My earlier posts on residential sprinklers included a floor plan of a Home Run plumbing system and one showing how it can also serve sprinklers. The following drawing shows a floor plan with the complete system. Download Plumbing-based sprinklers
The key difference between Home Run plumbing and plumbing-based sprinklers is that the pipe from the manifold (shown here in red) now runs to sprinkler fittings instead of directly to plumbing fixtures. The pipe between sprinkler fittings is shown in black. The plumbing fixtures are served by the blue pipe. NFPA 13D allows one Tee fitting per pipe section to serve plumbing.
This is the same floor plan that I used to calculate the additional pipe needed to serve the sprinklers. The Home Run piping supplies 40 percent of the total needed to make it a plumbing-based sprinkler system. Note that garage has four sprinklers. If it were not heated and did not require the additional sprinkler pipe, the Home Run plumbing would have contributed around 50 percent of the sprinkler pipe.
Plumbing industry experts tell me that Home Run plumbing continues to gain market share. It costs less than traditional plastic and metallic systems, conserves water and energy, and provides a hydraulically balanced system. Combining them with manifolded sprinklers cuts the cost of sprinklers by around 50 percent. The water is 100 percent potable and thus eliminates backflow preventers. Advocates of residential sprinklers need to educate home builders and city officials about how they can protect lives at very reasonable costs.
An update: Since I first posted this, some PEX manufacturers have gotten their 3/4" pipe listed for fire protection systems. The manufacturer that I am most familiar with, Uponor USA, has replaced its manifolded system with a Simple Loop layout. I have asked them to provide a comparison between that and a traditional stand-alone system so that I can do a cost comparison.