Advice from Angie's List by Angie Hicks: Tankless Water Heaters
"A tank water heater is a variable-temperature device," said Ed Clark, owner of Tankless Concepts in Falls Church, Va., which has installed more than 1,000 tankless units over the past nine years. "When you turn on the hot water and hot water is flowing out, an equal amount of cold water is brought down to the bottom of the heater and mixes with the hot water you just paid to heat. This is a situation we've accepted for many, many years, but there is something wrong with this picture."
"We have a number of heaters we've put into four-story townhouses, which have an 80-gallon tank on the top floor, which is like a ticking time bomb ready to send water down four stories," Clark said. "A tankless heater replacement solves that problem and prevents that from being such a big liability."
"An extremely high percentage of (the service) calls that we go on are because of improper installations," Clark said. "There are a whole bunch of people putting them in that do not install them correctly. Probably the biggest factor that causes the most damage is the fact they don't have a condensate collector properly installed. So any condensate that forms inside the venting system runs back into the unit. It's very discouraging to see a unit that will last 20-plus years if properly installed being completely degraded by the condensate they didn't see fit to collect."