Three phase water heater with simultaneous heating elements

[Hv&Lv]

Wouldn't a three-phase water heater have three heating elements?

Depends on size....
some have 9 elements, a single U
some have three elements which have a 3U element

 

[Greg1707]

Don't know what is common, but wouldn't necessarily have to. For balanced loading it kind of needs to have some multiple of three of equal rating, but could also have just two elements connected in open delta fashion.

According to the instruction manual regardless of how the unit is connected it will operate in an unbalanced fashion.

Element connection is for non-simultaneous operation. This means only one element at a
time operates. The wiring diagram, on page 12, shows the heater may be field converted to simultaneous element operation by moving the
red wire on L1. It is then possible for both elements to operate at once as determined by the thermostats.
Regardless of element connection the heater operates in an
"unbalanced"fashion.

 

[LarryFine]

Wouldn't a three-phase water heater have three heating elements?

I didn't express it above, but that's what I was thinking, too.

 

[LarryFine]

According to the instruction manual regardless of how the unit is connected it will operate in an unbalanced fashion.

Element connection is for non-simultaneous operation. This means only one element at a
time operates. The wiring diagram, on page 12, shows the heater may be field converted to simultaneous element operation by moving the
red wire on L1. It is then possible for both elements to operate at once as determined by the thermostats.
Regardless of element connection the heater operates in an
"unbalanced"fashion.


View attachment 2551420

So, this is another open-delta discussion.

 

[kwired]

So, this is another open-delta discussion.

Looks to me like connected in open delta, or can be connected to single phase supply. If non simultaneous operation of elements there is no point in supplying it with three conductors and spending the extra $$ on a three pole breaker and/or three pole disconnect either.