Electric tankless water heaters

Ask this on the Home/Garden broad. You're likely to get better responses.

i would not do electric tankless, only Gas. to raise the temperate of one gallon of water 1 degrees F you need:

8.25 BTU/Gal*F

a 100,000 BTU gas heater with equally efficiencies need a 30 kW electric water heater.

for a 30 kW load you need a 240v 150 amp circuit

otherwise, lowering the kW will lower the capacity

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would not do electric tankless, only Gas.

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This

As a former plumber,dont do it. Tankless heaters are only viable in a gas setup. It's actually more cost effective to have a dedicated propane tank to solely fuel a tankless heater than to have an electric one. If you dont have access to NG and dont want to foot the bill for propane, get a standard electric heater (or 2) and recirculating pumps

Everything I've read says Electric Tankless is way to go. They are much cheaper, last longer, and are efficient. The only real benefit of gas is being able to heat up more Gallons Per Minute.

Gas vs Electric

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Gas tankless water heaters are designed to last 20 years.
Gas units are more difficult to service because they have a complex heat exchanger.
Warranties vary, but it's common to see a 10 year warranty for a heat exchanger, 5 years for other parts, and 1 year for labor.
Service life can be negatively impacted if the unit is not serviced on a regular basis.


Electric Tankless Water Heater
Electric tankless water heaters often exceed a 20 year lifespan because of the simplicity of their design.
Warranties vary, but parts are typically covered for 5 years and labor for 1 year.
When problems occur, an electric unit is easier to troubleshoot, diagnose and repair.

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You are going to have most tell you to avoid electric tankless, mainly those who have virtually zero experience with them and have absolutely zero experience installing them. I've installed gas and electric in residential and commercial settings and there are several cases where electric tankless is easily the better choice over gas. Especially in POU applications, gas tankless is almost idiotic there. It comes down to individual needs, expectations, and the practical realities around installation more than simple-minded gas over electric arguments you'll see posted here.

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Especially in POU applications, gas tankless is almost idiotic there.

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Absolutely a fact.

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It comes down to individual needs, expectations, and the practical realities around installation

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Absolutely true. The drawback to a retrofitted whole house tank-less system is the likelihood that your service will be undersized and require you to replace your feed to the house and at least modify your service entrance if not replace your main breaker panel.

If electric is your only option, odds are a standard, well insulated water heater is likely as good a choice as any.

The newer Hybrid or heat pump style water heaters with storage tanks are supposed to be somewhat more efficient but they are still new to me and I am unsure how well they will last. I would consider trying one of those if I had to use an electric.

Operating cost would favor propane tankless most likely.

Overall lowest cost would likely be a propane tank water heater.