Bosch Gas Tankless Water Heaters and Tank Loading Applications

Global Pro Tankless Supply is always trying to make it easier to figure out the right Bosch tankless water heater that is designed for the right application.  A tank load system, because of the added storage, can provide a high peak flow with fewer tankless units and lower installed cost. This will cover the basics for a tank loading application that will enable the user to have more domestic hot water and can also be set up for heating applications.  The Bosch gas tankless models such as the C1210ESC/C1210ES/C1050ES/C950ES/940ES and 830ES are all capable and designed to work with a tank loading applications.  Tank loading can be done using a standard tank heater as a storage tank or an indirect tank such as the Bosch SST Indirect Storage Tanks.

Many of the tank loading applications range from small singular tank loading to commercial tank loading such as for hotels and Inns.  Please see the diagram below for a basic design of a tank loading application.

For all the different tank loading applications please review the Bosch Applications Manual or call Global Pro Tankless Supply at 866-289-4652.

Replacement Heat Exchangers Now on Global Protankless Supply

Global Protankless Supply is now carrying the replacement heat exchangers for all the Bosch gas tankless water heaters.  The heat exchangers are made of high quality copper. Below is a list of all the heat exchangers and their current part numbers.  Older part numbers are also listed as part numbers have changed over the years.

Bosch Therm C1210ES / C1210ESC Heat Exchanger Part 8705406419 (87054064190 or 8-705-406-419-0).  This part is also the replacement Heat Exchanger for the older Bosch ProTankless 920ES and 920ESC condensing tankless water heaters.

Bosch Greentherm C1050ES-LP / C950ES-LP (Liquid Propane) Heat Exchanger Part 8738704026 (87387040260 or 8-738-704-026-0).

Bosch Greentherm C1050ES-NG / C950ES-NG (Natural Gas) Heat Exchanger Part 8738704117 (87387041170 or 8-738-704-117-0).

Bosch Therm C1050ES-LP / C950ES-LP (Liquid Propane) Heat Exchanger Part 8705406421 (87054064210 or 8-705-406-421-0).

Bosch Therm C1050ES-NG / C950ES-NG (Natural Gas) Heat Exchanger Part 8738721270 (87387212700 or 8-738-721-270-0).

Bosch Therm 940ES / 830ES Heat Exchanger Part 8738701985 (87387019850 or 8-738-701-985-0). This part is also the replacement Heat Exchanger for the Therm 940ESO, Bosch ProTankless 715ES, Bosch AquaStar 2700ES and 2400ES and the Bosch Evolution 500.  Older part numbers were 8705406422, 87054064220, 8-705-406-422-0, 8705406356, 87054063560, 8-705-406-356-0.

Bosch ProTankless 635ES / 635ESO Heat Exchanger Part 8705406285 (87054062850 or 8-705-406-285-0).  This part is also the replacement Heat Exchanger for the Bosch AquaStar 2400E, 2400EO, 250SX and 250SXO tankless water heaters.

Bosch Therm 520 Heat Exchanger Part 8705406386 (87054063860 or 8-705-406-386-0).  The Bosch Therm 520 Heat Exchanger Part 8705406386 is the replacement heat exchanger for all Bosch Therm 520PN and 520HN tankless water heaters and for all Bosch ProTankless 425PN and certain Bosch ProTankless 425HN (with serial numbers starting 686 and higher) tankless water heaters. It is also the replacement heat exchanger for all Bosch AquaStar 1600P and 1600H tankless water heaters. This heat exchanger replaces the obsolete 8705406275 (87054062750, 8-705-406-275-0) heat exchanger.

Bosch ProTankless 425 Heat Exchanger Part 8705406380 (87054063800 or 8-705-406-380-0).  The Bosch 425 Heat Exchanger is the replacement heat exchanger for the following Bosch ProTankless water heaters: 425EF, 425HN (with serial numbers starting 685 and lower) and 425HNO and the following Bosch AquaStar tankless water heaters: 125B, 125BO, 125BL, 125X, 125HX, 125FX.  This heat exchanger will also work with the following Bosch WR400 series tankless water heaters: WR400-1KV1P23S3100, W400KD5 P23S3100T2, WR400-3K V1B23S3100, WR400-7K V1G23S3195, WR430-3K VM1E23S3190 and WR430-3K VM1E23S3195.  Older part numbers were 8705406235, 87054062350, 8-705-406-235-0.

Bosch Tankless Water Heaters with New Built-In External Water Filters

Bosch Thermotechnology is always improving the gas-fired tankless water heaters and has recently improved all the sealed combustion tankless water heaters and have added a new hydraulic block on the bottom of all the units that incorporates a new built in external water filter.

The Bosch Greentherm C950ES and Bosch Greentherm C1050ES condensing heaters were designed with the new hydraulic block and external water filter built in.  The Bosch Therm C1210ES/ESC, Bosch 940ES and the Bosch 830ES have recently had the new hydraulic block and external water filter added.  After Serial number beginning with "301" will have the built in external water filter.

Built-in External Water Filter

All of the older Bosch "Therm" models before serial number 301 had the external water filter, part #8703035356 and was sold as an accessory.

Please contact Global Protankless Supply with any questions at 866-289-4652.

Using Bosch Tankless for Domestic Hot Water Recirculation

Bosch tankless water heaters can be used in recirculation applications and there are many different set ups for this such as direct recirculation and indirect recirculation.  Certain models of the Bosch tankless water heaters are approved for direct recirculation and are listed below.  Please be aware that the heat exchanger warranty of 15 years will be reduced to 3 years for direct recirculation.  This is stated in the warranty section of the installation manual.   All of the Bosch tankless water heaters can be set up for an indirect recirculation application in conjunction with a mini tank, recirculation pump and aquastat as described in the image below. The warranty for recirculation through an indirect mini-tank and not directly through the heater is 15 years.

Bosch tankless water heaters approved for direct recirculation:
Bosch Therm C1210ES
Bosch Therm C1210ESC (Commercial Unit)
Bosch Greentherm C1050
Bosch Greentherm C950
Bosch Therm 940ES
Bosch Therm 830ES

Diagram for Recirculation Application:
(This schematic is for illustration only and must not be used for actual installation without appropriate engineering and technical advise from a properly licensed professional in the locality where the installation is made).

Replacing an Aquastar 240FX with Bosch Therm 830ES

The Aquastar model 240FX was a unit that was distributed by Controlled Energy Corporation (CEC) many years ago.  The 240FX was manufactured by Takagi and was capable of 2 major applications at one time. The Aquastar 240FX was a 165K BTU unit, took 4" single wall sealed galvanized or 4" single wall stainless steel venting.  The 240FX took it's combustion air from the area where it was installed.  The 240FX could sit right on the ground as the water and gas connections came out the left side of the unit.  Wall mounting was also an option.  The 240FX was suppose to be vented out the sidewall of the home for a maximum of 15' using the FXHood as the termination.  The Aquastar 240FX has been obsolete for some time and now most of the parts are no longer made also.

The closest replacement for the Aquastar 240FX is now the Bosch Therm 830ES.  The Bosch 830ES is a 175K BTU unit and is good for 2 major applications at one time.  The 3/4" water and gas connection are on the bottom of the unit vs the left side of the Aquastar 240FX.  The venting on the 830ES must be either 3" or 4" stainless steel single wall venting (AL29-4C) venting up through the roof or out the sidewall.  There is a vertical vent kit, ES VVT vertical vent kit avalable and also a sidewall vent kit, AQ3ES sidewall vent kit for venting out the side of the home.  The intake air for the 830ES is taken from the outside also using 3" PVC and should be taken from the same wall or roof the exhaust is going out through.  Please refer to the link above for more information on the Bosch Therm 830ES or call us at 866-289-4652 with questions.

  BOSCH THERM 830ES

Bosch Therm Intelligent Cascading Kit

The Bosch Therm Intelligent Cascading Kit part number 7709003962 connects the Bosch Therm tankless water heaters together in an intelligent cascading setup.  Up to 24 Bosch Therm tankless water heaters can be connected together in intelligent cascading to deliver more GPM for each heater cascaded.

The Bosch Therm Intelligent Cascading Kit is designed to work with the following Bosch tankless water heaters:  C1210ESC, C1210ES, C1050ES, C950ES, 940ES, 940ESO, 830ES.

Please refer to the installation manual for proper installation of the Bosch Therm Intelligent Cascading Kit.

Installing the Bosch Therm High Temperature Kit #7736500074

The Bosch Therm High Temperature Kit (7736500074) allows the maximum temperature of the Bosch tankless water heater to be raised from its normal maximum of 140 degrees F up to 180 degrees F.

The Bosch Therm High Temperature Kit is designed to work with the following Bosch tankless water heaters:  Greentherm C1050ES, Therm C10505ES, Greentherm C950ES, Therm C950ES, C800ES, Integra 500, 940ES, 940ESO, Evolution 500 and 830ES.

The Bosch Therm High Temperature Kit is not designed to work with the Bosch Therm C1210ESC or the C1210ES.

The Bosch Therm High Temperature Kit is bascially some instructions and a couple Jumpers.  The installation of the kit is very easy.  There are 2 small jumpers that will be inserted on the control board in the Bosch tankless water heater.

Installing the Bosch Therm High Temperature Kit:
*Make sure power to the unit is TURNED OFF!
1.  First remove the front cover of the heater.
2.  Then remove the screws holding the control unit on the bottom of the heater.
3.  Once the control unit is detached then you can access the back of the control unit and you will see a square cutout on the back and some pins where the jumpers will be inserted.  The pins are labeled JP5, JP6, JP7, JP8 and JP2 on the bottom.  Insert the 2 small jumpers from the high temp kit into pins JP7 & JP8.
4.  Double check connections and then screw the control unit back into place and put the front cover on.
5.  Turn the power back on and the heater should default to 120 degrees F.  You will now be able to raise and lower the temperature on the unit from 100 - 184 degrees F.  Please take into consideration that when the heater is set at say, 180 degrees that the unit will only be able to flow about 1.5 - 3 GPM depending on the heater you have.  The higher the temperature the lower flow you will get.

Replacement Heat Exchanger #87054064220 for Bosch Protankless 715ES

The replacement heat exchanger for the Bosch Protankless 715ES has a new part number of 87054064220. This part number has changed from the original part number of 8705406356.  The heat exchanger part number 87054064220 is also the replacement for Bosch Therm 830ES, 940ES, 940ESO and the Bosch Evolution 500.

This replacement heat exchanger is also good for the retail heaters Bosch 2400ES/2700ES.

Replacing Older Bosch Tankless with The Bosch Therm 830ES

The Bosch Therm 830ES Non-Condensing tankless water heater is a top performance, gas tankless water heater from Bosch. This 199,000 BTU heater is designed for residential applications and can deliver hot water up to 140 degrees F with a 8.3 GPM flow rate at a 35 degree rise.  Not approved for space heating applications.

This Energy Star approved tankless water heater can produce enough hot water for 2 major applications in most homes.

The Bosch Therm 830ES heater features an electronic ignition system and can vent through either 3 inch or 4 inch diameter stainless steel vent pipe either through the side wall or up through the roof. A stainless steel concentric side-wall venting option (ESHCK-Full-Kit) is also available.

The Bosch 830ES heater comes with built-in Freeze Protection but it does not come with the 3/4" PRV and the External Water Filter.  The freeze prevention kit is designed to provide protection for the water heater down to approximately 5°F for short term conditions only. It will not protect the appliance in areas where the temperature is routinely expected to be below freezing.  The freeze prevention kit will not protect plumbing outside the appliance from freezing.

The Bosch Therm 830ES is a wholesale model heater and sold to licensed plumbers and contractors. The new Bosch Therm 830ES is a close replacement for older models such as the Bosch 250SX/250SXO,  635ES/635ESO and the 2400E.  Please be aware the 830ES is 7" taller, 2.375" wider and 2.75" deeper than the previous models. The Bosch 830ES is a direct replacement for the Bosch 2400ES.  For outdoor installations the Bosch 830ES would require the BTOK Outdoor Kit.

The Bosch Therm 830ES comes with a limited 15 year warranty on the heat exchanger and 5 years on all other parts.  Service and labor costs are not covered.

Replacement Heat Exchanger for Bosch 830ES/940ES/940ESO and Evolution 500

The Bosch 940ES, 940ESO, 830ES and the Bosch Evolution 500 Heat Exchanger Part 8705406422 is the replacement heat exchanger for all Bosch Therm 940ES, 940ESO, 830ES and the Bosch Evolution 500 tankless water heaters.

This part is also the replacement Heat Exchanger for the Bosch Aquastar 2400ES and 2700ES tankless water heaters.

Bosch Wireless Remote Control TSTAT2

The Bosch Wireless Remote Control TSTAT2 for the Bosch Therm and Protankless models 635ES / 635ESO / 715ES / C800ES / C920ES / C920ESC / C830ES / C940ES / C940ESO / C950ES /    C1050ES / C 1210ES / C 1210ESC / Integra 500 / Evolution 500 allows you to program your Bosch tankless gas water heater to a comfortable and safe temperature from around your home from a distance of up to 98 ft.

The TSTAT2 remote is particularly useful if you own a jacuzzi or hot tub that requires a hotter water temperature than you normally desire for regular shower use.

Please note that the electrical control board of the older Bosch 635ES / 635ESO heaters must be removed and opened in order to install the wireless receiver circuit board to enable the use of the TSTAT2 Wireless Remote Control.

The Newer Bosch models, 715ES / C800ES / C920ES / C920ESC / C830ES / C940ES / C940ESO / C950ES / C1050ES / C 1210ES / C 1210ESC / Integra 500 / Evolution 500 tankless water heaters have been redesigned to make the installation of the wireless receiver circuit board much easier. The circuit board is basically a plug and play unit.

The TSTAT2 controls the temperature of your water heater and does not have a reset button.   If the heater has an error then a code will be on the display of the heater and the user has to go to the heater to reset it from there and should document the error and then see if it returns after resetting.

The TSTAT2 Wireless Remote Control for Bosch 635ES / 635ESO / 715ES / C800ES / C920ES / C920ESC / C830ES / C940ES / C940ESO / C950ES / C1050ES / C 1210ES / C 1210ESC / Integra 500 / Evolution 500 features the following:

• LCD displays temperature, error codes and functions
• Temperature measured in °C or °F
• Low battery level indicator
• 98 feet user range
• Alkaline AA LR6 2x1.5V battery power 915 MHz
• Security lock function
• IP X6 Protection
• Priority function - temperature cannot be modified by other user interface when water is running

Don't forget to periodically change the two AA batteries in your Bosch wireless TSTAT2 thermostat as they will certainly corrode over time. The batteries in TSTAT2 thermostats that are kept in bathrooms will corrode faster than in other less humid environments, such as kitchens. Your batteries should be checked yearly for any signs of corrosion and replaced every five years in any case.

New Bosch Tankless Universal Control Board

Bosch has released a new Universal Control Board (part number 87072073680) for their "World Two" tankless water heaters.

The board comes with three jumpers and instructions as to where to place those jumpers to make the board model-specific.

One jumper specifies if the heater is a 175,000 BTU or a 199,000 BTU appliance, another jumper specifies the gas type - NG or LP, and another jumper specifies if the heater has a surface-mounted outlet temperature sensor or is using a newer immersed sensor that is included on some recent production heaters.

Additionally, the world two universal control board is able to automatically determine if it is being used on a condensing or non-condensing tankless water heater.

This universal control board can be used on the following Bosch tankless water heaters for both natural gas and propane:

• C1050ES, C950ES, 940ES, 940ESO, 830ES
• C800ES, 715ES
• Integra 500, Evolution 500
• AquaStar 2700ES, AquaStar 2400ES

Call us at 866.289.4652 for more details or to place your order.