Best Propane Tankless Water Heater (2026)

Rheem RTGH-95DVLP-3 Condensing Propane Tankless Water Heater

199,900 BTU/h max, 11,000 min · 9.5 GPM at a 35°F rise, 8.5 at 45°F · indoor direct vent, 2- or 3-inch plastic vent · 120 V · 3/4-inch NPT gas, hot and cold · condensing, with a condensate drain · 15-year heat exchanger, 5-year parts, 1-year labor · 52.9 lb

The RTGH is Rheem’s condensing line. Rheem’s spec sheet covers natural gas and propane together (swap the N for a P in the model number). It vents through the wall or roof with plastic pipe, 2-inch up to 60 feet or 3-inch up to 150 feet of straight run. Rheem’s spec sheet, manual and installation guide list different plastics (the manual: Schedule 40 or 80 PVC, CPVC, ABS, listed stainless or InnoFlue polypropylene), so follow the manual and local code. The manual says failure to vent properly will result in death from fire, explosion or carbon monoxide, never to vent through a chimney, to vent it separately from all other appliances, and to inspect the vent terminal, air intake and vent system at start-up and at least annually.

Condensate is acidic. Rheem’s manual says to drain it through PVC, CPVC or flexible tube, not directly into the sewer, and recommends an external neutralizer. For propane, the manual says never to convert the heater from one fuel to the other and recommends gas detectors in LP and natural gas installations. Rheem’s Use and Care manual lists code 12 as gas service interrupted or, on LP models, LP gas running low; our Rheem tankless error codes page gives the flame-loss wording from another Rheem document, so check the propane level first.

• Rheem lists 9.5 GPM at a 35°F rise and 8.5 GPM at 45°F
• Plastic vent: 2-inch to 60 feet or 3-inch to 150 feet of straight run, per Rheem
• Freeze-protection heater to -30°F at the air intake and -4°F ambient, per Rheem (it needs power)
• Sold and shipped by Amazon on September 29, 2026

• Needs a wall or roof vent and a condensate drain, which the outdoor units below do not
• Rheem’s spec sheet, manual and guide list different vent materials
• Rheem says never to convert it, so a natural gas unit cannot be turned into this one
• Rheem’s freeze-protection heater stops working if the power is cut

Verdict: The pick for a house that has propane, a place for a wall vent and a licensed installer. Confirm the model on the box ends in LP-3, not LN-3.

Rheem RTG-84XLP-3 Outdoor Propane Tankless Water Heater

180,000 BTU/h max, 11,000 min · 8.4 GPM at a 35°F rise, 6.7 at 45°F, 5.1 at 67°F · outdoor installation only, no vent pipe · UEF 0.82 · non-condensing, copper heat exchanger · 120 V, hard-wired · 15-year heat exchanger, 5-year parts, 1-year labor

The RTG-84XLP-3 is built for a wall outside the house, so there is no vent pipe to plan. Rheem’s manual says not to install this water heater indoors or in a confined area, because it is designed for outdoor installation only. Rheem’s DANGER box says any other type of installation will result in death or serious personal injury. Our reading is that a closed garage, shed or closet counts as confined. The manual also says LP water heaters should not be installed below grade (for example, in a basement) if federal, state or local laws, rules, regulations or customs prohibit it. Its freeze-protection heater works to about -4°F outside without wind and protects only the internal parts; piping and valves need their own protection.

The smaller RTG-70XLP-3 is the same design at 160,000 BTU/h: Rheem lists 7.0 GPM at a 35°F rise and 6.0 at 45°F. One buying warning: the Amazon listings for these outdoor propane units carry copied text that calls them natural gas and indoor. The titles and model fields say liquid propane and outdoor (XLP). Check that the model on the box says XLP; an XLN is a natural gas unit.

• No vent pipe to plan: Rheem’s manual heads the outdoor install “No Venting Required”
• Rheem lists 8.4 GPM at a 35°F rise and 6.7 GPM at 45°F
• A smaller RTG-70XLP-3 is available at 160,000 BTU/h
• Sold and shipped by Amazon on September 29, 2026

• Outdoor only: Rheem says not indoors or in a confined area
• Rheem lists a lower UEF, 0.82, than the condensing RTGH
• Ships without a power cord: Rheem says to hard-wire it, and another page allows adding a plug
• The Amazon listing text mixes in natural gas and indoor wording

Verdict: The pick if the heater can go on an open outside wall and you want to skip the vent. Follow Rheem’s outdoor-only rule to the letter.

Rinnai RE199iP and RE160iP Non-Condensing Propane Tankless Water Heaters

RE199i: 199,000 BTU/h max, 9.8 GPM maximum flow with parameter adjustment (listing: up to 7.6 GPM) · RE160i: 160,000 BTU/h max, 6.6 GPM with parameter adjustment (listing: up to 6.1 GPM) · 10,400 BTU/h minimum · non-condensing, indoor direct vent with Rinnai-listed vent parts (3-inch/5-inch concentric per the spec sheet) · 120 V · 3/4-inch NPT gas, hot and cold · 15-year heat exchanger (or 12,000 hours), 5-year parts, 1-year labor per the manual

The RE series is Rinnai’s non-condensing line, and Amazon titles the propane version with a P at the end of the model name. It is a direct vent unit, but not with plastic. Rinnai’s manual says not to use PVC, CPVC, ABS or galvanized material to vent it, to use only vent components certified and listed with the model, not to mix components from different makers, and not to common vent it or connect it to an existing vent or chimney. Its spec sheet gives a maximum flow and a curve against temperature rise, not a table, and says maximum flow varies with set temperature, rise and altitude.

Rinnai’s conversion manual (100000784) for the RE and REP models says its kit is installed by a qualified service agency. On September 29, 2026 no Rinnai propane heater was sold by Amazon or Rinnai, so we link two listings from eFaucets, a third-party seller. Its name matches Rinnai’s authorized e-tailer list, and Rinnai’s site says products from unauthorized online dealers carry no Rinnai warranty. The manual excludes an incorrect gas type from coverage. The text on both listings says labor is covered for 5 years with registration inside 90 days; the manual we read lists 1 year. Ask Rinnai which applies.

• Rinnai documents a propane conversion kit and who installs it, for these models
• Heat exchanger warranty of 15 years or 12,000 hours, per the manual
• Freeze protection to -22°F indoors with power and gas on, per the manual
• Rinnai recommends a carbon monoxide alarm near each sleeping area

• The linked listings are third-party, not Rinnai or Amazon
• Vent parts must be Rinnai-listed metal or manufactured components, not PVC
• The manual and the listings disagree on the labor warranty
• The freeze protection depends on power and gas, so an empty propane tank in a freeze removes it (our reading of Rinnai’s wording)

Verdict: The pick if you want a Rinnai, your installer works with listed metal vent, and you will check the seller name against Rinnai’s list. The RE199iP is the bigger unit; the RE160iP suits a smaller house.

Eccotemp SMARTHOME SH22-LP Outdoor Propane Tankless Water Heater

25,000–140,000 BTU/h · 6.8 GPM at a 35°F rise per Eccotemp · 95–140°F setting range · outdoor permanent installation only · 120 V · 3/4-inch NPT gas and water · propane only, 9 to 13 in. w.c. inlet on the rating label · warranty: 10-year heat exchanger and 5-year components on the product page; the manual we read lists 2 and 3 years

The SH22-LP is Eccotemp’s outdoor whole-house propane model with Wi-Fi and an app. Its manual says the SH22 is for outdoor permanent installation only, must be mounted on a vertical wall, and must not be installed indoors or in a confined space. The indoor version is a different model, the SH22-I. The manual says never to try converting the heater from natural gas to propane, and to have a professional connect the gas pipe. The product page says it cannot be used for hydronic, recirculating or floor heating.

The manual says not to use the SH22 in unsafe freezing conditions, and its warranty excludes freeze damage and use in a recirculation loop. Its propane pressure figures conflict (see the pressure table). The Amazon seller is listed as Eccotemp.

• Eccotemp rates it at 6.8 GPM at a 35°F rise
• Outdoor wall mount with no vent pipe, per Eccotemp’s product page
• Eccotemp lists a 95–140°F setting range
• Wi-Fi app, per Eccotemp

• Outdoor only: not for indoors or a confined space
• Eccotemp’s manual lists 13 and 14 inches of water column for the maximum propane pressure
• Needs 0.7 GPM to activate, more than the Rheem’s 0.4 GPM
• The product page lists a 10-year heat exchanger and 5-year components warranty; the manual lists 2 and 3 years. Ask Eccotemp which applies

Verdict: The pick if you want an outdoor propane unit with an app and will have a professional confirm the gas pressure against the rating plate.

Not linked: Eccotemp SMARTHOME SH22-LP — on 10/3/2026 the Amazon listing was sold by a third-party seller, not by Amazon or the maker. We re-check listings every week.

Camplux BD264 and BD158 Portable Propane Tankless Water Heaters

BD264: 68,000 BTU/h, 2.64 GPM per the model name and listing · BD158: 41,000 BTU/h, 1.58 GPM · propane only, 11 in. w.c. inlet with the supplied regulator · cylinder up to 20 lb (not included) · 2 D batteries · outdoors only · 1-year heat exchanger and parts warranty

These are portable outdoor heaters for camp showers and off-grid wash stations, not small whole-house units. Camplux’s manual says to use the heater outdoors only and never in an enclosed space such as a camper, tent, car or home, because it can produce carbon monoxide, which has no odor. It says not to use it in caravans, tents, marine craft, cars, mobile homes or similar locations, not to leave it unattended, and not to use it in high wind. It is for non-potable water such as a portable shower, for point-of-use temporary water heating, and not for a permanent inlet water connection or for supplying multiple outlets. The use section adds that it cannot be permanently mounted or plumbed in any way. Other pages describe wall mounting, which contradicts that, so we follow the stricter warning.

The listing names camping, tiny home and RV among the uses. A portable shower outside next to an RV fits the manual; an RV or tiny home plumbing system does not. The manual says safe use and storage need a temperature above 32°F, to drain the heater through the drain plug after each use near freezing, and to use only the regulator and hose supplied. It needs about 0.44 GPM and 3.6 psi to run, and gas detectors are recommended. The manual covers BD158 and BD264; the listings carry longer model names (BD158NC, BD264C N1), so confirm with Camplux that it applies. The seller is listed as Camplux.

• Camplux’s manual states the outdoor-only, non-potable, temporary-use limits clearly
• Regulator and hose supplied for a propane cylinder of up to 20 lb, per the manual
• Two sizes: 41,000 and 68,000 BTU/h
• Removable drain plug for freezing weather, per the manual

• Not for a house, an RV plumbing system or any permanent water connection, per the manual
• Non-potable water only, per the manual
• Warranty is 1 year on the heat exchanger and on parts, per the manual
• The listing model names do not exactly match the manual’s BD158 and BD264

Verdict: The pick for a camp shower or off-grid outdoor wash station, used outside, with a propane cylinder. Not a substitute for a water heater in a home or an RV.