Tankless water heaters — sometimes called on-demand or instantaneous water heaters — have become the default upgrade for homeowners replacing an aging tank unit, mainly because they heat water only as it’s used instead of keeping 40-plus gallons hot around the clock. But once you’ve decided to go tankless, the electric-vs-gas question has real consequences for your upfront cost, your monthly utility bill, and whether the unit can actually keep up with your household.
Gas tankless water heaters deliver higher flow rates (typically 8–10 GPM) and handle whole-house demand more easily, but cost more upfront and need proper venting. Electric tankless units are cheaper to install and slightly more energy-efficient per unit of energy used, but are usually limited to 2–5 GPM unless you upgrade your electrical panel significantly. In much of Fehl Safe’s inland service area, where natural gas lines aren’t available, “gas” tankless means propane — which changes the cost math and is worth factoring in before you decide.
Tankless water heaters — sometimes called on-demand or instantaneous water heaters — have become the default upgrade for homeowners replacing an aging tank unit, mainly because they heat water only as it’s used instead of keeping 40-plus gallons hot around the clock. But once you’ve decided to go tankless, the electric-vs-gas question has real consequences for your upfront cost, your monthly utility bill, and whether the unit can actually keep up with your household. Here’s how they actually compare.
How They Work, in Short
Both electric and gas tankless units skip the storage tank entirely, heating water as it flows through the unit on demand. The difference is the heat source: electric models use resistance heating elements, while gas models (natural gas or propane) use a gas burner. That single difference drives almost every other point of comparison below.
Upfront Cost and Installation
Electric tankless units are generally cheaper to buy, and for a home that already has adequate electrical service, installation can be relatively straightforward. The catch is “adequate electrical service” — a whole-house electric tankless unit can require a dedicated 150-plus amp circuit, which often means an electrical panel upgrade on older homes, adding real cost back into the project.
Gas tankless units cost more upfront and require proper venting — typically a dedicated stainless steel or PVC vent run to the exterior, sized and installed to manufacturer spec. If a home doesn’t already have gas service, running a new gas line (or setting up a propane tank and delivery service) adds to the installation cost as well.
Florida-specific consideration: A lot of inland and rural parts of Fehl Safe’s service area — Myakka City, DeSoto County, Hardee County — don’t have municipal natural gas lines. “Gas” tankless in those areas almost always means propane, which involves either a buried or above-ground propane tank and a delivery contract. That’s a different cost and logistics picture than a gas tankless installation in a neighborhood with existing natural gas service, and it’s worth factoring in before comparing sticker prices.
Flow Rate and Whole-House Capacity
This is usually the deciding factor for larger households. Gas tankless units typically deliver 8–10 gallons per minute, enough to run multiple showers and appliances simultaneously without a drop in water temperature. Electric tankless units are generally limited to 2–5 GPM for a single unit, which is often fine for a smaller home or a single point-of-use application (like one bathroom), but can require multiple units, or isn’t realistic at all, for whole-house demand in a larger household without a major electrical upgrade.
Efficiency and Operating Cost
Electric tankless units have an edge in raw energy efficiency, with Uniform Energy Factor (UEF) ratings commonly in the 0.93–0.99 range, since essentially all the electrical energy going into the unit converts to heat. Gas units typically run a UEF of 0.80–0.95, losing some energy through combustion and venting.
That efficiency advantage doesn’t automatically mean electric is cheaper to run, though — actual operating cost comes down to local utility rates. Where electricity is relatively expensive relative to natural gas, a gas unit can still cost less to operate month to month despite the lower efficiency rating. Where propane is the “gas” option, delivery costs and current propane pricing need to be part of that comparison — propane is typically more expensive per unit of energy than natural gas.
Maintenance
Both types need regular maintenance to perform well and last — especially in areas with hard well water, where mineral scale buildup is one of the most common causes of reduced flow and premature failure in tankless units of either kind. Gas units have additional components (burner assembly, venting, gas valve) that need periodic inspection. Electric units have fewer moving parts but still need periodic descaling, especially on well water systems without prior water treatment.
Lifespan
Both electric and gas tankless water heaters commonly last 15–20 years with proper maintenance — meaningfully longer than a typical 8–12 year lifespan for a tank-style water heater — provided scale buildup and component wear are addressed on schedule rather than ignored.
Which One Should You Choose?
As a general rule: if your home already has natural gas service and your household needs high simultaneous hot water demand, a gas tankless unit is usually the better fit. If your electrical panel already has the capacity for a large dedicated circuit and your hot water demand is moderate, electric tankless can be the simpler and cheaper installation. If you’re in one of the inland parts of our service area without natural gas access, the real comparison is electric vs. propane, not electric vs. gas in the abstract — and that changes the math enough that it’s worth having an actual load and demand assessment done for your specific home rather than assuming either option automatically wins.
Common Questions
Do tankless water heaters work with well water? Yes, but well water — particularly hard water with high mineral content, common throughout our inland service area — accelerates scale buildup inside a tankless unit’s heat exchanger. A water softener or filtration system upstream of the unit significantly extends its service life and keeps flow rates from degrading.
Is electric or gas tankless water heater better? Neither is universally better — it depends on your existing electrical or gas service, your household’s hot water demand, and local utility costs. Gas units handle higher simultaneous demand; electric units are typically cheaper to install where adequate electrical capacity already exists.
How much does it cost to install a tankless water heater in Florida? Installation cost depends heavily on whether existing electrical or gas/propane infrastructure needs upgrading. A straightforward swap into existing service is far less expensive than a job requiring a panel upgrade, new gas line, or propane tank setup — which is why an on-site assessment matters more than a generic price estimate.
Because Fehl Safe handles plumbing, well and water treatment systems, and water filtration all under one roof, we can evaluate a tankless installation alongside your home’s actual water quality — not just the unit itself. If well water hardness is going to shorten a tankless heater’s life before it’s even installed, that’s something worth knowing up front, not after the first service call.
Call us today at (941) 202-4428 and one of our service technicians will help you explore your options when it comes to upgrading your tankless water heating system.