Size Your Water Heater. Tank or Tankless?
Tell us your household and we'll estimate the First-Hour Rating you need, a rough tank size, a Gulf Coast tankless GPM target, and which type fits your home — using DOE and Consumer Reports figures, not sales math.
- 01Master Plumber MP-4462
- 02Upfront pricing
- 032-year repair warranty
Right-size it in a few taps.
Adjust the sliders and your recommendation updates instantly. We use the U.S. Department of Energy First-Hour Rating worksheet — the hot water your busiest hour actually draws — and size tankless in GPM at the warm ~50°F Gulf Coast temperature rise.
Target First-Hour Rating
75
gallons/hour · aim for 60–80 gal/hr
Rough tank size
50 gal gas / 66–80 gal electric
Match the FHR, not just the gallons on the label.
Tankless target
3.7 GPM
at ~50°F Gulf Coast rise · 1 shower + 1 faucet
How we estimated your peak hour
DOE First-Hour Rating worksheet — the hot water your busiest hour draws, using DOE per-use gallons.
- 2 showers40 gal
- 1 bath (tub fill)20 gal
- Hand & face washing8 gal
- Shaving (2)4 gal
- Kitchen / food prep3 gal
- Recommended FHR≈ 75 gal/hr
Tank vs. tankless
Typical national 2026 figures for education — not a Streamlined Plumbing quote. Sources: U.S. DOE, Consumer Reports, EIA.
Storage tank
- Lifespan
- 8–12 yr (gas) · 10–15 yr (electric)
- Efficiency
- Baseline — reheats stored water 24/7
- Installed cost (2026)
- Gas $1,200–$2,500 · Electric $1,000–$2,200
- Trade-offs
- Lower up-front cost, simple to service — but can run out of hot water and takes floor space.
Tankless
Best for you- Lifespan
- 15–20+ yr
- Efficiency
- 24–34% more efficient for homes using ≤41 gal/day (8–14% at high use) — DOE. Water heating ≈ 20% of home energy (EIA), so typical savings run $80–$200/year.
- Installed cost (2026)
- Gas $3,000–$6,000 · Electric $1,500–$4,000
- Trade-offs
- Endless hot water, longer life, saves space — but higher up front and needs an annual descaling/flush ($100–$200), especially on hard water.
Best for your home
Either type can cover this demand. Because Gulf Coast inlet water is warm (~50°F rise), tankless hits its GPM target easily here — and its 15–20+ year life and endless hot water often make it the better long-run value for a home like yours. A right-sized tank is the lower up-front option.
Payback is best on new construction or a vacation rental (3–6 yr) and slowest when replacing a tank that still works (12–17 yr). Federal 25C tax credits expired 12/31/2025 — we don't promise any rebate.
Want it sized right the first time?
Master Plumber Brandon Byrd (MP-4462) sizes your water heater to your real peak demand, gives you an upfront price, and backs the install with a 2-year repair warranty. Phone-first — call and we'll talk it through.
Related services: Water Heater Services · Tankless Water Heaters
No tank. No closet. Endless hot water.
This is one of our tankless installs — a wall-mounted unit with isolation valves set for easy annual flushing. A tankless heats water only as it flows, so there's no standby loss and no 40-gallon tank taking up a closet. Per the DOE they run 24–34% more efficient for homes using 41 gallons a day or less, and typically last 15–20+ years versus 8–12 for a tank.
They do need a yearly descale to stay efficient and keep the warranty intact — we handle that too.
Next steps for your water heater.
Water Heater Sizing — Frequently Asked Questions
What is First-Hour Rating (FHR) and why does it matter more than tank size?
First-Hour Rating is the number of gallons of hot water a heater can deliver during a busy hour, starting with a full tank. The U.S. Department of Energy recommends sizing by FHR — your peak-hour demand — not by tank gallons alone, because a small, fast-recovery unit can out-perform a bigger, slower one. This tool estimates your peak-hour draw from DOE per-use gallon figures, then points you at the FHR band that covers it.How is tankless sized here for the Gulf Coast?
Tankless heaters are sized by flow rate (gallons per minute) at a given temperature rise, not by gallons stored. On the Gulf Coast the incoming water is warm — roughly 70°F — so heating it to a 120°F shower means only about a 50°F rise. That warm-climate advantage lets a tankless unit hit a higher GPM here than the same unit could up north. We sum the fixtures likely to run at once to give you a realistic GPM target.Is tank or tankless better for my home?
It depends on your peak demand and how long you plan to keep the home. Tankless costs more up front but lasts 15–20+ years, never runs out of hot water, and (per DOE) runs 24–34% more efficient for homes using 41 gallons a day or less — often $80–$200 a year in savings (EIA). A right-sized tank is the lower up-front option. The tool gives a 'best for you' note, and Master Plumber Brandon Byrd will give you the straight answer for your home.Are these your prices?
No. The lifespan, efficiency, and installed-cost ranges shown are typical national 2026 figures from the DOE, Consumer Reports, and the EIA, provided for education so you can read any quote informed — not a Streamlined Plumbing quote. Your price depends on the unit, fuel type, and any code or venting work. We give you an upfront, itemized price before any work starts. Note: the federal 25C tax credit expired 12/31/2025, so we don't promise any rebate.Do tankless water heaters need maintenance?
Yes. Tankless units should be descaled and flushed once a year (about $100–$200), especially on the harder water common along the coast, to keep them efficient and protect the warranty. Streamlined Plumbing offers tankless cleaning and service — call (251) 423-7654.
Sized Right, Priced Upfront.
Whether it's a tank or tankless, Master Plumber Brandon Byrd (MP-4462) sizes it to your real demand and gives you a straight repair-or-replace answer — backed by a 2-year repair warranty.
Real Streamlined work