I installed one of these in December of 2010. FYI,I am the owner and installer and not a plumber. I had no problems with the installation. There was an initial startup problem due to a stuck diaphragm, but the Bosch tech support was able to talk me through this and since then the unit has, by and large, performed well enough except for one thing. The unit is located some distance from the primary user. It serves the clothes washer, dishwasher, and the kitchen sink primarily. It can take up to 30 seconds to tell if you have hot water depending on where you set the water flow. Unfortunately, it doesn't always light. To get it to light, you have then cycle the water on and off until it does and eventually it seems to light. I've talked to Bosch about it and until something fails, there is not much they can tell me. This situation has been very frustrating, esp. for my wife, because you never know when it has lit, or even if it will. So, I rigged up circuit which uses a phototransistor to generate signal which then will turn light up an LED located at the kitchen sink. The PT uses the green indicator light on the control box to know when to turn on. Now we know right away if it's lit or not and cycling the water on and off to get it going is not such a big deal... wife happy. However, one should not have to do this and having unreliable hot water is totally unacceptable. I'm hoping to hear from other owners as to what they may done if they have this problem and decide if I should return the unit while it is still under warranty. If anyone should want to know how to set the indicator circuit, I'll be glad to supply you with details. It is very inexpensive.