Thursday, May 14, 2015

PCB Control Boards for Powerstream Pro & Bosch Tronic 5000 Electric Tankless


The PCB control board (Printed Circuit Board) is a thermostatically controlled circuit board that allows the whole house electric tankless water heater, models WH17, WH27 & WH36, to be manually controlled by a temperature dial that would range in temperature from 86-131 degrees. The PCB in conjunction with a flow transducer enables the PCB to turn on additional elements in the heater as necessary depending on the amount of gallons per minute (gpm) flowing through the heater.

The PCB would recognize many factors in the function of the heater to maintain a steady temperature and all of this is determined on where the temperature knob is set to, the gpm flowing through the heater, and the temperature of the incoming ground water.

To obtain the maximum heating potential of the Bosch Tronic 5000 electric tankless water heater it must be wired correctly and have the full required voltage to the unit. The Bosch Tronic 5000 WH17 would require 2 independent double pole 40 amp breakers wired with 8 gauge wire and could draw a maximum of 80 amps at full flow through the heater. The WH17 would require the home to be supplied with a minimum of a 150 amp service. The Bosch Tronic 5000 WH27 would require 3 independent double pole 40 amp breakers wired with 8 gauge wire and could draw a maximum of 120 amps at full flow through the heater. The WH27 would require the home to be supplied with a minimum of a 200 amp service.  The Bosch Tronic 5000 WH36 would require 3 independent double pole 60 amp breakers wired with 6 gauge wire and could draw a maximum of 180 amps at full flow through the heater. The WH36 would require the home to be supplied with a minimum of a 300 amp service.

The maximum inlet water temperature allowed into the electric tankless is 86 degrees Fahrenheit.

The Bosch Tronic 5000 WH17, WH27 & WH36 have had many upgrades and engineering improvements over the years. In January 2007 the WH17(RP17PT) & WH27(RP27PT) went from having copper canisters that contain the heating elements to an upgraded Polymer module. The PCB control board was also upgraded to maintain a more steady temperature that works with the heating elements in the polymer modules.

Below are the designated PCB control board part numbers for the units before and after 2007.

Before 2007 with serial #60A 00000 or lower:
Powerstream Pro RP17PT PCB with copper can units, part #93-793777
Powerstream Pro RP27PT PCB with copper can units, part #93-793778

After 2007 with serial number between #60A 80000 - 107:
Powerstream Pro RP17PT PCB with polymer units, part #93-793843
Powerstream Pro RP27PT PCB with polymer units, part #93-793844

Newest Bosch Tronic 5000 units with serial number after 108:
Bosch Tronic 5000 WH17 PCB with polymer units, part #8738701732
Bosch Tronic 5000 WH27 PCB with polymer units, part #8738701738
Bosch Tronic 5000 WH36 PCB with polymer units, part #8738701744


Friday, April 3, 2015

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.

Thursday, March 26, 2015

Backdraft Reducer #9301BFP for Bosch Tankless Water Heaters


The Heat Fab backdraft reducer (9301BFP) is the preferred option for limiting backdraft for the Bosch Condensing tankless water heaters (see fig. 22).

Note: The following solution is available only for 3" diameter venting.

In cold climates, components of a tankless water heater can freeze and burst from negative draft. A leading cause of negative draft is combustion appliances in the building not being supplied with sufficient combustion air. A wood stove or furnace can pull its combustion air from the water heater‘s vent pipe, allowing the cold incoming air to freeze the cold water in the heat exchanger. The best prevention for this risk is two pipe venting which draws the appliance combustion air from outside creating a positive pressure inside the unit.

For this solution to be effective, the internal flapper must be 100% closed when the water heater is not running. Refer to Figures 24 and 25 for preferred installation positions in the vent system.

Installation considerations:
• Install damper per the supplied manufacturer‘s instructions.
• The damper is only to be used in the exhaust vent piping.
• Ensure directional arrow on damper label faces in the same direction as exhaust flow.
• If installed horizontally, the axis must be horizontal or slightly pitched up towards termination to ensure damper closes 100% when heater is not running.
• To allow accessibility, damper must not be installed in an enclosed section of vent pipe.
• Do not install damper in unconditioned spaces (e.g. attics) Condensation can build up while the heater is running which can later freeze and potentially block the flapper.

The Bosch C1210ES/ESC, C1050ES & C950ES are all approved to use the Backdraft Reducer. 


Thursday, March 19, 2015

Phasing out of Bosch Therm 940ESO Outdoor Unit

Bosch is phasing out the Therm 940ESO model tankless water heater in Natural Gas, Part Number 7738000001 and Liquid Propane, Part Number 7738000002.

Bosch will continue to still make the Bosch Therm 940ES NG & LP tankless water heaters. The Bosch Therm Outdoor Kit (BTOK) will be sold as an accessory for outdoor installations.

The Phase out of the Bosch Therm 940ESO outdoor unit will be immediate. Please see the list below for model numbers, color changes by manufacturing date and BTOK model numbers.

Bosch Therm 940ES NG - #7703311076
Bosch Therm 940ES LP - #7703411073
(Gray Models, FD prior to FD420 - White Models, on or after FD420)

BTOK Outdoor Kit - Gray #7709003913
BTOK Outdoor Kit - White #7736502448

Please call Global Protankless Supply at 866-289-4652 for further questions or ordering.

Friday, March 13, 2015

Bosch Greenstar Intelligent Cascade Module (ICM) #7719003528


Bosch is always working on new ways to improve their products and has recently came out with an Intelligent Cascading Module (ICM) part #7719003528 for the Bosch Greenstar gas-fired wall-hung boilers.  The ICM modules are designed to control cascade systems.  A cascade system is a heating system where several smaller boilers are connected in parallel to achieve higher output.  The Bosch ICM modules are only suitable for controlling Bosch Greenstar boilers with BUS-enabled Heatronic 3 systems.
One Bosch ICM module can control up to 4 Greenstar boilers.  By conecting up to 4 ICM modules, up to 16 boilers can be linked to form a single cascade.  Depending on the heating system controls used, a cascade system with up to 4 or up to 16 boilers can be created.  The maximum number of boilers that can be connected and the number of ICM modules required for the different systems are shown in the table below.



Tuesday, January 20, 2015

Bosch Tankless Water Heaters and Pressure Regulating Valves

  1. Pressure Regulating Valve is a valve that automatically cuts off the flow of a liquid or gas at a certain pressure. Regulators are used to allow high-pressure fluid supply lines or tanks to be reduced to safe and/or usable pressures for various applications.

  2. Bosch tankless water heaters work on water pressure and flow.  Some people experience fluctuating temperatures sometimes if they are on a well system as the well pump has a high and low setting for when the pump comes on and off.  Most common well pumps are set to like 30 - 55 psi of pressure.  So when you are using the hot water and if the pump kicks on during this time you could see a change in flow and pressure which will change the flow and water temperature out of the Bosch tankless water heater.  
  3. A Pressure Regulating Valve installed on the cold water line before the Bosch tankless water heater can be set at the low PSI such as 30 psi and then will always maintain that 30 psi consistently whether the pump kicks on or not.
  4. There are all sorts of different pressure regulating and pressure reducing valves on the market.  

Friday, December 19, 2014

Wattages and Ohms Law for Electric Tankless Water Heaters


Electric Heaters and heating elements become hot due to a voltage being pushed through a wire.  The resistance in the wire measured in Ohms creates the heat.  The more resistance the hotter the wire gets. The more voltage pushed through the wire, the hotter the wire gets. Simply the smaller the wire (or the longer the wire run) the more resistance it gives to the voltage passing through.

So as voltage increases the wattage will increase four-fold.  As the voltage decreases the wattage will decrease by a factor of 4 as well.  The below table shows the percentage of drop or gain with different applied voltages to a heating element.


Rated at 277 volts the expected wattage % is
277 applied 100% (rated Wattage)
240 applied  75%
230 applied  69%
208 applied  56%
120 applied  19%


Rated at 240 volts the expected wattage % is
277 applied 133%
240 applied 100% (rated wattage)
230 applied  92%
208 applied  75%
120 applied  25%  (1/4 wattage)


Rated at 120 volts the expected wattage % is
240 Applied  400%  (4 times wattage - Dangerous) 
208 Applied  300%  (3 times wattage - Dangerous)
120 Applied  100%  (rated Wattage)
110 Applied   84%


This is all based on Ohm's Law.

Simple Ohms Law equations are:

Amps = WATTS / VOLTS
Watts = VOLTS x AMPS
Volts =  AMPS x OHMS
Ohms = VOLTS / AMPS


A Conductor Wire's resistance is constant based on wire size and length.

A heater's watt rating is based on the wire used in the heating element and the voltage applied.

To get a 9.5 kilowatt rated heater run at 240 volts; a wire with a resistance of 6.6 Ohms is used. (If there are two elements in the heater, then each is rated at 4.75 kw and the resistance of the wire would be 12.12.)