Tankless Water Heater in Centreville, VA

Signs worth acting on

• The original builder's tank is still in the basement or garage and approaching the end of its service life
• Hot water runs short when guests stay or teenagers shower back to back
• Faucet aerators and showerheads collect white scale
• An existing tankless heater beeps, shows a code or shuts down when two fixtures run
• The water heater closet is crowded and you want floor space back

What Centreville homes start with

Centreville is unincorporated Fairfax County, and the median home here was built in 1991, so most houses have copper or PEX supply lines and a gas tank in a basement utility room. That makes the plumbing side of a conversion fairly simple. The gas side is where the work is: a tank of that era was usually piped with just enough capacity for itself and a furnace, and a tankless burner at full fire needs more.

Fairfax Water supplies Centreville from the Potomac River and the Occoquan Reservoir. Its finished-water tests from the Potomac plant show total hardness of roughly 70 to 185 mg/L, averaging about 128 mg/L or 7.5 grains per gallon, with the Occoquan plant's results in a similar range. That level calls for isolation valves and a regular descaling flush. Fairfax Water switches from chloramines to free chlorine from about April to June, which can change taste for a few weeks but does not affect the heater.

What changes the cost

• Permit type. Fairfax County uses a Household Appliance (HAPL) permit for like-for-like gas heater swaps with no new gas piping, and a Residential Plumbing permit once new gas pipe is added, as it often is for tankless.
• Gas pipe. Length and size of the new run from the meter.
• Vent path. Sidewall venting from a basement rim joist is usually simplest.
• Unit size. Flow rating needed for your fixtures in winter.
• Scale control. Optional cartridge or softener ahead of the unit.

What happens when you call

You are connected with an independent plumber who works in Centreville. Share the age of your current heater, how many bathrooms you have and where the gas meter sits relative to the utility room. Permits go through the County's PLUS system, and the plumber usually handles that. Gas here is Washington Gas: if you ever smell gas, leave the house, then call 911 and 844-WASHGAS (844-927-4427), option 1, from outside.