Page 659 - 2018_IRC

WATER SUPPLY AND DISTRIBUTION

TABLE P2902.3.1
MINIMUM AIR GAPS
MINIMUM AIR GAP
FIXTURE Away from a wall a Close to a wall
(inches) (inches)
Two times the diameter of the Three times the diameter of the
Effective openings greater than 1 inch
effective opening effective opening
Lavatories and other fixtures with effective opening not 1 1 . 5
1
greater than / inch in diameter
2
Over-rim bath fillers and other fixtures with effective 2 3
openings not greater than 1 inch in diameter
Sink, laundry trays, gooseneck back faucets and other
3
fixtures with effective openings not greater than / inch 1.5 2.5
4
in diameter
For SI: 1 inch = 25.4 mm.
a. Applicable where walls or obstructions are spaced from the nearest inside edge of the spout opening a distance greater than three times the diameter of the
effective opening for a single wall, or a distance greater than four times the diameter of the effective opening for two intersecting walls.
P2902.5 Protection of potable water connections. Connec- P2902.5.4.1 Additives or nonpotable source. Where
tions to the potable water shall conform to Sections systems contain chemical additives or antifreeze, or
P2902.5.1 through P2902.5.5. where systems are connected to a nonpotable secondary
P2902.5.1 Connections to boilers. Where chemicals will water supply, the potable water supply shall be pro-
not be introduced into a boiler, the potable water supply to tected against backflow by a reduced pressure principle
the boiler shall be protected from the boiler by a backflow backflow prevention assembly or a reduced pressure
preventer with an intermediate atmospheric vent comply- principle fire protection backflow prevention assembly.
ing with ASSE 1012 or CSA B64.3. Where chemicals will Where chemical additives or antifreeze is added to only
be introduced into a boiler, the potable water supply to the a portion of an automatic fire sprinkler or standpipe
boiler shall be protected from the boiler by an air gap or a system, the reduced pressure principle fire protection
reduced pressure principle backflow prevention assembly backflow preventer shall be permitted to be located so
complying with ASSE 1013, CSA B64.4 or AWWA as to isolate that portion of the system.
C511. P2902.5.5 Solar thermal systems. Where a solar thermal
P2902.5.2 Heat exchangers. Heat exchangers using an system heats potable water to supply a potable hot water
essentially toxic transfer fluid shall be separated from the distribution or any other type of heating system, the solar
potable water by double-wall construction. An air gap open thermal system shall be in accordance with Section
to the atmosphere shall be provided between the two walls. P2902.5.5.1, P2902.5.5.2 or P2902.5.5.3 as applicable.
Single-wall construction heat exchangers shall be used only P2902.5.5.1 Indirect systems. Water supplies of any
where an essentially nontoxic transfer fluid is utilized. type shall not be connected to the solar heating loop of
an indirect solar thermal hot water heating system. This
P2902.5.3 Lawn irrigation systems. The potable water
supply to lawn irrigation systems shall be protected against requirement shall not prohibit the presence of inlets or
backflow by an atmospheric vacuum breaker, a pressure outlets on the solar heating loop for the purposes of ser-
vacuum-breaker assembly or a reduced pressure principle vicing the fluid in the solar heating loop.
backflow prevention assembly. Valves shall not be installed P2902.5.5.2 Direct systems for potable water distri-
downstream from an atmospheric vacuum breaker. Where bution systems. Where a solar thermal system directly
chemicals are introduced into the system, the potable water heats potable water for a potable water distribution sys-
supply shall be protected against backflow by a reduced tem, the pipe, fittings, valves and other components
pressure principle backflow prevention assembly. that are in contact with the potable water in the system
P2902.5.4 Connections to automatic fire sprinkler sys- shall comply with the requirements of Chapter 29.
tems. The potable water supply to automatic fire sprinkler P2902.5.5.3 Direct systems for other than potable
systems shall be protected against backflow by a double- water distribution systems. Where a solar thermal
check backflow prevention assembly, a double-check fire system directly heats water for a system other than a
protection backflow prevention assembly, a reduced pres- potable water distribution system, a potable water sup-
sure principle backflow prevention assembly or a reduced ply connected to such system shall be protected by a
pressure principle fire protection backflow prevention backflow preventer with an intermediate atmospheric
assembly. vent complying with ASSE 1012. Where a solar ther-
Exception: Where sprinkler systems are installed in mal system directly heats chemically treated water for a
accordance with Section P2904.1, backflow protection system other than a potable water distribution system, a
for the water supply system shall not be required. potable water supply connected to such system shall be
protected by a reduced pressure principle backflow pre-
vention assembly complying with ASSE 1013.

634 2018 INTERNATIONAL RESIDENTIAL CODE ®
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