Opponents of home fire sprinkler systems often cite extremely high costs associated with integrating NFPA 13D home fire sprinklers into a well water supply system. The following will explain how this is accomplished in an efficient and cost-effective manner.
Well systems incorporating fire sprinklers at the start of the building process are set up to address this fire protection application. Water sits in three areas in a well-fed system: in the well above the pump, refilling into the well as it is used, and in the holding tank in the home. Per NFPA 13D the refill rate can be counted on to help supply part of the demand, thus, the duration demand of 7 or 10 minutes can be met by the sum of these three sources.
A larger well pump is usually installed along with larger expansion tanks. Homes on well water most likely will need a pump to serve the domestic water supply. The cost associated with providing additional pressure to run the fire sprinkler system may simply be the difference between the regular pump the homeowner must install to obtain the necessary pressure for domestic use, and a higher flow pump, or a booster pump and tank. The expansion tanks are sized to pick up the difference between the well capacity and demand thus they are not necessarily as large as some would believe.
Stand alone tank systems are similar to the pressurized tank systems in that they can be set up to provide for the difference in supply as opposed to total demand. In this case, a separate pump is required. It has the benefit of not being used for anything but the fire demand, so the system is never
Stand-by power is not required by code, but many manufacturers build their systems with battery back-up as a standard feature.
According to one of the manufacturers consulted on this technical issue, they “sell systems every day to meet the varying demands of the marketplace. Every situation is not the same but we have yet to find a scenario which cannot be addressed technically or cost effectively.”
Read the Integration of Residential Sprinklers with Water Supply Systems report for additional information.