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Fuquay Varina, North Carolina, United States
A guy finding out if life really does begin at 50.

Saturday, November 1, 2014

GE GeoSpring Hybrid Heat Pump Water Heater

GE GeoSpring
Our new GE GeoSpring Hybrid Heat Pump Water Heater has been installed and operating since 1pm on October 2, 2014.  I've had an energy monitor measuring the kWh the GeoSpring has used since it was first installed and turned on. That same energy monitor was installed on the old water heater that the GeoSpring replaced, so I am able to compare the energy used by the two water heaters.

I have been resetting the energy monitor the 1st day of each month since March of this year (I installed the energy monitor in February).  The old electric 'storage tank' water heater energy is shown in the chart below for the months March through September.  The new GeoSpring energy starts in October. The drop in energy usage for October is noticeable (138 kWh vs 318 kWh average). At 10.5¢ per kWh, the GeoSpring monthly energy cost was $14.48 vs. $33.41 (average) for the old water heater. The result is a savings of $18.93.

The downward trend in April, May, and June I believe is as much due to an increase in the input (ground) water temperature, as any decrease in hot water usage. The ground water temperature is still quite cold in March and warms as the days warm. The increase in hot water usage in July and August then leveling off in September I think is the water heater leaking. The leak was at the top of the tank where the pipes thread into the tank. So all the water that leaked out was heated.

The temperature of the air in the crawl space in October was always above 65 F.  In November the crawl space will cool as will the ground water temperature.  The heat pump is used to heat water as long as the crawl space is above 45 F.  I'm expecting in the latter half of November that the crawl space will be below 45 F, and stay that way until late March.  During the cold weather months, the GeoSpring will use the 4500W element to heat the water, so it should perform similar to the old water heater it replaced.

I'm very happy with the performance and energy savings of the GeoSpring.  Maryann likes always having hot water again.  I had a timer on the old water heater, and often when she wanted hot water, there was none. She has noticed that we have used all the hot water the GeoSpring tank holds at least twice, but in both cases, she noticed it during her shower which was right after the two boys had taken theirs.  The GeoSpring has a 65 gallon first hour rating, so we adjusted the shower order to hers first and the boys get whatever hot water is left.  That may not be much...LOL.  Depending on how warm the crawl space stays, the only other adjustment in hot water use timing I plan to make is to run the dishwasher in the afternoon instead of after supper when everyone wants to take showers.  That'll make sure the water is as hot as possible when the dishes are washed.
01/01/2015 - Updated the chart with November (178 kWh $18.70) and December (201 kWh $21.18) usage.  The crawl space is now 53-55 F on average.  The savings is not as great in Nov/Dec because of the decrease in supply (ground) water temperature.  I didn't measure the supply water temperature in October, but I'm sure it was considerably warmer than the current January supply water temperature of 51 F.  Also there continues to be a high demand in the evenings for showers.  The high demand causes mixing of the much colder supply water (in the winter months) which causes the heat element to run longer to heat the ~51 F water to 120 F.  After showers the heat element typically runs for an hour to recover which is ~4.5 kWh.  Unless we can change our demand pattern the saving (vs standard electric) will not be as great especially in the winter months when the crawl space air and supply water are much colder.  I'm considering putting the water heater in heat pump only mode since the crawl space is staying above 45 F.  The heat element will not be used to recover which will save energy, but using just the heat pump will greatly increase the time needed to recover. 
01/03/014 - Pacific Gas and Electric Company Evaluation of the General Electric Heat Pump Water Heater Demand Response Module states "... heat pump that is approximately equivalent to a 1.5 kW element while using only 0.5 kW of power." (pg 5).  1.5kWh is ~5118 BTUs/hr. It also implies (Fig 9 pg 19) that the electric heating element is activated (and the heat pump disabled) with a 25 F drop in water temperature (if the thermostat is set at 135 F then the heat element will activate at 110 F).