So My Water Heater is Pretty Old...

[jeff47]

1. I've had a gas tankless hot water heater

It worked about as well as the "tank" version. I wasn't even aware that they'd come out with whole-house electric ones.

The big thing to look out for: How many things can you run at once? A lot of the smaller units can't handle more than one or two faucets. And keep in mind when they brag about number of shower heads, they get to use the lowest-flow showerheads they can find. A dishwasher or washing machine use a much higher flow, and you'll have problems if it can't keep up with that.

Also, see how adjustable it is. I know of some electric tankless units that are meant to only heat up one shower or sink (think adding on a bathroom and not wanting to run a hot water line, or new bath veeeeery far from water heater). The drawback to some of those units is they only had two temperature settings, "warm" and "hot". This can make it hard to get a temperature you find comfortable.

As for savings, the gas unit was going to take around 7 years to pay for itself. Electric is going to be much harder to calculate, because electric rates are far more variable than natural gas rates.

To try and guess how long it'll take to "pay for itself", think about all the time the hot water is not used. Keeping that tank hot is all you are really saving. So if it's just you or you + 1 and you tend to use a lot of hot water at one or two times a day, then you can get some decent savings. If there's a lot more people in the house, or hot water demand all day long then it will be much harder to save money via a tankless system.

If you'd like a cheaper solution, put insulation on the outside of the water heater and any hot water pipes you can get to. There's kits available at your local hardware store that make it pretty easy.