Raindem

I'm replacing my electrical tankless HWH with a conventional tank HWH. Very dissapointed in the tankless performance but that's another story.

There are two electrical conduits going to the tankless, one for each of the coils I guess. How do I figure out which wires will be needed for my new heater? And for the ones that are not needed what do I do with them? Should I just install a box on the wall and cap them off?

Thanks

locknut

Do not understand what you're asking. Is the heater working properly on the line it's now connected to? Describe what the other wiring is and what used for.

JoeD

Tankless heaters take a bunch of power. Find the breakers that control those wires and verify the amperage is correct for your new heater. You may need to change the breaker if it is too high.
Cap one set of wires and use the other set to connect to your heater. Use a meter to determine which set is controlled by which breaker. Yes a box on the wall with a cover is required for the capped wires and to connect to your new heater.

Raindem

Joe, that points me in the right direction. There are 6 breakers on my fuse panel that are dedicated to the tankless unit, and only 2 conduits going to the unit. I'm guessing those are basically two 220V circuits. Do I just start flipping breakers and use a multi-meter to see which wires have power?

Thanks

JoeD

6 breakers tells me there are three 240 volt circuits to the heater. That is not uncommon.
The breakers should be double poles and likely 40 amps each. If they are not labeled then you will have to flip them to find the proper ones.