Selma's main water system runs on town wells and more than half its homes predate 1980, so a tankless water heater here calls for a descaling plan and often new venting and gas work. Permits go through Johnston County after Town zoning approval. Call the number on this page to be connected with a local plumber in Selma.
Selma at a glance
Selma's main water system draws on the town's own groundwater wells and disinfects with chlorine rather than chloramine, per the 2025 report; a separate Selma-Countyline system distributes surface water bought from Johnston County. Neither report lists hardness, but groundwater often carries more minerals than surface water. The housing is older: the median home was built in 1974 and about 55% predate 1980, per Census survey data. Johnston County is in Piedmont Natural Gas territory, with availability depending on the street.
What to do now
- Know your water system. Check your bill or ask the Town whether you're on the main system or Countyline.
- Check the fuel. Gas meter, propane tank or all-electric?
- Look at the heater's spot. Closet, utility room or porch, and how far it is from an outside wall.
- Record any codes on an existing tankless unit.
- Find the panel and note its amp rating if you're considering electric.
- If you smell gas, leave and call 911 or Piedmont at 800-752-7504 from outside.
Signs and likely causes
| Symptom | Likely cause |
|---|---|
| Hot flow slowly weakening | Mineral scale in the heat exchanger |
| Grit in hot-side aerators | Sediment passing the inlet screen |
| Burner lights, then shuts off | Flame sensor, gas pressure or venting |
| Temperature swings with two fixtures open | Unit at its flow limit |
| Rumbling old tank heater | Sediment buildup; replacement may be near |
What changes the cost
- Upsizing a gas line sized for a tank and furnace
- A new dedicated vent, and capping any shared flue
- Panel capacity for electric models
- A softener or filter ahead of the unit on well water
- Permits: Selma's permits page lists Town zoning approval first, then Johnston County Building Inspections in Smithfield
In many older Selma houses, the vent and gas line together cost more than the heater. Where the water heater sits in an interior closet, moving it to an exterior wall can shorten the vent but lengthen the water lines, and the plumber can lay out both options. If you're on well water, adding a softener or filter at the same visit usually costs less than coming back for it later, and it protects the heat exchanger from the start.
Tankless Water Heaters questions in Selma
How often should a tankless heater be descaled?
Is well water hard on a tankless heater?
Will my gas piping need to be upsized for a tankless heater?
How long does a tankless water heater last?
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