Sizing Guide

What you need to know when selecting an Electric Tankless Water Heater, CONTINUED
TYPICAL GPM REQUIREMENTS FOR VARIOUS FIXTURES:
SPECIAL MODEL OPTIONS:
PROPER SIZING EXAMPLE:
Let’s size an Eemax Electric Tankless Water Heater for
a bathroom in a new addition for a home. The goal is to
provide hot water for a full bathroom with one sink and a
standard shower. The application would be point-of-use
with only cold water lines running to the addition. The
first thing to know is the gallons per minute (GPM)
demand on the heater (all flow volumes are estimates,
fixtures GPMs may vary):
Bathroom Lavatory Sink = 0.5 GPM
Standard Shower = 2 to 2.5 GPM
Total GPM Demand = 3 GPM (running at
the same time)
The result of “Total GPM Demand” equals the number on
the left column of the Flow Chart Power Required guide
on the reverse side of this sheet. In this case, 3 GPM is
the result. If the result is a mixed number, we suggest
rounding up to the nearest whole number.
Next, it’s time to figure out how much heat is needed for
the lavatory sink and shower (typical desired showering
temperature is 110°F). Now, determine the average
incoming water temperature keeping the cold winter
months in mind. Subtract COLD WATER temperature
(Example 58°F) from the 110°F. The result equals 52°F
of TEMPERATURE RISE needed. For Flow Chart purposes,
it is recommended to round this number to 50°F.
Now, use the bottom row of numbers on the Flow Chart
Power Required guide and search for 50°F. Then read UP
from the bottom row to the intersection of 3 GPM from the
left column. Based on the above example and information
from the chart, the required kilowatt (kW) of power needed
is 22. This means, a 22kW Electric Tankless Water Heater
is needed for the application.
The next step would be selecting the proper Eemax heater
that best fits the application and one that provides enough
kW of at least 22. As an example for this specific applica-
tion, the Eemax SS023240TC would be best suited for
the single sink and a standard shower with an incoming
average water temperature of 58°F.
To find the proper water heater per the requirements,
please reference Eemax.com or refer to the Eemax
Quick Reference Product Spec Guide.
• RESIDENTIAL DISHWASHER = 1.0 – 2.0 GPM
• COMMERCIAL JANITORS SINK = 2.0 – 4.0 GPM
• SHOWER = 2.0 – 2.5 GPM (per shower head)
• WASHING MACHINE = 1.0 – 1.5 GPM
Average GPM figures based on 2010 plumbing standards.
• HAND WASHING SINK = 0.5 GPM
• CommerCial lavatory sink = 0.5 GPm
• residential kitChen sink = 2.0 GPm
• multi-ComPartment wash sink = 2.5 – 3.0 GPm
EE = Emergency Eyewash – Meets ANSI tepid water requirements.
ML = Multi-Lav – Factory preset to 110°F with 0.3 GPM turn-on.
S = Sanitation – Factory preset not to exceed 180°F.
FS = Factory Set – Customer specified factory-set not to exceed temperature ambient to 180°F.
SL = Single Lav – 3/8” compression fittings standard. Available on EX non-thermostatic models only.
DL = Dual Lav. – (2) 0.5 GPM aerators supplied as standard.
T3 = Thermostatic (parallel turn on) Activates 1.8 GPM, Max Flow 5 GPM.
T4 = Thermostatic (parallel turn on) Activates 2.6 GPM, Max Flow 8 GPM.
T2T = Thermostatic (staged turn on) Activates 0.7 GPM, Max Flow 4 GPM.
T2T2 = Thermostatic (staged turn on) Activates 0.9 GPM, Max Flow 6 GPM.
NEMA 4 = Optional Waterproof Cabinet – Hinged cover. Powder coated finish.
NEMA 4x = Optional Waterproof Corrosion-Resistant Cabinet – Stainless steel.