How to reduce your “hot-water rectangle”
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We’ve previously covered the concept of the “hot-water rectangle” — draw a rectangle around the water heater and all the hot-water fixtures in a house, then divide the conditioned floor area of the home by the area of the rectangle. Hot-water expert Gary Klein, who developed the concept, has pushed builders and architects to reduce the ratio represented by that hot-water rectangle to make plumbing systems more efficient and get hot water to the fixtures faster.
In his Energy Vanguard blog, Allison Bailes covers a new report from the California Energy Commission written by Klein and collaborators, Code Changes and Implications of Residential Low Flow Hot Water Fixtures (CEC-500-2021-043). Builders, Bailes says, have a variety of options to reduce the size of the hot-water rectangle, from moving fixtures in an existing floor plan to modifying floor plans so that fixtures and water heaters are close together. Remodelers, however, face more challenges with existing homes.
“One option is to replace the hot water pipes (assuming they’re accessible),” Bailes writes. “Without changing the floor plan, you may be able to reduce the length and also right-sizing the diameters. Another option is to move the water heater to a more central location, if that’s possible. Then reroute and right-size the piping at the same time. Or you could replace one large water heater with two or more smaller ones, closer to the hot water fixtures.”
With their small footprint, propane tankless water heaters are an ideal option for remodelers looking to install multiple appliances closer to the fixtures. Check out our Ultimate Guide to Tankless Water Heaters for installation tips that make it easier to run ventilation and gas lines to locations throughout the home.