14" water column
    • Natural gas: 5.7" - 14" water column


    Water related specifications:
    45°F rise at 2.6 gpm
    55°F rise at 2.1 gpm
    65°F rise at 1.7 gpm
    77°F rise at 1.5 gpm
    90°F rise at 1.3 gpm
  • Hot water connection: 1/2" male NPT
  • Cold water connection: 1/2" male NPT
  • Minimum water flow: 0.5 GPM
  • Water pressure: 30 - 150 psi
  • Connections at bottom of heater
  • Water resistant

  • Venting:
  • Vent diameter: 4"
  • Minimum height: 6' (with no elbows)
  • Vertical termination
  • Natural draft

  • Safety devices:
  • Flame failure device
  • Pressure relief valve
  • Over heat prevention

  • Standing pilot ignition
  • Weight: 26 pounds
  • Click here for dimensional drawing and clearance diagram
Image of Bosch GWH-260-PN tankless water heater
Model # Description Select Item(s)
GWH-260-PN-N Pro Tankless Water Heater - Natural Gas add to quote -->
GWH-260-PN-L Pro Tankless Water Heater - Propane add to quote -->
9620LA Accessory: Isolation Water Valves - Set of 2 add to quote -->

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items. (click here to find out why)
To request a price quote, simply select the items you are interested in by clicking the box in the "Select Item(s)" column next to the product.
Then click the button below to add the item/s to your quick quote request list.

- Or -Click here to view items that you would like to have quoted


Bosch Pro Tankless Water Heater Model 425 EF

Image of tankless water heater 425-EF

    Water related specifications:
    45°F rise at 4.6GPM
    55°F rise at 3.8GPM
    65°F rise at 3.3GPM
    77°F rise at 2.7GPM
    90°F rise at 2.3GPM
  • Water connection: 1/2" male NPT
  • Water pressure: 18psi-150psi
  • Minimum flow rate: .5GPM
This tankless water heater features:
  • The 425 EF has all the durability and performance of the 425 HN, with an added bonus - a built-in power vent. This makes the unit ideally suited for households requiring horizontal, through-the-wall venting only
  • On/off switch to activate system - makes the tankless water heater easy to use
  • Pressure relief valve included
  • Power venting with safety shutoff
  • Safety flame sensor at pilot burner
  • Automatic overheating protection shut-off sensor
  • Built-in corrosion resistant power vent
  • Adjustable water flow restrictor to ensure that water flow demand will not exceed the heating capacity of the heater
  • Electric ignition
  • 4" Vent
  • Weight: 44lbs.

  • Gas/power related specifications:
  • Gas connection: 1/2" male NPT
  • NG gas pressure: 7-14" WC
  • LG gas pressure: 11-14" WC
  • Electric supply: 120 Volts, 1.2 Amps (plug-in)
  • Click herefor dimensional drawing and minimum clearance diagram
Model # Description Power Input Energy Factor Thermal Efficiency Select Item(s)
GWH-425-EF-L Pro Tankless Water Heater - Propane 28,000-125,000Btu 81% 82% add to quote -->
GWH-425-EF-N Pro Tankless Water Heater - Natural Gas 28,000-130,000Btu 78% 80% add to quote -->
9620LA Accessory: Isolation Water Valves - Set of 2 - - - add to quote -->

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items. (click here to find out why)
To request a price quote, simply select the items you are interested in by clicking the box in the "Select Item(s)" column next to the product.
Then click the button below to add the item/s to your quick quote request list.

- Or -Click here to view items that you would like to have quoted


Pro Tankless Water Heater by Bosch Model 425 PN

Image of tankless water heater

    Water related specifications:
    45°F rise at 4.2GPM
    55°F rise at 3.4 GPM
    65°F rise at 2.9 GPM
    77°F rise at 2.4 GPM
    90°F rise at 2.1 GPM
  • Water connections: 1/2" male NPT
  • Minimum flow rate: 0.5 GPM
  • Minimum recommended water pressure: 30 psi
  • Connections at bottom of heater

This tankless water heater features:
  • Efficient modern day tankless water heater provides instant hot water and doesn't waste energy when you don't need hot water
  • Flame failure device
  • Pressure relief valve
  • Over heat prevention - to help make you water heater last
  • Water resistant - helps make water heater more durable
  • Weight: 35lbs

  • Gas/power related specifications:
  • Gas connection: 3/4" male NPT
  • Inlet gas pressure under maximum operation:
  • Propane: 10.5" - 14" water column
  • Natural gas: 5.7" - 14" water column
  • Maximum output: 91,525 Btu/hr
  • Maximum input: 117,000 Btu/hr
  • Thermal efficiency: 78%
  • Min. output: 23,906 Btu/hr

  • Venting:
  • Vent diameter: 5"
  • Minimum height 6' (with no elbows)
  • Vertical termination

  • Click here for dimensional drawing and minimum clearance diagram
Model # Description Select Item(s)
GWH-425-PN-L Pro Tankless Water Heater - Propane Gas add to quote -->
GWH-425-PN-N Pro Tankless Water Heater - Natural Gas add to quote -->
9620LA Accessory: Isolation Water Valves - Set of 2 add to quote -->

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items. (click here to find out why)
To request a price quote, simply select the items you are interested in by clicking the box in the "Select Item(s)" column next to the product.
Then click the button below to add the item/s to your quick quote request list.

- Or -Click here to view items that you would like to have quoted


Pro Tankless Water Heaters Models 345 ESR and 450 ESR
    Specifications for these water heaters:
    3.5 GPM at 45°F rise for model 345
    4.5 GPM at 45°F rise for model 450
  • Adjustable water temperature range: 115°F - 190 °F
  • Gas connection: 3/4" male NPT
  • NG gas pressure 5.5 - 8" WC
  • LP gas pressure 11-14" WC
  • Water connections: 3/4" male NPT
  • Vents vertically or horizontally with 3" stainless steel
  • Direct vent and sealed combustion
  • Maximum exhaust vent length: 39' (with one elbow)
  • Exhaust vent size: 3"
  • Intake vent size: 3"
  • Click here for water pressure vs GPM chart
    Features for these water heaters:
  • LCD screen displays temperatures, burner operation, and diagnostic codes
  • Separate temperature controls for domestic water heating and recirculation
  • Reset button
  • Flame failure device
  • Overheat prevention (temperature limiter)
  • Pressure switch (blocked vent protection)
  • Freeze prevention cycle - helps your hot water heater last longer
  • Pressure relief valve
  • Modulating gas valve
  • Noise is less than 50 db
  • Compact space saver: mounts on a wall with supplied bracket
  • Electric ignition
  • Electric supply 120 VAC - plugs in
  • Weight: 47lbs
  • Click here for dimensional drawing and installation clearance diagram
Image of tankless water heaters 345 and 450
Model # Max Flow Rate
with a 45°F Rise
Gas Type Rated
Efficiency
Gas Input
(BTU/Hr)
Max Output
(BTU/Hr)
Minimum Output
(BTU/Hr)
Select Item(s)
GWH-345-ESR-N 3.5 Natural Gas 82% 95,000 77,900 23,900 add to quote -->
GWH-345-ESR-L 3.5 Propane 82% 95,000 77,900 23,900 add to quote -->
GWH-450-ESR-N 4.5 Natural Gas 81% 120,000 98,400 35,500 add to quote -->
GWH-450-ESR-L 4.5 Propane 81% 120,000 98,400 35,500 add to quote -->
Model Description Select Item(s)
9620LA Isolation Valve Kit add to quote -->

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items. (click here to find out why)
To request a price quote, simply select the items you are interested in by clicking the box in the "Select Item(s)" column next to the product.
Then click the button below to add the item/s to your quick quote request list.

- Or -Click here to view items that you would like to have quoted


Bosch Pro Tankless Water Heater Model 715 ESR
Image of Pro Tankless water heater by Bosch model 715 ES This tankless water heater features:
  • 82% Thermal efficiency
  • Vents vertically or horizontally with 3" stainless steel
  • Can be used with multiple units for increased flow rates
  • High power pre-mix compact burner with low NOx emissions - good for the environment
  • Modulating water valve for improved temperature control
  • Compact space saver - mounts on a wall with a supplied bracket
  • Vent size: 3" or 4" stainless steel
  • Connections at bottom of water heater
  • Electronic ignition
  • Electrical supply: 120V (plug-in)
  • Amperage: 40mA (idle) - 2.5A (during operation)
  • Noise: 45 - 65 db
  • Weight: 67 lbs

  • Controls
  • Key pad interface control - for ease of use
  • LCD display with back light
  • On/off and temperature control switches with selection range: 100°F - 140°F
  • Default temperature 122°F
  • Reset button
  • Program button (allows you to set the temperature)
  • Real-time diagnostics for troubleshooting and informational purposes

  • Safety features:
  • Flame failure device
  • Pressure relief valve
  • Over heat prevention
  • Inlet temperature sensor
  • Outlet temperature sensor

  • Click here for dimensional drawing and minimum clearance diagram
Specifications for this tankless water heater:
    Water related specifications:
    45 °F rise at 7.2GPM
    55 °F rise at 5.9GPM
    65 °F rise at 5.0GPM
    77 °F rise at 4.2GPM
    90 °F rise at 3.6GPM
  • Minimum flow rate: .65 GPM (can be up to 1.6GPM depending on water temperature)
  • Max flow rate: 7.3GPM
  • Water pressure 30 psi - 150 psi
  • Water connections: 3/4" male NPT

  • Gas related specifications:
  • Maximum output: 160,500 Btu/h
  • Input: 19,900 Btu/h - 199,000 Btu/h
  • Inlet gas pressure under operation:
    • Propane: 9" - 14" water column
    • Natural Gas: 4" - 14" water column
  • Gas connection: 3/4" male NPT
  • NG gas pressure: 4"WC - 14"WC
  • LP gas pressure 9"WC - 14"WC
  • Modulating gas valve firing rate: 19,000BTU/hr - 199,00BTU/hr

Important Note: these water heaters are not designed for use above 4,500ft (above sea level) altitude, in mobile installations, or for space heating purposes. Outdoor installation requires an outdoor kit (PTOK). Also, if the inlet water temperature is higher than 140°F, then a 3-way valve or mixing valve must be installed.
Model # Energy Factor Description Select Item(s)
GWH-715-ESR-LP .82 Pro Tankless Water Heater - Propane add to quote -->
GWH-715-ESR-NG .81 Pro Tankless Water Heater - Natural Gas add to quote -->
PTOK - Outdoor Installation Kit add to quote -->
9620LA - Isolation Valve Kit add to quote -->

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items. (click here to find out why)
To request a price quote, simply select the items you are interested in by clicking the box in the "Select Item(s)" column next to the product.
Then click the button below to add the item/s to your quick quote request list.

- Or -Click here to view items that you would like to have quoted


Pro Tankless Water Heaters By Bosch Model C 800 ES

Image of C800ES tankless water heater

    Water related specifications:
    35°F rise at 10.1GPM
    45°F rise at 8.0GPM
    55°F rise at 6.4GPM
    65°F rise at 5.5GPM
    77°F rise at 4.6GPM
    90°F rise at 3.9GPM
  • Water connections: 3/4" male NPT
  • Minimum water flow: 0.65 GPM (can be up to 1.6GPM depending on water temperature)
  • Minimum water pressure: 30 psi

  • Gas/power related specifications:
  • Maximum output: 179,300 Btu/h
  • Input: 19,900 Btu/h - 199,000 Btu/h
  • Gas connection: 3/4" male NPT
  • Inlet gas pressure under operation (with a high hot water flow rate):
  • Propane: 9" - 14" water column
  • Natural Gas: 4" - 14" water column
  • Amperage: 40 mA (idle) - 65A (operation)

This tankless water heater features:
  • 92% Thermal efficiency
  • Vents vertically or horizontally with 3" PVC, CPVC, or ABS-DWV
  • Ability to cascade units for increased flow rates
  • High power pre-mix compact burner with low NOx emissions - good for the environment
  • Modulating water valve for improved temperature control
  • Noise: 45 - 65 db
  • Connections at bottom of heater
  • Weight: 74lbs

  • Controls
  • LCD display with back light
  • On/off and temperature control switches
  • Reset button
  • Program button - allows you to set the temperature between the range: 100°F - 140°F
  • Default temperature: 122°F
  • Real-time diagnostics for troubleshooting/informational purposes

  • Safety devices
  • Flame failure device
  • Pressure relief valve
  • Over heat prevention
  • Inlet temperature sensor
  • Outlet temperature sensor
  • Back flow temperature sensor
  • Exhaust gas temperature sensor
  • Click here for dimensions and minimum clearance diagram
Important Note: these water heaters are not designed for use above 4,500ft A.S.L. altitude, in mobile installations, or for space heating purposes. Outdoor installation requires an outdoor kit (PTOK). Also, if the inlet water temperature is higher than 140°F, then a 3-way valve or mixing valve must be installed.
Model # Description Select Item(s)
GWH-C-800-ES-LP Pro Tankless Water Heater - Propane add to quote -->
GWH-C-800-ES-NG Pro Tankless Water Heater - Natural Gas add to quote -->
PTOK Outdoor Installation Kit add to quote -->
9620LA Isolation Valve Kit add to quote -->

- Or -Click here to view items that you would like to have quoted


Comparison Chart
Model 260 PN 425 HN 425 EF 425 HNO 425 PN
Capacity 45°F rise at 2.6 gpm
55°F rise at 2.1 gpm
65°F rise at 1.7 gpm
77°F rise at 1.5 gpm
90°F rise at 1.3 gpm
45°F rise at 4.2GPM
55°F rise at 3.4GPM
65°F rise at 2.9GPM
77°F rise at 2.4GPM
90°F rise at 2.1GPM
45°F rise at 4.6GPM
55°F rise at 3.8GPM
65°F rise at 3.3GPM
77°F rise at 2.7GPM
90°F rise at 2.3GPM
45°F rise at 4.2 GPM
55°F rise at 3.4 GPM
65°F rise at 2.9 GPM
77°F rise at 2.4 GPM
90°F rise at 2.1 GPM
45°F rise at 4.2GPM
55°F rise at 3.4 GPM
65°F rise at 2.9 GPM
77°F rise at 2.4 GPM
90°F rise at 2.1 GPM
Power Input (Btu/hr) 30,735 - 74 900 28,000 - 117,000 LP: 28,000-125,000
NG: 28,000-130,000
28,000-117,000 31,000-117,000
Thermal Efficiency 78% 80% LP: 82%
NG: 80%
80% 78%
Energy Factor .64 .8 LP: 0.81
NG: 0.78
NG: 0.80
LG: .83
NG: 0.69
LG: 0.79
Dimensional Drawings Dimensions Dimensions Dimensions Dimensions Dimensions
Weight (lbs) 26 40 44 57 35

Model 345 ESR 450 ESR 635 ES 635 ESO 715 ES C 800 ES
Capacity 45°F rise at 3.5 GPM
(temperature is adjustable)
45°F rise at 4.5 GPM
(temperature is adjustable)
45°F rise at 6.4GPM
55°F rise at 5.2GPM
65°F rise at 4.5GPM
77°F rise at 3.7GPM
90°F rise at 3.2GPM
45°F rise at 6.4gpm
55°F rise at 5.2gpm
65°F rise at 4.5gpm
77°F rise at 3.7gpm
90°F rise at 3.2gpm
45°F rise at 7.2GPM
55°F rise at 5.9GPM
65°F rise at 5.0GPM
77°F rise at 4.2GPM
90°F rise at 3.6GPM
45°F rise at 8.0GPM
55°F rise at 6.4GPM
65°F rise at 5.5GPM
77°F rise at 4.6GPM
90°F rise at 3.9GPM
Power Input (Btu/hr) 95,000 (maximum) 120,000 (maximum) NG: 35,000-175,000
LP: 31,000-175,000
31,131 - 175,000 19,900 - 199,000 199,000 (maximum)
Thermal Efficiency 82% 81% NG: 87%
LP: 86%
NG: 87%
LP: 86%
82% 92%
Energy Factor 82% 81% NG: 0.85
LP: 0.86
NG: 0.85
LP: 0.86
LP: 0.82
NG: 0.81
LP: 0.90
NG: 0.89
Dimensional Drawings Dimensions Dimensions Dimensions Dimensions Dimensions Dimensions
Weight (lbs) 47 47 47 47 67 74


Please note: For potential safety reasons, we do not recommend using PVC to vent gas tankless water heaters.
For the best results, we recommend using Category 3 stainless steel gas vent pipe for all gas tankless water heaters.

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