I should note we have 320 amp electric service so big pulls shouldn't be an issue. Moreso just trying to find some units that can give that much of a temp rise with electric power. Most are only 40 degree rise I've seen unless they are gas. Open to point of use too, just not sure how many/what the overall system would look like.

well, this isn't great...

So first of all you should know that tankless electric is only 2-3% more efficient than tank electric. You aren't gaining anything efficiency-wise by going electric tankless.

Second, as your research suggested, it's tough to find a tankless electric that can do that kind of temp rise. Gas tankless are typically 200k btu / hour. A similar electric unit would be about 58.6 kw or would pull 244 amps at 240 volts. I haven't seen that size unit for residential. Most are topping out at 36kw. BTW: You can cut to the chase with electric tankless, - look for their kw rating. They all are working at about 100% efficiency - there's no magic.

A 36kw heater will do 4.1 gal a minute @60 degree rise and 3.3 gpm at 75 degree rise.

A shower head is 2.5 gpm and a tub is 4 - 5 gpm. At 65 degree rise, you could run 1 shower and 1 sink faucet at the same time. Granted, you could have 2 of these units -- but they would pull a total of 300 amps... as long as you didn't run your electric tooth brush at the same time... Kidding - you can't run two of them. My guess is that you are also heating your house and running other appliances (stove, for example) on that 320 service. You don't really have that much headroom.

I think you are looking at an electric tank heater. Marathon makes fiberglass heaters that won't rust - addressing your issue of water heater leaking. You would also have it installed on a drain pan.

There are some great hybrid (heat pump) heaters that cost less to run than 95% gas tankless, but I don't think it would work in your application because they need air circulation and they make some noise.

Thanks Jake. Interesting. Yes we considered a heat pump heater but there's the issue of space and noise and temperature effects. I think an electric tank will be very costly to run all the time. And I think I will never get to take a nice hot bath. So what about point of use units? I've heard people are really happy with those when they're installed right near the shower or under sink. Used allover Europe for years without gas....seems very functional. FYI, our showerheads are 1.75gpm-2gpm. Washer will have internal heater. Could we have one central unit that would get water to warm and then also install point of use ones to take the tankless water up to hot for showering? Yes the 320 amp service is for the whole house. We paid so much more for it under the guise of it "covering all the bases" so to speak. Like electric car-charging in the future, or things like that we might want down the road so I am disappointed to hear we aren't covered to heat our hot water with it. Darn cold colorado mountain water temps!

BTW: If you are interested - here are the numbers:

The definition of a BTU is the energy required to heat 1 pound of water 1 degree F.

A gallon of water weighs 8.34 pounds. So, it takes 8.34 BTU to heat a gal of water 1 degree F.

To raise it 65 degrees would take 542.1 BTU

To raise 5 gallons 65 degrees in one minute (5 gpm - enough for 2 showers at the same time) would be 162,630 BTU per hour @ 100% efficiency.

A kilowatt (1000 watts) = 3412.142 BTU/hr

So that would take 47.66 kw

47660 (watts) / 240 volts = 198.53 amps - or roughly 200 amps.

bdrhome: The electric tank and the electric tankless cost almost the same to run.
They are both virtually 100% efficient and the standing losses on a well insulated electric water heater are minimal. Seriously, only 2-3%. BTW: that heat loss is to the surrounding air. That means in the winter, it just contributes to heating the house a little bit and tank and tankless would be equal assuming you are heating the house with electric resistance heat.

The numbers don't change for a POU electric water heater (exact same physics and math). You don't ever get more BTU's per kw/h (unless you go with the heat pump).

Thanks for the number crunching. Sufficiently impressed! ;0

" I think an electric tank will be very costly to run all the time."

Point is, it doesn't run all the time. I have a fairly standard middle-of-the-road HomeDepot electric water heater set to about 125F. I have a power monitor on my electric. By direct observation, it might be active MAYBE 30 minutes a day, perhaps an hour.

I also have an insulation blanket around it which I used to have on the old tank. I don't think it really needs it since the temperature inside the blanket (measured by thermometer continuously) never exceeds 72F.