Tankless Water Heater Pros & Cons

9 06 2013

Tankless Water Heater

Although tankless water heaters provide unlimited hot water throughout the day, there is a limit to how much hot water the unit can generate at the same time. Therefore when buying any type of water heater, tankless or not, it’s crucial to estimate PEAK DEMAND, i.e. how much hot water is used at the same time. Larger homes may require multiple water heaters.

For example, two or possibly three people might take showers or baths in separate bathrooms around the same time — typically in the morning — plus a washing machine and/or a dishwasher. Even a small whirlpool or soaking tub requires a significant amount of hot water.



  1. Plenty of hot water (no more sudden cold showers; great for filling large Whirlpool/Soaking Tubs)
  2. Saves energy (uses gas only when hot water is needed)
  3. Saves money (cut our gas bill in half because not continuously heating a large tank of water)
  4. Space saving small wall mounted box
  5. No ugly vent pipe (when outside)
  6. No enclosure to buy or build


  1. More Expensive to buy (but over time energy savings can offset higher cost)
  2. Uses more water (water must run for at least two to three minutes to heat up in addition to travel time from unit to faucet. e.g. our shower is 20′ from the unit and it takes 3-4 minutes before getting warm water.)
  3. Noise (AVOID installing on an exterior Bedroom Wall.) [When anyone uses hot water while we are sleeping, it wakes us up. BTW – The unit we have sounds like a printer.*]

Tankless Water Heater

                  **** TIPS ****

Locate any water heater as close as possible to bathrooms.

Consumer Reports has a calculation chart for storage tank water heaters that calculates gallons per minute (gpm) to help determine what size tank you need.


*In the photos is a Rinnai tankless, which has an attractive stainless steel case. For more information – http://www.rinnai.us/customer-care/support-faq

Other tankless brands include Noritz, Rheem, Jacuzzi and Bosch among others.