20 Most Recent Bosch PowerStar AE115 Tankless Water Heater... - Page 2 Questions & Answers


Here are some possibilities and checks.
  1. The high temperature thermal cut-out has tripped. This would general shut off the Neon Light as well as the elements. However, even though your light is on check anyways.
  2. The flow switch not activating, Shut off the power to unit. Open the unit and observe if the flow switch activates when the water is turned on. If not then you have a faulty flow switch.
  3. Water flow to high. Turn the hot water tap on at the sink, adjust the outlet service valve until the water comes out of the tap at the required temperature, increase flow for cooler, decrease for hotter.
  4. The power selector screw not turned all the way to high. Check and turn all the way to high
  5. Element not working. Turn of the electricity to unit and test the resistance of the element. Here are the proper resistance for the element (240 volts, 40amps has a resistance of 2x12ohms) if no resistance than one or both elements need replacement.
I hope this gives you some more areas to check. Thanks for using FIXYA, Good Luck to you and have a great weekend. Jeff

Bosch PowerStar... | Answered on Nov 18, 2012


You've done the required first-step troubleshooting and maintenance.
If thermal cutout keeps tripping, and unit is actually reaching 185, then something is wrong with wiring, temperature sensor, gas valve, or PC board. Or combination of factors.
Call service technician, and open following link for some Bosch tankless resources including Bosch contact information:
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

Bosch PowerStar... | Answered on Nov 25, 2011


There is a pressure cut-out in those heaters. It detects that there is no flow when the pressure builds up in the system so that it only works on hot water demand. Is this perhaps not your problem, that the pressure switch is set too high or your water pressure itself is too high and not dropping enough to close the heater element switch when water is drawn off?

Bosch PowerStar... | Answered on Jul 30, 2011


I don't have specific suggestion for tankless tripping breaker or if that is a circuit breaker problem or a tankless problem.

1) Move wires to another same-size breaker and see if problem persists.

2) Compare amp draw on tankless label with wire size and breaker size amp rating.
For example 30 amp breaker using 10ga wire is rated for 80% of listed amps or 24 amps.

3) If you are drawing full 30 amps, then 30 amp breaker is getting hot. Breaker trips with heat. Older breakers can trip more easily.
http://waterheatertimer.org/How-to-replace-circuit-breaker.html

4) Before calling service technician, open following link for Bosch troubleshooting steps.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

5) Be sure to read manual for yearly maintenance requirements.

6) Add a tempering tank for incoming cold water problem.
http://waterheatertimer.org/Tempering-tank.html

7) All gas tankless brands can be repaired by homeowner for $330.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Bosch PowerStar... | Answered on Apr 25, 2011


The crackling noises is just from air in the water and should be of no concern. If you are having a problem of heating up the water with the unit it is most likely do to water moving too fast through the lines. Ideally, there should be a shutoff valve installed on both sides of your heater (makes for easy removal if it needs to be serviced). But if you turn off the valve about 1/4 to 1/2 way on the one on the "in" side of the heater (where the cold water enters) then you will slow down the water going through the heater and this will give the water a better chance to heat up. This should alleviate the heating problems you are having. If you do have a shutoff valve on the cold (in) side of the heater, shut it off about 1/4 to 1/2 way and then go to your shower and turn the hot on all the way (no cold). Wait for the water to warm and test the water by hand to see if it is the temp you want. If it is still not warm enough, turn the hot on the shower DOWN just a little. This will actually make the water hotter. I know this doesnt seem right but it will. On the other hand, if the water coming out with the hot water fully turned on is too hot, then just turn on a little cold water at a time until the water is the temp you want. Remember, always give the water plenty of time to get from the heater to the shower before you decideof its the right temp. Ideally, you should be able to turn the hot water on all the way and get the hot temp that you want and if you want to cool it down, just turn the cold on just a little bit until it is where you want. I'm fairly sure the problems you are having are due to the water going too fast through the unit and once you adjust that and understand better how these tankless heaters work, you wont have any more trouble. They are difficult to get used to after using conventional water heaters and the manufacturers arent very good about giving you these hints so they will work properly. You will need a professional to uninstall and hopefully this will work and you want have to. But if you do, it requires shutting off the water to the unit. Shutting off the pwer to the unit. Unattaching the water lines to the unit and then unattaching the electric lines from the junction box or wherever they are attached. The heater then can be removed from the wall by unscrewing the screws from the hangers which hold it to the wall.

Bosch PowerStar... | Answered on Mar 27, 2011


Bosch parts are sold at Houseneeds:
Each part comes with service bulletin and disclaimer advising you to have trained service technician install part to save money.
http://www.houseneeds.com/shop/heatingproducts/waterheating/parts/bosch2400espartsbuy.asp

Open following link for Bosch tankless troubleshooting resources, including Bosch contact information, typical manuals, error codes, tech support, parts, fuel-saver calculator, service bulletins, water heater forum, fixya links, disclaimers, and links for finding service technician.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

Add a comment for more free help.
Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

Bosch PowerStar... | Answered on Mar 24, 2011


You posted under Bosch electric tankless.
I don't know specifically how to fix your tankless from information given.
Tankless problems can be simple or complex, and include internal and external factors best gauged by experienced service technician who is there and can put hands on the appliance.
You can also glean information from the service technician how to best maintain your tankless unit, since they require yearly maintenance, such as de-liming.

Open following link for Bosch tankless troubleshooting resources, including Bosch contact information, typical manuals, error codes, tech support, parts, fuel-saver calculator, service bulletins, water heater forum, fixya links, disclaimers, and links for finding service technician.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

Add a comment for more free help.
Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

Bosch PowerStar... | Answered on Mar 24, 2011


This model is known to have problems with its Thermal Cutout this regulates the maximum water temp and can cause the unit to overheat when it does not shut off the heat source. In some residences low water flow and or a obstruction (common if you have well water) in the filtration and water treatment system can cause the same problem. Basically the unit can have overheating problems and the heat exchange coils are be prone the effects of hard water (if that applies to your water supply) and can lead to future service of descaling the units coil/coils (can be expensive). Buying any used unit with many mechanical parts and other components always have the potential to have problems new so i would not recommend a used unit of this type.

Also, This unit is limited due to the fact that the unit require­­­ incoming water to be cold and you cant use any sources of pre heated water (many people are starting to utilize alternative energies such as solar water heaters, wood boilers, and other relatively free or low cost). For example, using recovered heat from a boiler or indirect hot water tank or other to reduce the energy (cost) by raising the systems initial water temperature.

Are you heating a concrete floor with radiant heating? if so it would be far more cost effective to use either a loop off your existing system (a new zone) or you could add a oil fired or LP (gas) fired water heater and utilize the efficiency of a separate system and the fact that a hot water heater stores and super insulates the water it heats.



if you have any questions please feel free to let me know

Bosch PowerStar... | Answered on Feb 06, 2011


Reset the control unit per the manual.

Bosch PowerStar... | Answered on Sep 26, 2010


Call BOSCH 800-798-8161 tech support. If it is not too old even out of warranty they will help diagnose. You can get parts for free in warranty and buy parts at www.houseneeds.com out of warranty. If it gets hot fast and then stops, one of the "Thermal cutout switches" is cutting out. The water flow it probably blocked. (Just a guess) On many models they have a "Screen" and or a "Gromet" that you can clean out. If your water is really hard the whole unit may be clogged. I believe the "SAFE" thing to do is replace it but again I say CALL BOSCH TECH SUPPORT. I have also heard of people "Cleaning the whole units with vinigar, like cleaning a coffee maker. TURN OFF POWER! TURN OFF H20! REMOVE UNIT, then clean.

Bosch PowerStar... | Answered on Aug 22, 2010


Bosch will give free tech support to figure out your problem. 800-798-8161. Check your paperwork if it is still in warranty they will send free replacement parts. If out of warranty go to www.houseneeds.com for replacement parts. Check the "Flow switch" a long two tubes with two little micro switches and a little round hat or sombrerro that MOVES when the H20 is turned on. IF YOU HAVE ONE OF THESE, it should turn on one or two micro switches. If you have this part it should be described in your "Owners manual". If you no longer have the owners manual you can get one free at www.bosch.com It will give you trouble shooting guide and or you can call them even out of warranty then purchase replacement parts.

Bosch PowerStar... | Answered on Aug 22, 2010

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