Reply To: Heat Pump Water Heaters – GE vs. Rheem

The Tank Heat Pump Water Heaters – GE vs. Rheem Reply To: Heat Pump Water Heaters – GE vs. Rheem


Schieftain wrote:

Would this unit lower the surrounding air temp below the 45 degree threshold and put it into standard electric mode? If so, what’s the EEF in that mode?

Hi Schieftain, I had some similar concerns before I purchased my GE unit (I live in Iowa). I emailed GE and this was their reply. Hope it helps. My questions are in black. Their replies are in blue.

I live in eastern Iowa (about three hours directly west of Chicago). It gets really cold here in the winters, as you can probably imagine. While I know that the GE Hybrid Water Heater will be much more efficient in the warmer months for me, I’m still concerned about the winter. The ambient air temperature in my basement this morning was in the upper 40s, possibly as high as 51 degrees (depending on which thermometer I was using). According to GE, the heat pump component of this water heater will work down to 45 degrees. But, I’m assuming that there is a rate of diminishing returns here, correct? Or am I not understanding how the technology works? You are correct. The heat pump will operate down to 45F. Below 45F, the unit uses electric resistance heat elements, and the efficiency is similar to a st andard electric water heater. Above 45F , the heat pump efficiency is related to the ambient temperature. But, even at colder ambients (45-60F), the efficiency is still much better than running in standard electric mode.

If my basement were to get cold enough that this water heater had to work in Standard Electric Mode, can you tell me how efficient this water heater is in this mode? In other words, a highly efficient traditional electric water heater might have an Energy Factor of .94 or .95. How does this unit compare if operating purely in standard electric mode? A standard electric water heater typically has an EF in the 0.88-0.90 range. The GE Hybrid water heater has an efficiency of 0.89 when running in st andard electric mode. Therefore, when running in standard electric mode, the unit has an efficiency just like a standard electric water heater. As you state above, some higher efficiency electric water heaters can achieve EFs of 0.92-0.95, but these units tend to be more expensive than standard electric water heaters without providing a significant increase in efficiency.

When the Energy Factor of 2.35 was calculated, what temperature ranges were used for that calculation? Given my winter basement temperatures, I’m guessing that the Energy Factor in my situation will be significantly lower, correct? Official EF testing is based on the Department of Energy test procedure and is run at 68F ambient temperature. As ambient increases, EF increases, and as ambient decreases, EF decreases . Based on our internal testing at GE, the GE Hybrid water heater’s EF ranges from approximately 1.8 at 45F to 3.2 at 120F. A 1.8 EF means that the unit is up to 50% more efficient than a standard electric water heater. A 3.2 EF would be up to 72% more efficient than a standard electric water heater. These are NOT published values, but are provided for guidance only.

Finally, with a winter basement temperature in the upper 40s to lower 50s, can GE provide an estimate of how efficient this unit might be during the winter months? Using the info provided in the above answer, the EF of the GE Hybrid water heater will be approximately 1.8-2.0 when ambient temps are in the upper 40s to low 50s. Therefore, at these ambient temperatures and EFs, the unit should operate between 50-55% more efficiently than a standard electric water heater that has an EF of 0.9.

Cheers, Bryan

Water Heater Rescue

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