Tankless Water Heater in Greenville, SC: Worth It, Costs and Sizing

By the GVL Plumbers editorial team · Updated Oct 30, 2026 · 6 min read

Tank vs tankless vs heat pump

Do you have gas?

Gas tankless makes the most sense when natural gas is already at the house. Piedmont Natural Gas serves most of Greenville County; in much of Greer, Greer CPW supplies gas. If your home has no gas service, adding it is a separate, larger project that usually rules tankless out on cost.

Even with gas, a tankless unit draws far more gas at full fire than a tank burner does. The plumber has to check that the meter and the gas line can supply it, and may need to run a larger line. Ask about this on the quote; it's the most common reason prices differ between companies.

Rebates: Piedmont Natural Gas has listed a rebate for qualifying high-efficiency gas tankless water heaters in South Carolina (shown at $250 for a unit rated 0.81 UEF or higher), but its pages differ on residential eligibility and the deadline. Confirm with Piedmont at (800) 951-9923 before you buy.

Greenville's soft water is good news for tankless

Scale is the main enemy of tankless heaters: minerals coat the heat exchanger, cut efficiency and trigger error codes. Greenville Water is soft, about 5–7 mg/L of hardness in its 2026 reports, so scale builds slowly here. Manufacturers still call for periodic flushing with a descaling solution, and skipping it can affect the warranty. Ask how often your model needs it; on soft water it's usually at the long end of the range. Greer CPW and well customers should check their own water's hardness.

Sizing: flow rate, not gallons

A tankless unit is sized by how many gallons per minute it can heat, and by how much it has to raise the temperature. Upstate groundwater and reservoir water run colder in January than in July, so a unit has to work hardest in winter.

• A shower uses about 2 gallons a minute; a kitchen faucet about 1.5; a dishwasher or washer about 1–2.
• Add up what runs at the same time on a winter morning. Two showers plus a faucet is about 5–6 GPM.
• Gas units around 8–11 GPM cover most 2–3 bathroom homes. A unit sized only for summer will run lukewarm in a January cold snap.

Example: a family with two bathrooms that runs two showers at once in winter needs a unit rated for about 5–6 GPM at a 70°F temperature rise, not just its summer rating.

What the install involves

1. Remove the old tank and haul it away.
2. Mount the unit on a wall, inside or outside depending on the model.
3. Run new venting. Tankless units usually can't use the old tank's flue. Condensing models vent through PVC and need a condensate drain.
4. Upsize the gas line if needed, and add isolation valves for flushing.
5. Get the permit and inspection. Mauldin requires a permit for any water heater replacement, and Greenville County lists water heaters on its residential plumbing permit forms. Ask whether the permit is in the price.

Tax credits and timing

The federal 25C credit, which covered qualifying high-efficiency water heaters, ended for equipment placed in service after December 31, 2025. A 2026 quote that subtracts a federal credit is out of date. Utility rebates, where they apply, are separate.

Downsides to know before you switch

• A short wait for hot water at the tap, and occasional "cold sandwich" bursts when a tap is turned off and on quickly.
• No hot water in a power outage, gas units included, since they need electricity to run. After Helene left about 275,000 Greenville County outages in 2024, that's worth weighing.
• Yearly maintenance to keep the warranty valid.
• Higher upfront cost that takes years of gas savings to pay back.

Tankless repair

Tankless repairs run about $146–$864 in Greenville, averaging about $556 (HomeAdvisor). Common causes are scale or sediment, a failed igniter or flame sensor, venting or condensate faults, and inadequate gas supply. Note the error code on the display before you call; it saves diagnosis time. Our water heater repair guide covers tank problems.

Tankless water heater questions