Providing hot water quickly at the tap can be maddeningly difficult for a builder or plumber to achieve. And the problem is getting worse, Gary Klein writes in The Journal of Light Construction.
“On the one hand, houses keep getting bigger,” he writes. “That means that bathrooms and kitchens are spread out over a larger and larger area. Moving hot water from the water heater to the bath or kitchen fixtures requires longer and longer runs of pipe.
“At the same time, flows at fixtures have continued to be constrained by federal and state water-conservation standards. In 1980, a residential bathroom lavatory faucet had a flow rate of 3.5 gallons per minute (gpm) or more. Under current plumbing codes, that fixture can draw only 2.2 gpm. And under some stricter state codes, those faucets can draw only 1.2 gpm — a reduction of 66% since 1980.”
In today’s homes, dumping those long runs of standing water can take two minutes before the hot water comes, wasting water, energy, and time. But what happens if you cluster “wet rooms” like the kitchen, laundry, and bath so they’re closer to the water heater? Klein looks at a Habitat for Humanity success story where the builder shrank the hot-water system rectangle to 0.8 percent of the home’s floor area, using a tankless water heater to deliver hot water to the kitchen in 12 seconds.