There are 2 types of people. Those that would rather know, and those that would rather hope. I was in the latter group like a saint for a long time. I hoped my Bosch tankless GWH-635-esn tankless would deliver me from evil and provide the delightful clean wholesome experience i was sold on. For 8 years i did what i could, including but not limited to, increase the gas pipe size, decrease the gas pipe run, shorten the exhaust duct, preheat the tap water coming in, spend months talking to tech support. My customer number is 42628. Why would i remember that number? Well after a while i decided to write it down so i could get to the head of the que. Then i used the hell out of it. Bosch tech support is busy. 8 years, i treaded up and down the floors from the master bedroom to the basement. Up and down, up and down. Reset, reset, power down, power up, cross the cold wet fingers for good luck in hopes that i wouldn't have to towel off and try it again in the morning, even tho i really needed to shower. The navy shower does work tho. Just a dash of water, suds off, rinse. Explain the whole thing about shrinkage again, and get under the covers quick to stop the shivering. Yes my fellow conscientious people, that was my Bosch experience. But then one day i decided, like a boat owner who'd grown disinterested in the sea, to abandoned ship and let it go. That being the idea of a tankless water heater. Then i went on craigslist.com under appliances, and found a portal to normalcy. It's been 3 weeks! I haven't had a single problem. I turn on the shower, it gets hot, and voila, i take a shower. It's amazing what a difference there is with a Rennai on my wall where the Bosch used to be. It really is.