Call me crazy, but I installed this in a 4000 square ft home with 4 bathrooms. It is just 3 of us though. So I think I can answer some questions people have in a larger home. I gave this thing 4 stars originally because of the lower power, but then UPDATED moved to 5 stars since it does so well for us. It looks awesome, sounds good, small, light weight. Most people in reviews talk about showers. Well our household take primarily baths. For filling a bathtub, you need to play with the settings. At 48 degree F water here in MI, I found turning water heater down to 1.5 gpm works. I set the temperature at 131 degrees at the water heater. By the time it gets to my huge Jaccuzzi, it goes down to 115 degrees. That is hot, so I was able to add a tiny bit of cold and got a Jaccuzzi tub full at 97 degrees in about 30 minutes. Not too bad. Plus it is hotter and can fill to any higher level than my previous 50 gallon water heater.Next test, a regular small bathtub, but at the far end of my house. The water lines run through the garage ceiling. By the time it gets there, it is at 106 degrees and takes about 10 minutes to fill the tub. This small tub actually was the hardest to get just right. Originally I had the water at 2.4 gpm, and it was fine for the big tub, but terrible for this far smaller tub. This is why I set the flow to 1.5 gpm right at the water heater. I think I will just leave it there, rather then keep having to adjust. Ok, 1.5 gpm is really low and 2 people cannot fill a tub at the same time, but it works for us and you can fill the 2nd tub immediately after. For your closer bathrooms, you can get a bit more gpm by adding some cold water. We had a 50 gallon direct vent gas water heater. This was not perfect either. We could never get more than 1/2 a tub before cold water started coming out. So even though this tankless water heater takes a longer time to fill a tub, it can keep going until it is full. So we just set the timer on the Jaccuzzi to 20 minutes and then come back and check on it. Compromises but the benefits are how efficient it is, how it never runs out of hot water, and since it is lower power, it has to be safer. It is safer than having a tank, that is for sure. Check water heater mythbusters on yout.So I am not necessarily recommending someone with a 4000 square ft house to buy this. Although for a conservative family that has no problem with compromising a little time for filling a tub for efficiency, you can definitely get by.Next test, faucets. You can run 2 faucets at the same time at my settings. I imagine at 2.5 gpm maybe 3 faucets but I do not want to keep changing the flow rate.I really love the touch screen and the looks are nice. Btw plan on a dozen trips to buy pipe parts. I also bought more exhaust vent. The exact same. Basically China makes these vent kits the exact same size so I can extend mine. Under 20 bucks online.Also plan on spending another 300 bucks on pipe parts. This is because you have to get the pipes from where your tank water heater was to where your tankless water heater is. I think it is worth it. It will save $250 a year. Btw, it felt good getting rid of that big bulky and ugly tank water heater.7/6/2017 Update: I just want to add that as the summer comes, I was able to lower temperature on the water heater to 113 degrees. So in the summer this thing has extra capacity available. I still just leave it at 1.5 gpm. Use of this water heater has become normal for us.