The Hybrid Water Heater – The high tech, high efficiency replacement for on-demand water heaters?

The hybrid water heater revolution...

The on-demand tankless water heater has been widely accepted as the answer to efficient residential domestic water heating lately. Eliminating the holding tank and the associated energy loss from water heater design does make intuitive sense.

In practice, some consumers have complained that on-demand systems deliver annoying cold water slugs and long water-wasting delays as the system responds to water demands in the home. Others with unusually cold ground water sources have had problems with inadequate heat rise performance with tankless models.

To be fair, many have been perfectly happy with their decision to go tankless, but a newer technology is making the holding tank style water heater worth a second look.

The hybrid water heater mixes two technologies, standard electrical resistance water coils, and the air source heat pump to create a new product class with remarkable energy-saving performance (in the right situation).

Air source heat pump heating and air conditioning systems are known for excellent energy performance when in heat mode because the units move and concentrate thermal energy rather than produce thermal energy from a combustive or resistive fuel source. Moving thermal energy that already exists in the atmosphere is far less energy intensive than producing heat with a resistive electric coil.

Essentially, heat pump water heaters are highly insulated water tanks with a condenser unit sitting atop. The condenser concentrates thermal energy found in the ambient air surrounding the unit, depositing the heat energy into the water tank.

If the ambient air surrounding the unit is not of adequate temperature, or if hot water demand outstrips the condenser capacity, resistive coils provide backup heat (at significantly greater energy expense).

Hybrid water heater or heat pump water heater designs are boasting energy performance statistics that are truly remarkable. The GE GeoSpring Hybrid Water Heater boasts an energy factor (EF) or 2.3, compared to a current minimum EF of 0.89. At an EF of 2.3, the GeoSpring is one of the most energy efficient water heating options currently on the market, if you have the right situation that will allow the unit to operate at this level of efficiency.

GE claims that their GeoSpring unit will consume 62% less energy compared to a standard electric water heater. A careful comparison of fuel costs based on local electrical rates and natural gas fuel rates would be necessary to fully appreciate the best fuel option for your area, should you have gas available.

Even if you live in an region where a heat pump water heater is appropriate, it still may not be the economical option given you local utility rates. Do your homework!

The Downside to a Hybrid Water Heater

A heat pump water heater requires a significant quantity of ambient air from which to draw thermal energy. Figure a requirement of 1,000 cubic feet of ambient air.

Also, since these units move heat from one spot to another, homes in cold climates may require the units to be installed indoors. That means that the unit will be borrowing heat produced by your furnace in order to heat the water. The unit will then blow cold air out into the room, essentially behaving like an air conditioner. That cold air would then need to be again warmed by your furnace.

The fuel costs associated with heating the air used by the unit are not factored into efficiency statistics.

Here are two product information videos produced for the GeoSpring line:

How A Heat Pump Water Heater Works

GE Hybrid Water Heater Product Demonstration

The Hybrid Water Heater Bottom Line

A heat pump water heater may be a viable option in high efficiency domestic water heating if you can place the unit in an area with adequate naturally warmed ambient air from which the condenser can rob heat.

If you live in an area with a colder season and must pay to heat the ambient air used by the condenser in these units, you will likely be better served by either a tankless water heater, a high-efficiency tank-style water heater, or better yet, a solar thermal water heating system.

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