Instantaneous Electric Water Heater

[alex7003]

Hi, I am wondering if any common requirements or best practice for a larger (e.g. 20-27 kW) instantaneous electric water heaters, similar to gas one? Does it require relief valve, check valve on supply and drain/service valves? Do they need water pressure tank? Installation manuals I could find address electrical wiring and refer to "local plumbing codes" for water connection.
Thanks!

 

[GReynolds929]

Generally they require the same plumbing that a gas tankless would need.

 

[chinarus]

Not a professional and no idea of code requirements but I have 3 installed in 2 residences without a water pressure tank.
Adequately sized wiring is the major concern - my opinion.
There are "service valves and flushing adapters" that make it easy to periodically drain or flush the unit.

Example:
https://www.amazon.com/s?k=flushing...4_10497738&tag=mh0b-20&ref=pd_sl_63webm0zwv_b

 

[psomerville]

I investigated installing one in a couple of different properties. It would have required installing some heavy gauge wire and upgrading the electrical panel. In addition, everything I read said the electric ones weren't that much more efficient than an electric tank heater.