Hi, I have some confusion about wiring tankless electric water heaters.

#1 When does one require a sub panel, and if so why?

#2 Is there a distinction made between tankless heaters for space
heating and tankless heaters for potable water? There's a tankless
company out there with a separate model for each situation. The
potable model is not UL listed, should I worry about that?

I have the 2002 NEC. If you could site chapter and verse it would be
appreciated.

how many amps does your perspective heater need? most need a 200 amp
main panel just for heating water, so your looking at a major service
upgrade probably 200 amp for regular home uses and 200 amps fopr
heating water. with new service drop and power company may need to
upgrade neighborhood.

how do you heat water currently?

There is a difference between models for heating water and domestic water,
there are also a number of sizes and wattages. You need to determine what
you're going to use it for, and how much water you need it to produce, then
you need an electric service of adequate size. Some domestic units run at
28KW, or 116 amps @240 volt, which would require your house service to be a
minimum of 200 amps




wrote in message
ups.com...
Hi, I have some confusion about wiring tankless electric water heaters.

#1 When does one require a sub panel, and if so why?

#2 Is there a distinction made between tankless heaters for space
heating and tankless heaters for potable water? There's a tankless
company out there with a separate model for each situation. The
potable model is not UL listed, should I worry about that?

I have the 2002 NEC. If you could site chapter and verse it would be
appreciated.

RBM remove this wrote:
There is a difference between models for heating water and domestic water,
there are also a number of sizes and wattages. You need to determine what
you're going to use it for, and how much water you need it to produce, then
you need an electric service of adequate size. Some domestic units run at
28KW, or 116 amps @240 volt, which would require your house service to be a
minimum of 200 amps



Actually you would need TWO mains one just for heating water!

116 amps or water leaves little to run the entire remainder of home
which is today generally 200 amps. you dont want to be at 200 amps all
the time.

you will need a pair of 200 amp main services one just for heating water

Actually, a professional would do a load calculation and determine exactly
what size service is needed, but as I stated, and I'm also quoting the
manufacturer, 200 amp would be a minimum




wrote in message
ups.com...

RBM remove this wrote:
There is a difference between models for heating water and domestic
water,
there are also a number of sizes and wattages. You need to determine what
you're going to use it for, and how much water you need it to produce,
then
you need an electric service of adequate size. Some domestic units run at
28KW, or 116 amps @240 volt, which would require your house service to be
a
minimum of 200 amps



Actually you would need TWO mains one just for heating water!

116 amps or water leaves little to run the entire remainder of home
which is today generally 200 amps. you dont want to be at 200 amps all
the time.

you will need a pair of 200 amp main services one just for heating water

84 amps isnt enough to run a normal home today, and actually you would
have what 80% of that?

2 mains will be a minimum

the tankless sellers dont like talking about this...... whats a typical
cost a few grand?

As a licensed electrical contractor, we don't use terms like "normal home"
we do load calculations



wrote in message
ups.com...
84 amps isnt enough to run a normal home today, and actually you would
have what 80% of that?

2 mains will be a minimum

the tankless sellers dont like talking about this...... whats a typical
cost a few grand?

RBM (remove this) wrote:
As a licensed electrical contractor, we don't use terms like "normal home"
we do load calculations



wrote in message
ups.com...
84 amps isnt enough to run a normal home today, and actually you would
have what 80% of that?

2 mains will be a minimum

the tankless sellers dont like talking about this...... whats a typical
cost a few grand?


so licensed electrical contractor what kinda home could run on so few
amps remaing after the taness is in use?

moreover the bare minimum today is 100 amp, this home wouldnt have a
100 amps available for all other uses........

no way would this pass inspection