Download EB home run (cold)Home-run plumbing is replacing traditional piping for three reasons. First, it costs less to install. The system uses more pipe than traditional trunk and branch piping, but the flexible 1/2-inch pipe eliminates the dozens of fittings needed for 3/4 or 1-inch rigid pipe on trunk and branch piping. The reduced labor and fitting costs more than offsets the cost of the additional pipe. The second reason is its hydraulic balance. Someone using a shower, for example, will not get a temperature or pressure shock when another plumbing fixture is opened.
The third reason is that home-run systems conserve water and energy. Studies conducted by the National Association of Home Builders show that home-run systems use 30-40 percent less water than traditional systems. The small diameter pipe is able to deliver tempered water faster, thus reducing the amount of water wasted while waiting for the desired temperature. That also results in less energy used to heat the water.
The attached illustration is a floor plan for a home-run plumbing system. The water service pipe enters through the garage and connects to a 1-inch copper manifold. The manifold has 1/2-inch ports that supply cold water to 14 plumbing fixtures and devices throughout the house. The three devices in the garage are the water heater and pumps for radiant floor heating. The fourth device treats water from the sinks and showers, and supplies the water to flush the toilets. That is why there are no cold water lines to the toilets.
When I look at the floor plan, I see more than a home-run plumbing system; I see one half of a sprinkler system. When sprinklers are added, the system becomes a manifolded grid that supplies the plumbing fixtures and sprinklers at the same time. My next post will include the same plan for the sprinkler portion and the complete combination of plumbing and sprinklers.
The floor plan is for a home being built in New Mexico, and the cost of the combined plumbing/sprinkler system is $1.50 per square foot. The cost breakdown shows that the sprinkler portion accounts for just under 60 percent of the total. This means that the sprinklers cost less than 90 cents per square foot. A similar system was recently installed in Minnesota where the total cost was 99 cents per square foot, so the sprinklers cost around 55 cents per square foot. How is that for affordable sprinklers?