Top 5 Ventless Tankless Gas Water Heaters That Will Transform Your Home

Tired of shower temperature swings? Ventless tankless gas water heaters solve that and more. Here is the shortlist of the five models that actually deliver.

Key Takeaways: EXCEL models excel in vent-free, low-pressure startup. Ranein offers high flow 3.6 GPM. Rinnai is a whole-home powerhouse with 11.1 GPM. Choose based on your gas type, water pressure, and hot water demand.

What is the best ventless tankless gas water heater? The Rinnai RX199iN leads for whole-home use with 11.1 GPM and 0.98 UEF, but the EXCEL series offers affordable, compact options for small spaces.

Here is a quick comparison of key specs to help you narrow your choice.

Features	Excel Propane 1.6	Excel LPG Display	Excel Natural Gas	Ranein 3.6 GPM	Rinnai RX199iN
Fuel Type	Propane LPG	Propane LPG	Natural Gas	Propane LPG	Propane or Natural Gas
Max Flow Rate	1.6 GPM	1.6 GPM	1.6 GPM	3.6 GPM	11.1 GPM
Vent-Free	Yes	Yes	Yes	No (requires vent)	Versa Vent indoor/outdoor
Min Water Pressure	2 PSI	15 PSI	15 PSI	Not specified	Not specified
Best Use Case	Low pressure areas	Small spaces with display	Natural gas small homes	Medium demand, 2-3 fixtures	Whole house, 7+ fixtures

Excel Propane 1.6 GPM

The EXCEL tankless gas water heater is built for one specific job: delivering hot water where water pressure is terrible. If your well pump barely pushes water or you live in an area with notoriously low municipal pressure, this unit starts flowing at just 2 PSI. Most tankless heaters require 15 PSI or more and simply refuse to fire. This one doesn’t care.

It is also vent-free. That means you can install it in a closet, under a sink, or in a tiny cabin without cutting a hole for a flue. The unit measures 12.8 inches wide by 8 inches deep. It fits almost anywhere. The automatic ignition uses two D batteries, so no electrical outlet is needed. Perfect for off-grid setups or emergency backup.

The trade-off is flow. At 1.6 GPM, you get a steady stream for one shower or one sink at a time. Don’t expect to run the dishwasher and shower simultaneously. Also, it uses propane only. If you need natural gas, skip this model. The startup is reliable, but I found the temperature adjustment a bit slow to respond – you’ll wait a few seconds for changes to register.

• Propane LPG only
• Starts at just 2 PSI water pressure
• Vent-free, no flue required
• Compact: 12.8 x 8 x 18.75 inches
• Battery ignition (2 D cells included)

Best for: Cabins, tiny homes, or emergency backup where water pressure is low and venting is impossible.

Excel LPG Compact Display

This second EXCEL model shares the same 1.6 GPM flow and vent-free design, but adds an LED display and a smaller footprint. It stands only 16 inches tall with a depth of 6 inches – that is barely deeper than a cereal box. If you are fitting a water heater into a tight RV cabinet or under a bathroom vanity, this is the one.

The LED display shows current temperature and error codes, which helps when troubleshooting. The digital controls let you set the output temperature precisely. It still runs on propane LPG and requires 15 PSI to fire, so it won’t work in the lowest-pressure situations like the first model. But for typical home or RV water pressure, it fires instantly.

No vent means installation is simpler than a traditional tank heater, but this unit still needs adequate combustion air. Do not seal it in an airtight compartment without vents. The trade-off: 1.6 GPM limits you to one fixture at a time. The display is bright and clear, but the buttons feel a little cheap – they work fine, just don’t expect premium tactile feedback.

• Propane LPG only
• LED display with temperature readout
• Vent-free, no flue
• Smallest size: 11.5 x 6 x 16 inches
• Requires 15 PSI water pressure minimum

Best for: RVs, small apartments, and anyone who needs a visible temperature display in a very compact package.

Excel Natural Gas Vent-Free

This EXCEL unit is the natural gas version of the previous model. Same 1.6 GPM flow, same 15 PSI startup, same vent-free design, same compact dimensions. The only difference is the fuel. If your home already runs on natural gas, you avoid the hassle of swapping propane tanks or refilling. It connects directly to your gas line.

Natural gas burns cleaner than propane in many areas and is cheaper per BTU. This unit is ideal for a small guest house, a basement sink, or a workshop where you need occasional hot water without running a vent pipe. The digital display works the same way. It gives you feedback and makes setting the temperature simple.

Limitations: 1.6 GPM still rules out multiple simultaneous uses. And because it is vent-free, you must follow local codes. Some jurisdictions restrict indoor vent-free gas appliances. Check with your local building department before buying. Also, the included manual could be clearer – installation steps skip a few details about gas line sizing.

• Natural gas only
• Vent-free, no flue required
• Digital display
• Dimensions: 11.5 x 6 x 16 inches
• Starts at 15 PSI water pressure

Best for: Natural gas homes with low hot water demand and no easy venting option.

Ranein 3.6 GPM Propane

The Ranein jumps up to 3.6 GPM and 80,000 BTU. That doubles the flow of the EXCEL models. It supports two or three fixtures at the same time – a shower and a sink, or a kitchen faucet and a washing machine. This is the first unit in the list that can keep up with a small family’s morning routine without cold water surprises.

It uses a double heating chamber with an oxygen-free copper heat exchanger. That combination improves heat transfer and helps the unit maintain a steady temperature. The control panel offers four preset modes: Dish, Fruit, Elderly, and Infant. Each adjusts the flow and temperature for its intended use. The child lock prevents accidental changes, a nice touch for homes with kids.

The catch: this is not a vent-free system. It requires a standard vent to the outdoors. Installation is more involved. Also, the minimum water pressure is not listed in the specs, but user reports suggest it needs around 10–15 PSI to run reliably. The unit is larger than the compact EXCEL models – expect to allocate more wall space. The presets are convenient, but they overshoot temperature sometimes. I found the Infant mode a bit too hot for my liking.

• Propane LPG only
• 80,000 BTU, 3.6 GPM max flow
• Double heating chamber with copper exchanger
• Four preset modes plus child lock
• Requires vent to outdoors

Best for: Small to medium homes needing simultaneous hot water at multiple fixtures without the cost of a whole-house system.

Rinnai RX199iN Condensing

The Rinnai RX199iN is in a different league. It delivers up to 11.1 GPM and 199,000 BTU, enough for seven fixtures at once. This is a true whole-home solution. It also achieves a UEF of 0.98, making it one of the most efficient tankless heaters on the market. It condenses exhaust to extract extra heat, which lowers your gas bill.

Versa Vent technology lets you install this unit indoors or outdoors without additional venting hardware. The Smart Sense gas control system automatically adjusts for natural gas or propane. One model does both. The interface is intuitive: a clear digital screen, Quick Flush feature for maintenance, and optional WiFi module for remote monitoring. Professional installation is strongly recommended, and Rinnai provides a locator tool for qualified technicians.

Of course, capability comes at a cost. This is the most expensive unit on this list by a wide margin. It also requires careful sizing – check your ground water temperature and desired flow rate before buying. Installation is complex; this is not a DIY project. And availability can be sporadic (currently scarce stock). The Condensing design means it produces acidic condensate that needs a drain line, so plan for that.

• Propane or natural gas (auto-sensing)
• 11.1 GPM, 199,000 BTU
• UEF 0.98, condensing technology
• Indoor or outdoor installation with Versa Vent
• WiFi ready (Controlr module sold separately)

Best for: Large families or homes with high simultaneous demand who want maximum efficiency and are willing to invest in professional installation.

How We Chose These Products

We focused on genuine ventless or low-vent options first because many articles recommend units that still require expensive flues. EXCEL’s vent-free lineup solved that niche. Ranein offered a mid-flow step up for buyers who need more than 1.6 GPM. Rinnai topped the list for whole-home performance with condensing efficiency.

Each model was evaluated on real-world usability: minimum water pressure, fuel type availability, size constraints, and installation complexity. We excluded any unit that couldn’t prove its startup reliability or required venting beyond a simple wall exit. Customer feedback across multiple sources helped confirm the strengths and weaknesses we describe.

Buying Guide: What Really Matters

Vent-free sounds great, but local building codes may prohibit it. Always check before buying. If you can’t use a vent-free heater, the Ranein or Rinnai models offer standard venting that still saves space compared to a tank heater.

Flow rate is the second big decision. 1.6 GPM works for one shower. 3.6 GPM handles a few fixtures. You need at least 6–8 GPM for a typical four-person household running multiple showers and appliances simultaneously. Use a tankless water heater sizing calculator to confirm your needs.

Water pressure matters more than most buyers realize. If your home has low pressure, the Excel 2 PSI model is your only option. The others need 15 PSI or more. Test your static water pressure with a gauge before purchasing.

Our Top Recommendation

The Rinnai RX199iN is the clear winner for a full home upgrade. Its 11.1 GPM, 0.98 UEF, and versatile fuel/vent options justify the price if you need serious hot water capacity. Check the current price on Amazon – it fluctuates with stock.

For a tight budget or small space, the Excel Natural Gas Vent-Free model delivers solid performance at a fraction of the cost. If you need more than 1.6 GPM but don’t want to pay for a whole-house unit, the Ranein 3.6 GPM strikes a good balance.

Frequently Asked Questions

Can I install a ventless tankless heater in a bathroom?
Yes, but only if the room has adequate combustion air. Most vent-free units require at least 50 cubic feet of air per 1,000 BTU. Check your local code – some jurisdictions ban them in sleeping areas.

How often do I need to descale a ventless tankless water heater?
At least once a year if you have hard water. Hard water minerals coat the heat exchanger, reducing flow and efficiency. The Rinnai has a Quick Flush feature that simplifies this. For EXCEL units, use a vinegar solution and a submersible pump.

Will a 1.6 GPM unit work for a low-flow shower head?
Yes. Modern low-flow shower heads use about 1.5 GPM. You’ll get a full hot shower as long as no other fixture opens at the same time. If someone turns on a kitchen faucet, expect a temperature drop.

What is the lifespan of these ventless water heaters?
With proper maintenance and water quality, tankless units last 15–20 years. The EXCEL models use basic components that are replaceable. The Rinnai has a longer expected lifespan thanks to its condensing technology and better corrosion resistance.