12
Indoor Installation
Clearances
From top of water heater
12 inches
From back of unit
0.6 inch
From front of unit
6 inches (*) From left side of unit (gas piping side) 6 inches
From side wall flue or vent connector in any direction 6 inches
From right side of unit
2 inches
GU100 can be used as either Power-Vent or Direct-Vent appliance. When used as a Power-Vent appliance, the
water heater should be located in an area where enough air is available for proper combustion and ventilation.
Follow the latest edition of ANSI Z223.1 and any of your local codes that are applicable.
GU100 is a Category IV vented appliance and manufacturer's ventilation specifications should be followed.
In general these requirements specify that if the unit is installed in a confined space, there must be permanent air
supply openings if Eternal isn't installed as Direct-Vent.
When combustion air is supplied directly through an outside wall such as intake louver openings into the dwelling,
each opening should give a minimum free area of one square inch per 15,000 Btu/hour of the total input ratings of
all appliances in the enclosed area.
When combustion air is supplied from inside the building, each opening should give a minimum free area of one
square inch per 3,750 Btu/hour of the total input ratings of all appliances in the enclosed area. These openings
should never be less than 40 sq.in.
The minimum required inside air volume should be 50 cu.ft per every 3,750 Btu/hour.
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Combustion Air Supply
Air supply from outside building:
Air supply from inside building:
Minimum Recommended Air Supply To Water Heater as Power-Vent
Model #
Water Heater Capacity
Outside Air Area
Inside Air Area
GU100
Max. 100,000 Btu/hour
25 sq.in.
100 sq.in.
Model #
Water Heater Capacity
Minimum Required Air Volume
GU100
Max. 100,000 Btu/hour
1333 cu.ft
Air Vents
Heater
Air Vents
Heater
*For accessibility when performing maintenance, 24" clearance in front of the unit it is recommended.
Natural gas in high altitude might contain less heating value than typical 1100 BTU/ cuft and therefore can cause
improper air / gas mix leading to improper combustion. For natural gas installations in altitudes above 3,000 feet,
be sure to apply the intake orifice (P/N 152140230) provided by manufacturer in the accessory box.
WARNING - high elevation installations
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