Should You Buy a Tankless Water Heater?
Pros and Cons
The mechanics of a tankless water heater may seem puzzling, but purchasing one might be your next best investment. If you’re shopping for a water heater, learning more about this option can help you decide why it may—or may not—be the best fit for your home.
What is a tankless water heater?
Sometimes called on-demand water heaters, these appliances provide hot water only when needed. When you turn on a hot water tap, cold water flows into the heating unit where a gas- or electric-powered element warms the water. This creates a constant supply of hot water without the need to store it in a tank.
Pros
A tankless water heater features advantages worth consideration. Here are a few:
Energy Savings
Unlike a conventional hot water heater, an on-demand unit doesn’t need to maintain the temperature of a large water storage tank, saving long-term energy costs. A gas-fired tankless heater that meets ENERGY STAR® specifications will save a homeowner an average of $108 each year, according to the U.S. Department of Energy.
Constant Hot Water Supply
You’ve most likely experienced that cold splash of reality that comes when a conventional water heater runs out of hot water. One advantage to installing a tankless water heater is that when it’s supporting a single appliance, it’s able to supply an endless stream of hot water. (More in a bit on the ability to run several appliances at once with an on-demand unit.)
Space Savings
On-demand water heaters take up far less space than the conventional type, which requires space for a tank that may hold up to 70 gallons of water. Tankless heaters are relatively compact; for example, a typical unit might measure 20” wide x 28” high x 10” deep. This smaller footprint makes the tankless water heater ideal for homes where space is at a premium.
Long Life Span
Conventional water heaters have a lifespan of about 10 years, 13 if you’re lucky. In contrast, a properly maintained tankless water heater may last up to 20 years.
Cons
Despite its benefits, this type of water heater isn’t right for every home. Here are a few disadvantages to consider:
Multiple-appliance challenges
Because the water is heated on demand, tankless units can’t always supply enough hot water if you’re simultaneously running several appliances, like a dishwasher and a washing machine. Some homeowners overcome this obstacle by installing two tankless water heaters or installing one for each appliance.
Initial Cost
Expect a tankless purchase to cost more than a traditional water heater—in some cases, up to three times more. In addition, older homes may require an electrical upgrade before installing an electric-powered on-demand water heater.
Long-term Maintenance
Like their tank counterparts, tankless units require maintenance and should be flushed once each year to remove sediment, minerals, calcium, and other materials that can sludge up the system. What’s more, they contain fans and filtration parts that require regular cleaning. Experts recommend hiring a water heating professional to perform these maintenance tasks, particularly since DIY maintenance voids some product warranties.
High Gas Pressure Required
The high-powered burner used in a gas-based tankless unit can require up to 150,000 BTU to heat the water, which can be a problem in a home with a low pressure main gas line.
Protect Your Investment
No matter what type of water heater you install, safeguard your investment with a Landmark Home Warranty. All of our warranty plans cover repairs and, if needed, replacement for conventional and tankless water heaters, so you can worry less about coming up with extra cash when something goes wrong.

More Resources:
http://energy.gov/energysaver/tankless-or-demand-type-water-heaters
https://www.angieslist.com/articles/what-are-pros-and-cons-tankless-water-heaters.htm
http://www.apartmenttherapy.com/pros-and-cons-of-a-tankless-water-heater-176538