About 3 years ago I made the decision to convert from a gas burning hot water heater to a tankless electric unit. I picked out the system based on the size of my house (4 bed, 1.5 bath) and selected a place in the basement central to the distribution to the kitchen and 2 bathrooms. Checked that my electric panel would handle the 3x20A breakers it would need and then asked my plumber to install it.
He said no. !!!
My plumber said – you’ll be asking me to replace it next winter. If you had well water, which comes into the house at a reliable 55 degrees, that would be OK. Then your tankless system will only be trying to raise the temperature of the water about 60 degrees. But with public water coming from the street provided by Aqua, the incoming water temp is likely to drop into the upper 30s in the winter coming through distribution pipes from the town water tower. My unit will have to instantly heat the water another 15+ degrees.
After a lengthy discussion with the other occupants of my house (my wife) about the definition of “hot water”, and some further discussion with my plumber, we arrived at an acceptable solution.
Passively pre-heat the water. And allow for an active pre-heater to be turned on.
Instead of running the water line from the street directly into the new tankless unit, we left it going to the old gas hot water tank and then from there into the tankless unit. And then turned the gas off. The tank serves as a reservoir at basement air temp (about 60 degrees) that slowly and passively raises to water temp from the street.
And if needed, we can always turn the tank on low to do some active pre-heating. The first winter we did that – set the tank on the lowest setting. But last winter we left it off. And so far this winter it has stayed off. But if we ever were in a situation where we are using more hot water in the coldest part of winter, we can always turn it back up.
One other note – per some YouTube videos – I flushed vinegar through the system last year to get any calcium buildup out of the heating elements. But the rinse came out pretty clean. I think that is more of a problem for well water systems. I’ll plan on doing that every other year.
Two gas burning appliances down (electric tankless water heater + electric heat pump home heater) and one to go (g
as range). That will take some careful negotiation. Maybe next year.