3 Things About Tankless Water Heaters

1. Tankless water heaters require a certain amount of water pressure. If the hot water pressure in your bathtub is bad, the tankless heater will not turn on. When you were signing up to buy one, you mentioned your bad upstairs water pressure to the salesman, and he said that oh, it's fine, people have really bad water pressure in Europe. Guys come to install your heater but you can't get any hot water in the shower because of the low pressure. You will have to call a plumber tomorrow to have him address your pressure situation, or (as a stopgap measure) you will have to run hot water in a sink that has good pressure in order to fool the heater into turning on. This, however, will mean that you'll only get a trickle of hot water into the shower, since you're competing with the sink.

2. When the tankless water heater installers are done, they'll show you their work and will tell you how to work everything. You will mention to them that you smell gas (referring, of course, to natural gas, not to "water heater installers had sausages for breakfast" gas). They will say that they don't smell anything and that it's just residual. An hour later your head hurts and you leave to run an errand. An hour after that you come home and open the door and think "Whoa! Stinko!" and your head and chest start to hurt almost immediately. You go check on the cat to make sure she's not a goner. (She's hanging out by an open window upstairs, smart kitty.) An hour after that the installation company sends a guy who finds two leaks along the gas pipe that the other guys had been messing with, plus discovers that the installers didn't relight the pilot light in your ancient furnace (probably because they'd never seen a furnace that had to be manually relit).

3. A tankless water heater looks sort of like a gym locker hanging on the outside of the house.