Annandale has some of Fairfax County's older housing, and a leaking or worn-out water heater in those homes is usually best replaced rather than patched. Fairfax County requires a permit for the swap, with a Household Appliance permit for a like-for-like gas unit and a Residential Plumbing permit if new gas piping goes in. Call the number on this page to be connected with a local plumber in Annandale.
Annandale homes and what they mean for a new heater
Annandale grew quickly after World War II, and its median home was built in 1968. Many houses still have original-era plumbing around the heater: older shutoff valves that may not close fully, aging flue connections into a chimney, and basements laid out long before today's bigger units. A replacement here often involves a little more than unhooking one tank and setting another.
Water comes from Fairfax Water, drawn from the Potomac and the Occoquan Reservoir. Testing at its Corbalis plant shows total hardness from about 70 to 185 mg/L, averaging around 7.5 grains per gallon, enough to leave sediment in a tank over time. Washington Gas serves most of the county. If you smell gas, leave the house first, then call 911 and Washington Gas at 844-WASHGAS (844-927-4427), option 1.
Repair or replace?
| Situation | Usually | Why |
|---|---|---|
| Tank leaking from the body | Replace | A corroded tank can't be patched |
| Pilot or burner trouble on a younger unit | Repair | Thermocouples and gas controls are replaceable parts |
| Rusty hot water, heater past ten years | Replace | The lining is likely failing |
| Not enough hot water after a family change | Replace with larger | The tank was sized for a different household |
| Relief valve dripping | Check first | Could be pressure, a bad valve or a missing expansion tank |
Signs to watch
- Damp concrete or rust flakes at the base of the tank
- Rumbling as the burner runs
- Hot water that fades faster than it used to
- Scorch marks or soot near the burner opening
Timing through the year
Older heaters often fail in the first cold snap, when colder supply water makes them run longer. Planning a replacement in late summer or fall gives time for the Fairfax County permit and avoids a rushed choice. In spring, Fairfax Water's switch to free chlorine can change how tap water tastes; that's the utility, not your heater.
If the basement is finished, think about the space around the heater before the new one goes in. A drain pan piped to a floor drain, a leak sensor and a clear path for the next replacement all cost little at install time and save trouble later. In homes where the chimney also served an old oil or gas furnace that has since been replaced, ask the plumber whether the flue still suits a new gas water heater on its own.
Water Heater Replacement questions in Annandale
Does replacing a water heater here need a permit?
Can the water heater go somewhere else in the house?
Can I change from gas to electric, or the other way around?
How do I look after the new water heater?
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