Installing a fire sprinkler system itself is not a requirement of all homes, but it is available as an option to homeowners for additional safety in the event of a fire. The International Residential Code dictates the placement of sprinklers in relation to many parts of the room, even the air supply registers. The minimum distance from an air register to the sprinkler depends on the type of heating, ventilation and air conditioning system you have and the location of the register.
Sprinklers placed near air supply registers must have a higher temperature rating than typical sprinklers. This will keep the sprinkler from being accidentally set off by a blast of heat from a heater duct. Regular sprinklers set off at temperatures between 135 and 175 degrees Fahrenheit. Intermediate temperature sprinklers for use near air registers rate between 175 and 225 degrees Fahrenheit.
Type of Register
The code only makes a requirement for a sprinkler to be located in proximity to a heated-air supply register. If you do not have a central heating system and only use air conditioning, there is no minimum distance you must place the sprinkler. Even if you use the registers only for cool air in the summer, you must follow the code's guidelines for sprinkler distances if heated air can come out of the register.
Wall-Mounted Air Supply Registers
The location of the sprinkler in relation to a wall-mounted air register will indicate the minimum distance. According to the "The 2012 International Residential Code for One and Two Family Dwellings" by the International Code Council, if the sprinkler is directly in front of a wall-mounted register, the sprinkler must be between 18 and 36 inches away. Some sprinklers are mounted on the wall and cannot be in front of the register. In this instance, the sprinkler needs to be between 12 and 24 inches from the register.
Registers on the Ceiling
Registers that expel heated air from the ceiling have similar requirements for placing the sprinkler as wall-mounted registers. If you install the sprinkler on the ceiling or wall, it must be between 12 and 24 inches, according to table P2904.2.2 of the 2011 IRC.