Yes, I do have thoughts: Don't go with an electric tankless.

Electric tankless doesn't get you any savings, and is very expensive to install the electrical service to make them work.

What is it that you are trying to achieve by going tankless (Energy savings, space savings, or continuous hot water)?

Tankless water heaters have their virtues, but electric ones have significant wiring needs. A small electric tankless like the Ecosmart Eco 18, which can supply 2.3 gpm in an area where the groundwater is 52 degrees F, requires two, 40 amp double pole breakers, and 8 gauge wire. A larger electric tankless will require even more, including possible 3 breakers and even heavier wiring. You also have to remember that, the colder your climate, the colder the inlet water temperature will be: as a result, colder climates require bigger amperage tankless heaters to provide adequate water.

Jake-

I will point out that a water saver showerhead only uses 1.5 gpm, so it is doable...but not much else can be happening at the same time. I also agree that tankless heaters make more sense as part of a combi system or heat pump system... and/or if natural gas is available. And I didn't want the OP to think that she could just install one and plug the cord into the wall like a toaster ;-)

Kudzu, similar to you not wanting the OP to think she could just plug the cord into the wall, I want to be clear about the water flow. A 2.5 gpm shower head is a "water saving shower head" and is the standard flow rate that we use to design water heaters. Moving to a 1.5 gpm shower is extreme and something much less than what most people expect. I think it's disingenuous of these water heater manufacturers to claim that they can supply a shower and a bathroom sink, even though they spell out that it's with a 1.5 gpm shower head. It's a little like saying a can of pop is 200 calories per serving.... oh, and there are 2.5 servings per can.

As you know from my previous posts, I'm pro-resource conservation. At the same time, I don't want people having unrealistic expectations. A whole house electric tankless saves only 2-3 percent over tank electric. There are sometimes compelling reasons to use electric tankless, but not often.

Whether or not a tankless unit can service a 2.5 GPM shower depends on the desired temperature at the shower. If the unit is outputting 120°F (or higher) ... most people don't run their shower that hot so cold flow is mixed in at the tap which reduces the hot flow, effectively increasing capacity to support a concurrent task.

Skin surface temperature is normally around 91°F to 93°F so water temp higher than that feels warm. I rarely run my shower higher than 102°F, which clocks my tankless at much less than maximum output. On the other hand, filling a bathtub/whirlpool tub for soaking with 102°F water loses some heat to the mass of the tub, barely feels warm, and quickly cools.

dadoes-

You're correct about the various temps. The example I gave in regard to a particular electric tankless was for a groundwater temperature in a moderate climate (like the Pacific NW) where it's about 52 degrees F. The specs for that heater say it outputs 2.3 gallons at 105 degrees F, which means it would actually be putting out about 1.8 gpm at 120 degrees F; that temp would obviously would burn you in a few seconds unless it was mixed down to at least 105 degrees F, which is at the high end of how hot one wants a shower to be. I actually have well-designed, low flow showerheads that demand about 1.5 gpm -- and that I am satisfied with -- so I would be fine with that size tankless unit as long as I wasn't running two shower heads at the same time, or had a large, competing demand for hot water from something like a dishwasher or clothes washer.

People who are considering a tankless unit need to be aware of: 1) the total demand for hot water that could occur at any particular time, and 2) the lowest groundwater temp in their area. If you live in Florida, a particular tankless heater will provide a lot more hot water than if you lived in Maine :-)

I see conflicting information on hybrids as well. Some rate GE as great, but there are articles saying they will stop being made. Plus it says something about a drain. I have a slab, but could I put a drain low on an exterior wall?

dadoes: When we size water heaters we use 105 as the output temp. We use 2.5 gpm for a shower, 1 gpm for a bathroom sink, 2 gpm for a kitchen sink and ~4 gpm for a traditional tub. These are pretty standard numbers to design around. And it doesn't matter if the water heater is outputting 120 degree water and mixed down to 105 or outputs 105 - the result is the same.

Patricia Harrington: The hybrid water heaters are in their second / third generation - so they are still a little new, but much more reliable than the first gen. I think that the GE Geospring has been discontinued and replaced with a newer model. They do need some space around them (basement or garage, for example) and they do need to drain condensation. You can drain to an exterior wall if it won't freeze. You can also install a condensate pump. How does your air conditioner drain? Where does your T&P valve on your current heater drain to?

You should know that many power companies / states / localities offer significant rebates on these hybrid water heaters. I think there is a federal tax credit of $300 as well. The Energy Guide on these show that they cost ~$150 a year to run vs ~$550 a year for a standard electric. After rebates and tax credits they end up paying for themselves in about 2-3 years - that's pretty great.

Tax credit ended 12/16 :(. Ac is in garage and has pvc pipe to drain outside. I think water heater will need to stay in laundry room as that's where pipes are. Would love to put in garage which is only for storage as built incorrectly .

Good to know about tax credit, thanks. Check on the rebate though through this website. Have seen some as high as $500.

If your laundry room backs up to your garage, I'd look into the cost of moving it into your garage - esp if you are in a warmer climate and your garage is insulated (won't freeze)

It could drain the same way your washer drains.

GE sold their manufacturing equipment for the Geospring hybrid water heaters to Bradford White Water Heater Company. Bradford White will continue to make the hybrid water heaters. They also are handling any warranty issues for the Geospring water heaters.

Patricia Harrington: Note that the Geospring isn't the only player: Rheem has a unit available through Home Depot.

I am going to get a plumber out to install either a regular or hybrid. Fortunately it's not urgent, and I am doing renovations anyway

I agree that tankless electric is not a good choice if your current electric service was not designed for it. Just use a 40-50 gal electric unit, insulate it, and put it on a timer that shuts it off during the day and at night.

Also, if you are looking at a hybrid, make sure you have a big enough room to install it. Most of them require a room volume of about 700-750 cu ft to operate (a 10'x10'x7' room). If your current electric water heater is in a closet it is not likely to be big enough for a hybrid.

Bruce

Most homes have electrical service 200 amps and less

I would say most homes have 100A and less. New construction yes 200A but older homes are lucky to have a new panel at 100A. Some still have the fuse boxes. Hard enough to pull off electric tankless with 200A and impossible with 100A.

Which water heater did you choose?