Quick Answer: The best Eccotemp tankless water heater depends entirely on the install. For a whole-home replacement, the Builder Series 6.8GB (6.8 GPM natural gas or propane, roughly $558–$719 at Home Depot depending on fuel and venting) is the pick. For a single small home, apartment, or cabin, the indoor i12 (4.0 GPM, 80,000 BTU, roughly $335–$385) needs only a vent kit and a gas line. For off-grid, camping, or backup use with zero electrical hookup, the portable L10 (3.0 GPM, 75,000 BTU, roughly $319–$399) runs on 2 D-cell batteries alone. Eccotemp’s whole game is undercutting Rinnai, Rheem, and Navien on price — its tradeoff is a shorter warranty, typically 1–3 years versus 12–15 on the premium brands.
Eccotemp built its name on the portable propane heaters that off-grid cabins, tiny houses, and mobile homes rely on — see our best RV tankless water heater and best tankless water heater for tiny house guides for that side of the lineup. But Eccotemp also sells a full whole-home Builder Series that competes directly with Rinnai and Rheem on price, and a mid-size indoor unit for apartments and small homes. This guide ranks the three model families side by side so you can match the right Eccotemp to your gas line, your panel, and your budget — not just whichever one shows up first in a search.
Last updated August 25, 2026 — re-checked against Home Depot, Walmart, and eccotemp.com. The 6.8GB-ING indoor natural-gas Builder Series jumped from about $580 to $719 (marked down from an $829 list, per eccotemp.com); the i12 dropped from about $489 to $335–$385 (Walmart lists NG at $369 and LP at $334.29, Home Depot’s NG listing runs similarly after its current promo). The 6.8GB-LP outdoor propane price and L10 pricing are unchanged.
Our top picks at a glance
| Model | Best for | Fuel | Flow / BTU | Power needed | Price |
|---|---|---|---|---|---|
| Eccotemp Builder Series 6.8GB | Whole-home replacement | NG or LP | 6.8 GPM / up to 199,000 BTU* | 120V outlet | ~$558–$719 |
| Eccotemp i12 | Small home / apartment | LP or NG | 4.0 GPM / 80,000 BTU | 120V outlet + vent kit | ~$335–$385 |
| Eccotemp L10 | Off-grid / portable / backup | LP only | 3.0 GPM / 75,000 BTU | 2 D-cell batteries, no wiring | ~$319–$399 |
*BTU varies by 6.8GB configuration (indoor vs. outdoor, NG vs. LP); Home Depot lists the indoor natural-gas 6.8GB-ING and outdoor liquid-propane 6.8GB-LP at 6.8 GPM.
By the numbers
- 6.8 GPM on the Builder Series 6.8GB — enough for 3–4 simultaneous fixtures at a warm inlet, per Eccotemp’s own product specifications.
- 79% Energy Factor on the portable L10, per Eccotemp’s published spec sheet — lower than a condensing whole-home unit, but the L10 isn’t competing on efficiency, it’s competing on zero-electricity portability.
- 24–34% more energy efficient than a standard storage tank for a home using up to ~41 gallons of hot water a day, per the U.S. Department of Energy — the baseline efficiency case for any tankless heater, Eccotemp included, over a conventional tank.
- 1–3 years typical component warranty on Eccotemp residential units (chamber body vs. circuit board vs. other parts carry different terms), per Eccotemp’s own warranty documentation — noticeably shorter than the 12–15-year heat-exchanger warranties common on Rinnai and Navien.
1. Eccotemp Builder Series 6.8GB — Best Whole-Home
Eccotemp Builder Series 6.8GB (Indoor/Outdoor, NG or LP)
- Eccotemp's largest current residential line, built to replace a tank heater in a 2–3 bathroom home without the Rinnai/Rheem/Navien price tag.
- Sold in indoor and outdoor versions, each in natural-gas or liquid-propane fuel — pick the SKU that matches your existing gas line and venting situation.
- 6.8 GPM at a warm inlet handles 3–4 fixtures at once; expect noticeably less in a cold winter, same as any non-condensing gas tankless unit.
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The 6.8GB is the Eccotemp to buy if you’re replacing a tank water heater for an entire house and want to spend less than a Rinnai or Rheem. Home Depot and eccotemp.com price the indoor natural-gas 6.8GB-ING around $719 (marked down from an $829 list) and the outdoor liquid-propane 6.8GB-LP around $558 — both still under the $700–$900+ street price of a comparable Rinnai or Rheem whole-home unit, though the NG/indoor configuration’s price gap has narrowed since our last check. The tradeoff is warranty length and brand support network: Eccotemp’s residential coverage runs years, not the 12–15-year heat-exchanger terms the premium brands offer. If your home has a straightforward gas line and you want the lowest whole-home price on the market, this is the pick; if you want the longest warranty and widest installer familiarity, budget more for a Rinnai Sensei or Navien instead.
2. Eccotemp i12 — Best Small Home / Apartment
Eccotemp i12 Indoor Tankless Water Heater
- Wall-mounted indoor unit sized for a single-family small home, apartment, condo, or cabin — one to two fixtures at once.
- Ships with a horizontal vent kit; still needs a proper Category III stainless vent run to code, unlike the battery-only L10.
- Runs on a standard 110/120V outlet for ignition and controls — no heavy electrical service required, only a vent and a gas line.
The i12 sits between the whole-home 6.8GB and the portable L10: it’s a real indoor, vented gas heater — not a portable unit — but sized and priced for a single small home rather than a large family house. At 4.0 GPM and 80,000 BTU it covers a shower plus a sink comfortably, which makes it a fit for a one-bath house, an ADU, or a small cabin with a permanent gas line. If your dwelling is specifically a tiny house, mobile home, or conversion van on a 30-amp electrical service, compare it against the fan-cooled Eccotemp FVI12 first — the FVI12 is Eccotemp’s purpose-built model for those tighter electrical budgets and draws even less power for its ignition and fan.
3. Eccotemp L10 — Best Off-Grid / Portable / Backup
Eccotemp L10 Portable Outdoor Tankless Water Heater
- No 120V outlet needed anywhere — ignition runs entirely on 2 D-cell batteries, so it works at a campsite, cabin, or job site with zero wiring.
- Connects to a standard 20 lb. propane tank and a garden hose; a safety shut-off trips after 20 minutes of continuous run or a 45° tilt.
- Outdoor use only, no freeze protection — drain and store it once temperatures approach freezing.
The L10 is Eccotemp’s best-known model, and it earns that reputation by solving a problem the whole-home brands don’t even try to: hot water with zero electrical hookup. It’s the right call for an outdoor camp shower, a dog-wash station, backup hot water during a power outage, or a hunting cabin with no service panel at all — see our best outdoor tankless water heater, best propane tankless water heater, and best Camplux tankless water heater guides for how it stacks up against Rinnai and Camplux in the same portable category. What it isn’t is a whole-house heater: 3.0 GPM and 75,000 BTU cover one fixture at a time, and there’s no freeze protection, so it needs to come indoors once winter hits.
How to choose an Eccotemp tankless water heater
- Whole house, existing gas line: the Builder Series 6.8GB — lowest whole-home price in this roundup, indoor or outdoor, NG or LP.
- One small home, apartment, or cabin with permanent gas and venting: the i12 — a real vented indoor unit sized for one to two fixtures.
- No electricity at all — cabin, camp, off-grid, or backup: the L10 — the only model here that needs neither a wired outlet nor a vent run.
- Tiny house or mobile home on a 30-amp electrical service: skip this roundup’s picks and go straight to the fan-cooled FVI12, Eccotemp’s model built specifically for that constraint.
- Weigh the warranty gap. Eccotemp’s 1–3 year residential coverage is real money saved up front against a real risk later; if a 12–15-year heat exchanger warranty matters more to you than price, compare against Rinnai or Navien before you buy.
The bottom line
Eccotemp’s value is clearest at the edges of the market the flagship brands ignore: the L10 for zero-electricity portable hot water, and increasingly the Builder Series 6.8GB for homeowners who want a whole-home gas tankless heater without a Rinnai or Rheem price tag. The i12 fills the gap in between for a single small home or apartment. Whichever you pick, match it to your gas line and electrical situation first — GPM second — and go in knowing Eccotemp’s warranty is measured in a few years, not over a decade. Comparing fuel types before you commit to any brand? Start with our best tankless water heater roundup or tankless vs tank guide.