Summary:

Install a hybrid water heater with a minimum 10 year warranty instead of spending the money on a tankless water heater.

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All the Facts:

As per the Department of Energy‘s chart above, water heating accounts for 18% of a home’s energy use so getting this right is important. There is no question that an electric water heater is better than a water heater that generates heat through burning fossil fuels in terms of lowering emissions since 30% of grid electricity is emissions free. When using electricity, there are two main options for hot water, tank and tankless styles. The best in each category is point of use (POU) for tankless, and hybrid for tank style. Between the two, the hybrid water heater maintains the edge over tankless in several ways. Here is the pros and cons list for each.

Tankless POU Electric Pros

  1. When located at point of use, will reduce standby and distribution losses to zero.
  2. Provides infinite and instant hot water
  3. Requires almost no space to install

Tankless POU Electric Cons

  1. Instant hot water means you can not effectively pair with a solar array without net metering
  2. Requires a large amount of electricity which will likely bump up the required service panel size
  3. Less than half as efficient as a hybrid in heat pump mode (making the lack of standby losses irrelevant)
  4. Maximum energy factor (EF) only reaches around 0.95 (theoretical max for this style = 1.0)
  5. More expensive to install than tank because one is required at each bathroom plus the kitchen
  6. Electricity time of use shifting is impossible without installing a large battery system

Hybrid Pros

  1. A tank can act as a thermal battery
  2. Hybrids require a lower energy draw than tankless
  3. Hybrids in heat pump mode are two and a half times as efficient as a tankless
  4. Hybrids pair well with home solar even without net metering
  5. Many hybrids are WiFi compatible
  6. All hybrids make sense pairing with timers
  7.  Act as a supplemental air conditioner in the summer time
  8. Energy factors (EF) can reach 2.45

Hybrid Cons

  1. You will have standby losses; minimize these by decreasing piping runs
  2. Acts as an air conditioner in the winter time if you do not switch to resistance only heating, switching not required if you home has space heating from a heat pump.
  3. Over sized tanks are needed compared to standard water heaters if you always want to use the heat pump setting.

 

How do I decide?

You may take a look at the lists above and say, that there is a good amount of pros and cons for each, so how do I make a decision? The ultimate choice is fairly straight forward. Here are the points that drive that home. Hybrids are cheaper to install and at 2.45 EF for hybrids versus 0.95 for tankless heaters, the energy efficiency of a hybrid is 2.5 time higher. Since a hybrid also acts like a supplemental air conditioner in the summer, you will decrease your air conditioning costs and your water heating costs. If utilities move to a time of use fee structure for electricity, as California will in 2019, then hybrid water heaters will provide another benefit in that they can act as a thermal battery, heating the water when electricity is cheap, and providing it any time of day. For those of you interested in making use of the thermal battery option, always go with at least one size larger tank than you would for a standard water heater. For instance, if you were using a 50 gallon tank on your natural gas water heater, you should move up to an 80 gallon tank on your hybrid water heater. That way, if you put in a solar array in the future, it can warm the entire tank during the day which then becomes available water heat all evening long.