Quick Answer: The best gas tankless water heater for most homes is the Rinnai RU199iN — a condensing 199,000 BTU unit rated up to 11 GPM at a 0.96 UEF, with WiFi and a 12-year warranty, usually priced below the comparable Navien. Want instant hot water? The Navien NPE-240A2 has a built-in recirculation pump and a 15-year warranty. The Rheem RTGH-95DVLN and retail Rheem Performance Platinum 9.5 GPM are strong value picks, and the Takagi T-H3-DV-N is a great mid-price condensing unit. Every GPM figure assumes a warm inlet — cold winter water lowers real flow.
Gas tankless water heaters deliver much higher flow than electric, which is why they’re the default for larger households, multiple bathrooms, and cold climates. We compared the top natural gas and propane units on flow rate (GPM), efficiency (UEF), warranty, and price — and separated the DIY-friendly retail models from the pro-installed lines so you buy the right one for your install.
Our top picks at a glance
| Model | Best for | Type | Max Flow / BTU | UEF | Warranty | Price |
|---|---|---|---|---|---|---|
| Rinnai RU199iN | Best overall | Condensing | ~11 GPM · 199k | 0.96 | 12 yr | ~$1,600 |
| Navien NPE-240A2 | Best recirculation | Condensing | ~11.2 GPM · 199k | 0.97 | 15 yr | ~$1,500 |
| Rheem RTGH-95DVLN-3 | Best price-to-BTU | Condensing | 9.5 GPM · 199.9k | ~0.94 | 12 yr | ~$1,250 |
| Takagi T-H3-DV-N | Best mid-price | Condensing | 10 GPM · 199k | High-eff | 15 yr | ~$1,250 |
| Rheem Performance Platinum 9.5 | Best retail/DIY value | Condensing | 9.5 GPM · 199k | ENERGY STAR | 12 yr | ~$1,150 |
1. Rinnai RU199iN — Best Overall
Rinnai RU199iN Condensing Gas Tankless
- 199,000 BTU condensing burner rated up to ~11 GPM — comfortably runs 2–3 fixtures at once.
- 0.96 UEF with inexpensive PVC venting; built-in Control-R WiFi.
- 12-year heat-exchanger warranty and typically $100–$300 cheaper than the Navien.
The RU199iN sits atop Rinnai’s condensing RU Series (above the mid-tier RL and entry RE lines) and is the gas unit we recommend to most homeowners. It hits the sweet spot of flow, efficiency, warranty, and price, and the WiFi control is genuinely useful for setting schedules and vacation mode. Match the SKU to your setup — natural gas vs. propane, indoor vs. outdoor — and note Rinnai has rebranded part of this line as RX199iN in some channels.
2. Navien NPE-240A2 — Best With Recirculation
Navien NPE-240A2 Condensing Gas Tankless
- ComfortFlow built-in recirculation pump and buffer tank shorten the wait for hot water.
- Up to ~11.2 GPM at a 0.96–0.97 UEF — top-tier flow and efficiency.
- Class-leading 15-year heat-exchanger warranty.
Navien’s headline advantages are the built-in recirculation (which tames the “cold-water sandwich” and cuts the wait at distant taps) and the longest warranty here. If instant hot water and maximum coverage matter more than saving a couple hundred dollars, the NPE-240A2 is the one to get.
3. Rheem RTGH-95DVLN-3 — Best Price-to-BTU
Rheem RTGH-95DVLN-3 Condensing Gas Tankless
- Nearly 200,000 BTU and 9.5 GPM for hundreds less than the Rinnai or Navien.
- Condensing efficiency (~0.94 EF) with direct-vent PVC.
- Rheem's pro RTGH line — reliable and widely serviced.
The pro RTGH series is Rheem’s performance line (distinct from the retail Performance Platinum SKUs). The RTGH-95DVLN-3 gives you near-flagship BTU and 9.5 GPM at a noticeably lower price — the best price-to-BTU ratio in this roundup for a whole-home condensing unit.
4. Takagi T-H3-DV-N — Best Mid-Price
Takagi T-H3-DV-N Condensing Gas Tankless
- 10 GPM and 199,000 BTU — strong flow for a family of 4–5.
- ENERGY STAR condensing efficiency from a respected pro brand (part of the Rinnai family).
- 15-year heat-exchanger warranty.
Takagi (owned by Rinnai) offers pro-grade condensing units at value pricing. The T-H3-DV-N pairs 10 GPM and a 15-year warranty for around the same money as the Rheem RTGH — an excellent choice for a mid-size family that wants a workhorse without the flagship badge.
5. Rheem Performance Platinum 9.5 GPM — Best Retail / DIY Value
Rheem Performance Platinum 9.5 GPM (ECOH200) Gas Tankless
- Condensing 199,000 BTU, 9.5 GPM, ENERGY STAR certified with EcoNet WiFi.
- Convertible for indoor or outdoor installation.
- Sold at major retailers — the easiest premium gas unit to buy and get parts for yourself.
Rheem’s retail Performance Platinum “ECOH” line brings condensing efficiency, WiFi, and 9.5 GPM to the home-improvement aisle at the lowest price here. Don’t confuse it with the pro RTGH series — it’s the same idea packaged for retail buyers and DIY-friendly installs. It’s our value pick for a whole-home gas upgrade.
How to choose a gas tankless water heater
- Condensing vs non-condensing: Condensing (~0.93–0.97 UEF, PVC venting) costs more upfront but runs cheaper and vents cheaper. Non-condensing (~0.81–0.82 UEF) is cheaper to buy but needs stainless venting.
- Size by GPM: Most 2–3 bath homes want 7–9 GPM at peak; a 199k BTU unit covers that in most climates. Cold inlet water lowers real flow, so size up in the North.
- Natural gas vs propane: Buy the correct fuel SKU (or a convertible model) — they are not interchangeable without a conversion kit.
- Recirculation: Want instant hot water at far taps? Choose a unit with built-in recirculation (Navien) or plan to add a recirc line.
- Gas line & venting: A 199k BTU unit may need a 3/4” gas line and proper venting. Get an installer to confirm before you buy.
The bottom line
For most homes, the Rinnai RU199iN is the best gas tankless water heater: 11 GPM, condensing efficiency, WiFi, and a lower price than the comparable Navien. If instant hot water is the goal, the Navien NPE-240A2 adds built-in recirculation and a 15-year warranty. For the best value, the Rheem RTGH-95DVLN (pro) and Performance Platinum 9.5 GPM (retail) deliver near-flagship performance for less. No gas line? See our electric tankless picks — or weigh the two in our electric vs gas comparison.