Electrician's White Paper - Heatworks 1 Manual

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ELECTRICIAN'S WHITE PAPER

ELECTRICAL SERVICE:
The Heatworks MODEL 1 tankless water heater is
considered a non-continuous heating appliance
according to the Definitions in the National Electric Code.
An appliance load that is not continuous for 3 hours or
more is considered non-continuous. Therefore, the
MODEL 1 heater, when used for standard domestic hot
water applications, is considered a non-continuous
heating appliance. Due to the diversity of water heating
in a home, the load (amps) contribution of the MODEL 1
heater to the overall service load of the home or building
can be calculated using the optional methods of National
Electrical Code, sections NEC 220-82 or 220-83.
For new dwellings, the service load should be calculated
using NEC 220-82. For existing dwellings, the service load
should be calculated using NEC 220-83. By both
calculation methods, the Heatworks MODEL 1 load is
generally added to the service load at 40% of it's
maximum nameplate rating. For instance, the maximum
current (amp) rating of the Heatworks MODEL 1 is 48
amps and 40% of this rating is about 20 amps. The 20
amps is typically the load added to the overall service
load of the dwelling when using the optional calculation
methods as described in NEC 220-82 and 220-83, not the
maximum current rating, 48 amps. (Note that a
conventional electric water heater rated at 30 amps load
will be rated at 30 amps as is it considered a continuous
device.)
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So, two Heatworks MODEL 1s will actually add 20 amps
more to the existing service load. As a result, one or
more Heatworks MODEL 1s will fit in most homes that
have a 150 or 200 amp whole-house electrical service, or
can be installed using one or more sub-panels with a
breaker that is sized accordingly.
POWER/VOLTAGE MODULATION:
During operation, the Heatworks MODEL 1 is designed to
use only the power necessary to heat the water for
various combinations of temperature rise and flow rate.
DISCONNECTS AND SUB-PANELS:
Electrical disconnect devices do not contain circuit
breakers and are not required by the National Electrical
Code (NEC) for residential appliances such as the
Heatworks MODEL 1 water heater or any appliance rated
less than 300 volts. However, disconnects may be
required by the NEC for motor loads and for appliances
with multiple circuits in commercial applications.
CAUTION: Breaker must remain off until installation is complete.
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