They SEEM like a good idea. On the down side, they are expensive to install because they use larger electric service to supply a large amount of electricity in a short time, or they use larger pipe sizes for gas. A water heater input is usually 5 kw at a time or 40,000 btuh gas; but a tankless has no storage so it has to have much more electricity or gas immediately.

Gas burners are now modulating, so include complex electronic controls beyond the scope of many repairmen; just look at the posts on the net about this type. Installing an instant water heater yourself at $700 per – not including the gas or electric service can be daunting compared to a $250 water heater replacement like-for-like. This is an area where people who haven’t a clue about what the word efficiency means get into technical jargon beyond their scope and believe the marketing salesmen who often haven’t a clue as well.

Most areas of the world have high comcentrations of hardness; few have water as soft as New York, so the inside of the instant heaters clogs the small tubes and gas regulators with lime in a few years. Europeans are used to having their units disassembled and refurbished every year; but Americans are used to buying their heaters and forgetting to maintain them, so the units die in a shorter time than most tank type heaters.

Keeping a log of 10 years of tank-type heating and instant heating, it may be hard to find a savings when including installation, reinstallation and service bills. As there are tank-type heaters in the 94% efficiency range now with high insulation surrounds, the tank-type may prove more economical and less worrisome.

There is a place for a tankless type water heater in a home where popping on a 25,000 btuh fire that can heat a small home heats a cup of water from the tap, or watching an electric meter whiz is entertainment, and where the owner will follow manufacturer instructions to rebuild the heater yearly by a pro. The more likely place for such is to heat a Jssacuzzi or drive several showers for frequent guests or large families where larger water heating loads are the norm. For houses where the two occupants use a shower once a day and do a laundry every few days and just drink water or heat a teakettle; the instantaneous is probably not the big money saver it is promoted as; yet, small incomes may make them seem attractive.