IMO a home that size should normally have 2 heaters. If you opt for a single heater,at least make it centrally located regardless of type.

Do you have any high use fixtures (soaking tub, multi-head shower)?
I think you want the 65 at a minimum. A 50 gal electric heater is reasonable for a smaller house. 50 gal would work for the two of you. It would not work for much more than that.

This water heater can use the heat pump (very high efficiency) or the electric resistance heat (expensive to run). The heat pump is slow recovery - if it's being pushed into recovering quickly it will turn on the resistance elements.

A standard electric water heater costs about $450-500 a year to run. A hybrid costs about $125 if it's not kicking on the resistance elements often. You will recoup the $200 difference between the two if you don't force it into quick recovery mode by buying a heater that's too small.

Thank you all for your help! I think we will buy the bigger size :)

We have the GE GeoSpring Hybrid and are perfectly pleased with it. I'd select the size based upon number in household and whether or not you prefer a bath over a shower. If it's just the two of you then the 50 gallon should be fine.

Hi oneandonlybobjones, I don't really agree with that chart based on my own experience. What I know is that gas has a first hour rating that's higher than electric.

Generally, unless you are talking POU, you are talking a minimum of 40 gal gas or 50 gal electric / hybrid. If you have 2 members of your family getting ready for work/school at the same time that minimum will work.

If you have additional family members who get ready for school/work at the same time you will need more than that or you will have times when there is not enough hot water.

It's really about how many people use hot water at about the same time. For example: 3 people taking 10 minute showers would use about 67 gal of hot water (assumes 2.5 gpm, 130 tank temp, 60 cold water temp, 105 shower temp). That's the first hour rating for a 40 gal gas 36k btu water heater. Note: if the showers were roughly at the same time (not over an hour) it wouldn't last even that long. Also note that's not any additional use - such as shaving, laundry, kitchen sink, etc.

A 40 gal electric will produce 51 gal of hot water in the first hour - so would not provide all of the hot water for 3 people getting ready for work / school. A 50 gal would provide ~62 gal - again, not quite enough for 3 people.

Hi Jake, Lowe's has a chart that's similar to Home Depot for sizing water heaters, 3-4 people = 50 gallons, 5 + people = 80 gallons. Once you click on the Lowe's link, then just scroll down to the "Capacity" section to see the chart. Rheem also has a similar sizing guide, 3-5 people = 50 gallons, 5 + people = 60 gallons or bigger. Once you click on the Rheem site link, then just scroll down to step #4 and pop open "Tank Type" to see the chart.

Maybe the charts project kids taking a bath at night and adults in the morning? Maybe they estimate showers that are shorter than 10 minutes on average? That might explain the difference between your calculations and the charts. Anyway, I just thought I would let you know that I checked a few other resources for water heater, sizing information and, for the most part, they agree with each other. I think Abby made the correct decision to go with the 65 gallon size.

Hi oneandonlybobjones, I'm not saying you are wrong, and I really do appreciate that you have support for what you are saying. My guess is that they are all referencing the same information.

What I saw was that they were assuming an 8 minute shower. What I didn't see in the original chart was a differentiation between gas and electric even though gas has a much faster recovery time - and therefore a higher first hour rating. The Lowes chart splits them out. I stand by my math and my math matches my personal experience as well.

I don't normally see less than 40 gal gas water heaters. Likewise, the typical electric heater is 50 gal min. Looking at pricing on Lowes, the 30 gal gas costs $70 more than the 40 gal.

Re-reading the original post, it looks like the hybrid is using both the resistance elements and the heat pump to achieve a faster recovery rate and thus a first hour rating of 66 gal for a 50 gal tank. That puts it very close to a 40 gal gas. Assuming that they will have the house and the water heater long enough for the intended family, I think the 65 gal is the right way to go and will also limit the amount of time using the resistance heat to recover.