Tankless Water Heater in Rockville, MD

Who issues the permit for a tankless heater in Rockville?

The City of Rockville water system serves about 70% of the city, and WSSC Water serves the remainder. The City's Express Water Heater Permit Guide says addresses on City water apply to the Department of Community Planning and Development Services (CPDS) online through MGO Connect, while WSSC-water addresses get the permit from WSSC Water Permit Services. The City publishes a Water Service Provider Map, and your water bill also shows the provider. A plumber working in Rockville will know the drill, but it helps to know which side of the line you're on.

Will my Rockville house need gas and vent work?

Probably some. Rockville's median home was built around 1980, mixing postwar subdivisions such as parts of Twinbrook with later development. Tank heaters in those houses usually share a flue with the furnace and run on a gas line sized for modest loads. A whole-house tankless burner needs a larger supply and its own sealed vent, typically through a basement or garage wall. If the furnace stays in the old chimney alone, the plumber checks that it still drafts correctly. Gas units also need an outlet for their controls.

What about the water itself?

City of Rockville water comes from the Potomac River and is disinfected with chlorine; WSSC-served addresses get WSSC's treated water. Hardness varies by provider and plant, and each utility's annual water quality report is the place to look. Either way, plan on isolation valves and a yearly flush to keep scale out of the heat exchanger. Units with good access to those valves cost less to maintain over time. Mounting the heater where a hose and bucket fit easily, rather than tucked behind a finished wall, makes that yearly chore a quick job instead of a project.

A Rockville note

Winter is when an undersized tankless unit shows itself, because incoming water is colder and flow at a set temperature drops. Ask the plumber to size for January, not for the day of the install. And if you ever smell gas near the heater, leave the house first, then call 911 and Washington Gas at 844-WASHGAS (927-4427), option 1, from outside. If your bill comes from a different gas utility, use that company's emergency line instead.