Tankless Water Heater in Washington, DC

Why people switch

• A wall-hung unit frees up space in a small basement or utility closet
• Hot water keeps coming as long as the unit can keep up with demand
• No large tank keeping a store of water hot while nobody is using it

What a tankless install involves

Gas tankless units draw far more fuel at full fire than a typical tank heater, so the gas line from the meter often has to be upsized. Most models need their own vent, either through an outside wall or the roof, which can be tricky in attached rowhouses with limited exterior walls. Electric whole-house models need substantial electrical capacity that many older DC panels do not have. A plumber should check all three before quoting.

Permits

The DC Department of Buildings issues the Plumbing and Gas Permits for this work, and gas appliance installations fall under that process. Trade permits can only be pulled by a contractor holding a DC license for that trade, so confirm the permit is included in the price.

Scale and DC water

DC Water reports moderately hard water, typically about 70 to 120 ppm (3 to 9 grains per gallon), and its annual water quality report lists an average total hardness near 126 ppm. Tankless heat exchangers have narrow passages, so even moderate minerals can build up over time and set off error codes or reduce flow. Most manufacturers call for periodic flushing with a descaling solution through isolation valves. Homes with a water softener may need it less often.

Common service calls

Is it right for your home?

Tankless makes the most sense when space is tight and the gas line and vent route are workable. In some older homes the cost of gas and venting upgrades tips the balance back toward a high-efficiency tank or a heat pump unit. Ask the plumber to price both options.

Cost factors

• Gas line upsizing and new venting
• Electrical work for electric models
• Unit capacity and whether it is condensing
• Permit and inspection