Question: We live in Blue Sea Quebec. We are considering installing a geospring hybrid water heater. Our basement is 60-70% bedrock and can get very damp in the summer months. On hot muggy days the basement is rather cool. In the winter we keep the basement around 60F.

Will a geospring work as effectively in such an environment? Thanks.

Answer:

Thanks for the question. While a better answer might be solicited from GE, the manufacturer, I’m happy to offer my opinion as well.

GE Geospring Water Heater

First, some background… The GeoSpring claims to use 1,856 kW per year for a typical home (62% less than a standard 50-gallon electric water heater, based on DOE test procedures at a 68°F ambient temperature), which correlates to an annual savings of $320 at approximately $0.106/kWh energy rate.geospring

The water heater operates with a ‘dual fuel’ scenario that sends the ambient air through an evaporator to extract the heat and transfer it to the water. The unit also includes a backup heat source – electricity – programmed to take over if the stored water temperature falls below the setpoint (adjustable from 100-140°F).

Four operating modes are available:

– eHeat Technology
– Hybrid (factory default mode)
– High Demand
– Standard Electric

Each of these modes is explained in detail below. Note that energy performance, consumption and savings are based on Hybrid mode operation with a temperature setting of 135°F.

Modes of Efficient Operation

eHeat Technology: This mode is recommended for maximum savings and is the most energy-efficient mode for the GeoSpring. Heat is extracted from the ambient air to heat the water. Response time is slightly longer in this mode so it might not be sufficient for a high-demand situation.

Hybrid: As mentioned above, this is the factory default mode. It combines the energy efficiency of eHeat with the recovery speed and power of the Standard Electric mode with a quicker response time to demand. Hybrid mode allows the unit to perform like a standard electric water heater while still providing energy savings.

High Demand: This mode uses the electric heating elements only when the water demand is higher than normal, so it differs from Standard Electric since the electric heat is only intermittently used when necessary.

Standard Electric: This is the least efficient operating mode and uses only the upper and lower heating resistance elements to heat water.

Conditions for Optimal Use

The GE website states that if the GeoSpring is located in a “conditioned space” inside the home such as in a utility room, the cooling and dehumidifying effect of the hybrid will decrease the load on the AC system during cooling months (summer) and increase the load on the furnace during heating months (winter). Even though you’re keeping your basement at 60 degrees, this is still for all intensive purposes a conditioned space.

I couldn’t find specific information on this, but it stands to reason that the unit would operate more efficiently at higher temperatures. How much more efficiently…? That’s a little trickier (though again, GE engineers have no doubt performed these calculations already).

For the first three operating modes described above, the operating air temperature range is 45-120°F, with a Standard Electric mode operating air temperature range of 32-150°F.

My interpretation of this is that between 32-45°F the unit’s two electric heating elements are enabled as this is out of the heat pump operating range. Since your basement temperature is well within this range, I’d say any of the operating modes are applicable and as long as the unit is located according to GE’s recommendations (any common indoor area such as a garage, utility room, attic, closet, etc with free area equal to 10’x10’x7’(LxWxH) – though it can be located in smaller areas with a louvered door.

I did not see any references to recommended humidity levels in the product literature, so it seems this would be acceptable – though you might anticipate higher than normal levels of condensate.

CONTRIBUTING EXPERT

imageSarah Gudeman

Sarah Gudeman is a mechanical design engineer and licensed EIT in the state of Nebraska. Ms. Gudeman also is a LEED Accredited Professional (BD+C) and an active member of the USGBC Nebraska Flatwater Chapter’s board of directors. She specializes in building energy modeling and audits, sustainable design and environmentally-friendly practices.

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