Warning – Technical Support at Bosch is an absolute nightmare!  Before you buy this product, do yourself a huge favor and call their customer support line to see how long it takes to get the help you need.  I averaged sixteen minutes to get to the first person and they are not a technician.  This becomes a very expensive water heater if the electrician charges eighty five dollars an hour and you do not have unlimited minutes.
You could place your phone number in the Q and have them call you back which I did.  In fact, I called back three times and put in all three of my contact numbers.  Today it took five hours for me to finally get a call back from technical support and they almost put me back in the Q.  However, the electrician had already left.
When you do call them, they are going to ask for your model number, which is typical, but then the questions get more complicated.  What is the wire size?  If you did not install this I am going to guess you do not have a clue what they are asking for.  How about your water pressure? Enough is not an acceptable answer.  What are the breaker sizes and are they single or double pole.  Okay, so if you are an electrician you might have two correct answers, however if you do not have the answers Customer Service will ask you to call back when you have them.  That would be to the number that was averaging sixteen minutes to get to the inquisition.
When your unit dies do yourself a huge favor and start with the trouble shooting section on-line.  Since I was clueless as to the gauge of wire coming from my panel to the heater, customer service graciously sent me a technical sheet via e-mail, so go online first, it will be the same sheet but with out an expensive phone bill.  If you need your installer to come out, print the technical support sheets for them, just in case.  We cheated and took the lap top to the garage.  Depending on what is wrong with your unit they are going to ask for a voltage test and an ohms test preferably by an electrician.  They will not help you trouble shoot if you have not had this done and the data is given to them. Beware, not all of the technical sheets are unit specific.  So a few of the diagrams are generic and can confuse installers because the diagram and the unit are different. 
The ohms test is what got my blood boiling hotter than a correctly installed Bosch.  I was reviewing the technical sheet and the top of my boilers when I asked customer service to clarify where I needed to place the probes.  They smarted off with “if you were an electrician, you would know”.  The next morning the electrician got on the phone and while reviewing the generic diagram made the mistake of asking the very same question.  Customer service asked what kind of electrician was he?  After, dishing out his companies information the electrician admitted that he was an electrician and did not specialized in just hot water heaters.  They hung up on us.  We called back and did the sixteen minute wait and managed to proceed with the ohms test.  The ohms test I am sure, is what tells them if the only two parts in the unit that have a ten year warranty, are bad.  Everything else in the unit has various warranty coverage depending on the installer.  Our unit had one year, because we installed it ourselves.
I would start with a visit to the parts list and jot down some of the prices for the replaceable parts.  There are not that many.  Notice, the mother board may not be listed.  Mine was $151.00. Calculate the cost of the electricians for at least two days (troubleshoot & replace).  The parts will need to be shipped to you, so add that in. Don’t choke when they give you the cost of overnight delivery and be mindful of day and time. Now how many days have you been with out hot water? If the board goes out, you might as well just buy a whole new unit. It will be faster and cheaper. Not to mention my electrician does not want to replace the board.  I am contemplating removing the unit from the wall and taking it to a computer geek.
When the water heater did work it was glorious!  Who ever invented it should be given sainthood.  Any one who claims the Bosch water heater does not get hot enough to turn you into a lobster did not have it installed correctly!  I do not take hot showers, I take steam showers and this will do it. There is a trick to getting lobster water, and I will bet my Bosch a lot of installers do not take the time to adjust flow to temperature.  This is critical!
What I have noticed is that there are installers that have not put a valve on the inflow or just importantly on the hot out flow.  We installed a Shark Bite Ball Valve on each.  This gives you the water shut off at the unit so you do not have to shut down the whole house to fix it.  We then used flexible steel braided hoses between the ball valve and the heater.  No soldering at all!  No worries about alignment of pipes to heater! EASY!
The valve on the out flow in conjunction with the temperature switch is necessary to create the lobster hot water.  The instructions on how to balance this are a tad difficult, only because it is difficult to relate to.  By closing off the water coming out of the unit you force the water to be in the boilers longer, by seconds.  The water has more contact with the hot elements and is now hotter.  You have to do it on the out flow so you can have the necessary pressure to keep the water going through the boilers.  I recommend having the wife at the shower end with a phone and installer controlling the valve and the temperature with the other phone.  When she says it is good mark the angle of the handle on the valve and the temperature knob.  In case for any reason some one messes with it you know where it ought to be. 
I have the Power Star AE115.  This is electric and designed basically for one appliance at a time.  I switched out all of my shower heads to low flow.  Remember, you have endless hot water.  You will save a fortune if your teenager is still taking one hour showers and you will still have hot water. 
If I replace the water heater every two and a half years, where is the savings? 
The last two locations that we have lived did not come up with a certified Bosch installer with in a hundred miles so I finally put in a zip code for a much bigger town.  My conversation was enlightening. If the new panel dies, I will not replace it with another Bosch.  It will be a different manufacturer.   Got to love those steel braided hoses. 

Recommended: Yes