Showing posts with label PCB Board. Show all posts
Showing posts with label PCB Board. Show all posts

Tuesday, March 21, 2017

Heat Sink Paste Application for Bosch Electric Tankless PCB Board Replacement

This will cover a little more in depth application of the heat sink paste that needs to be applied to the back of the triacs on the pcb board for the Bosch High KW electric tankless water heaters.  When you are replacing the PCB control board on a Bosch electric tankless water heater for the high KW units such as the AE-115/WH17 or the AE-125/WH27 you want to make sure to apply the heat sink paste that comes with the new PCB board.

The heat sink paste will come in a small syringe type applicator and a small amount will need to be applied to the back of each triac.  The triac's are the small black squares to the left of the PCB board labeled by the letter G in the picture below.  The Bosch AE-115/WH17 will have 4 small black triac's to the left of the PCB board and the AE-125/WH27 will have 6 small black triacs to the left of the PCB board.  There are service bulletins that show the PCB board replacement and heat sink application.  Bosch Service bulletin EP-22 will show the PCB board replacement for all the newer high KW units with polymer modules.    Bosch Service bulletin TWH-E2-22 will show the PCB board replacement for all the older high KW units with copper canisters.

For further questions or to purchase a new PCB control board visit this link:
or please call GlobalTowne at 888-726-9752 or visit our website.


Monday, December 2, 2013

PCB Boards for Powerstar AE-115 & AE-125 Electric Tankless


Bosch has made many upgrades and improvements to the Bosch Powerstar AE-115 and Powerstar AE-125 electric tankless water heaters.  One of the main improvements is in the Printed Circuit Board (PCB) that basically controls the heater.  Below is a list of the older and newer Powerstar AE115 & AE125 PCB board part numbers and the cutoff dates.

Older Powerstar AE-115 & AE-125 with Copper Canisters and serial number BEFORE #59:
AE-115 PCB Board - #93-793777
AE-125 PCB Board - #93-793778

Powerstar AE-115 & AE-125 with Polymer Modules and serial number 60 through 107:
AE-115 PCB Board - #93-793843
AE-125 PCB Board - #93-793844

New Powerstar AE-115 & AE-125 with Polymer Modules and serial number 108 and above:
AE-115 PCB Board - #8738701732 (87387017320)
AE-125 PCB Board - #8738701738 (87387017380)


New Bosch Powerstar AE-115 & AE-125 Electric Tankless

Bosch Powerstar AE-115 & AE-125 Electric Tankless Water Heaters

Ideal for replacing your electric storage tank water heater. The Bosch Powerstar AE-115AE-125 electric whole house tankless water heaters are compact and powerful and can be installed virtually anywhere inside the home. Advantages include endless hot water, reduced electricity costs and substantial space savings.

Designed to replace a 20 - 40 gallon electric tank. The Bosch Powerstar AE-115 & Bosch Powerstar AE-125 electric tankless water heaters are built to last. Each heater module is protected by an electro-mechanical thermal cut-out. If the temperature of any of the heater modules gets too high (over 195 degrees), then the cut-out will trip and cut the power to that heater module. If the cut-out trips, it must be reset while the circuit breakers are off. If you are not comfortable or qualified to perform this task, consult the original installer or a licensed electrician. This cut-out will only trip in exceptional circumstances. They have Plastic Polymer Modules and brass fittings. These small electric tankless water heaters can be installed virtually anywhere in the home and, of course, produce an endless supply of hot water.

There are many changes in the new Powerstar AE-115 and the AE-125 compared to the older models Powerstar AE-115 & AE-125.

The improvements for the New Bosch Powerstar AE-115 & AE-125 are:
  • The units overall height is shortened by 3 inches due to reconstruction and placement of the main PCB board in the bottom of the unit.  (AE115 PCB Board #8-738-701-732 (87387017320), AE125 PCB Board #8-738-701-738 (87387017380).  These PCB boards are required for all new Powerstar units with serial number beginning with 108 and higher.
  • The Heating element assembly modules inside the unit have been redesigned to change the flow of the water in the modules to a different angle so as to not allow the mineral deposits to build up on the elements.
  • There has been new single triac and dual triac PCB boards attached to the top of the heating modules as to give the heater more sensibility and maintain a more consistant heat.  (Single Triac PCB #8-738-701-733, Dual Triac PCB #8-738-701-723).
  • The Thermal Cutouts on the top of the heating modules have been redesigned to trip at a little lower temperature of 195 degrees F to keep the elements from being damaged and overheating and hurting the piping and modules.

The minimum activation rate required for the unit to activate. (Activation rates: AE-115 = 0.6 GPM, AE-125 = 0.8 GPM).

The AE115 & AE125 are designed for cold potable water only. These water heaters are not designed for preheated water or recirculation applications. Increase flow rate where ever possible if water is coming out too hot.

Verify incoming water supply is at least 30psi. For people on well systems, the recommended pressure range is 30-50psi.




Maximum flow rates for each unit are as follows. AE-115 = 2.3gpm, AE-125 = 3.5gpm.