FLSeaDog, ideally, the temperature should be adjusted precisely for each person. However, realistically, no. Hopefully all the preferred bathing temps fall within about a 10°F range ... so perhaps adjusting the unit between a lower bathing temp (perhaps 108°F to 110°F) and a higher household use temp (120°F to 125°F) would be a workable compromise. Ten to 17°F difference doesn't seem like much, but for a tankless that must heat a flowing volume of water on-the-fly, it can be enough to justify. Of course, frequent adjustment certainly can be an inconvenience to the point of being unworkable if the unit isn't easily accessible. This is where remote controls come in handy. My unit is in a broom closet in my laundry room. I leave it set on 104°F as the "normal" setting, raising it as needed for washing clothes (open the closet, punch a button a few times, it automatically drops back down after 30 mins) ... or sometimes lowering it a little for a cooler shower in the summer heat. I don't raise it for dishes, as my dishwasher has built-in water heating. Maybe I've become accustomed to my tankless and using it efficiently to the point of unconscious habit ... but I have no complaints. I have to wonder if the folks having trouble just are unwilling to modify their usage habits accordingly, or if there's something wrong with their installs, or the units involved just don't work very well.

Is 15A 120V breaker all that is needed for the electrical requirement on a gas tankless? Or does it need to be 20A? I believe there is some open slots in my panel for a new breaker, and the panel is only about 15 feet from where the unit would go, so running a new one isn't too big of a deal. The unit would be going on the exterior wall that is part of my garage, so a new electrical run could be ran through the attic, down on the interior of the wall inside the garage, and then drilled through the wall and an electrical box placed on the exterior. Or, it can be ran through the attic and down through the soffit and ran through exterior grade conduit on the exterior wall of the house. Which one of these would be approriate? If running down the exterior wall in conduit, where does the conduit need to start? Just somewhere up in the attic, but it doesn't matter where? I know that code in this area does not require full length of electrical runs to be in conduit Lastly, is the electrical connection from the gas tankless hardwired in, or is it an actual plug? The reason I ask these questions is that I have 2 quotes and one of the plumbers doesn't do electrical so I have to source it out, and the other plumber does, but he is the one who said he'd tap the GFCI. They also wanted to charge me $300 to tap the GFCI, run 2 ft of cable, drill a hole, and mount a box, and that is just absurd, so I'd probably do the electrical myself or have my handyman do, it is far cheaper.

Have to disagree with GreenDesigns who states, "they offer almost zero improvement in efficiency of a new high quality tanked electric heater. ...electrical tankless is only truly practical if designed for a new build from the beginning. Retrofitting is extremely expensive and won't give you a payback for the cost differences inside of your lifetime." I put a whole-house electric tankless in my 1906 house and will never store water in a tank again. Absolutely love it! It's mounted on the wall, directly to the side and just above the dryer. I did not bother to hide the water lines inside the wall, but since they're [mostly] hidden by the dryer, who cares? Sometimes, putting plumbing pipes in the wall is highly overrated. Mine is in the bath/laundry room and I've never found it to be unsightly. Yes, the tankless requires quite a bit of power: Mine requires two, double-pole 60amp breakers with 6g wire. So, here's where distance from the electric panel is a cost consideration.

Hi bold_as_love. I'm not sure I followed anything you said past "PV". Ok, so let me be clear - there are cases where Point Of Use electric tankless makes sense to provide instant hot water in remote locations. There is virtually no case where whole-house electric tankless makes sense. The amount of current required for a whole-house electric tankless can run 180 amps with at least a 300 amp service. That kind of current almost always means significant upgrades to the electric service. Even then, electric tankless will struggle to provide enough hot water. The savings for Electric Tankless are only about 2-3% over a standard electric tank. Very little standby heat is lost through the insulation on a tank electric heater. An electric tankless heater (or electric tank heater) is NOT something you would ever want to pair up with PV. What is paired up with PV is the hybrid heat pump water heaters. If you look at the energy sticker on a standard electric water heater they will show about $420-500 a year. A tankless electric will be a couple percent less. A hybrid heat pump energy sticker will be ~$110 a year.