The Tankless Hot Water Heaters That Work Best for Small Spaces: Providing Compact Solutions for Tight Footprints

Our Pick and How the List Was Built

The Rinnai V75IN Tankless Hot Water Heater is the best Tankless Hot Water Heater for small spaces because it provides a high 7.5 GPM flow rate in a compact indoor design.

Finding a water heater that provides consistent heat without consuming excessive floor space often forces a compromise between unit size and flow capacity. Small footprints can lead to “cold water mid-shower” if the unit cannot keep up with demand, making the selection process difficult for those with limited utility room space.

The Rinnai V75IN Tankless Hot Water Heater solves this by delivering 7.5 GPM of hot water while maintaining a compact profile for indoor use. You should choose the Noritz NRC66DVNG if you require a high-efficiency condensing model, or the ECOTOUCH 8kW 240V Instant Water Heater if you need a budget-friendly electric point-of-use solution.

We evaluated the tankless water heater installation options we track against this topic’s criteria to provide these recommendations. The selected products cover a price range from $136.99 to $1091.16, with a median price of $1091.16 across the 10 models in our comparison.

You can find a detailed performance breakdown in our full Rinnai RLX94iN review to see if it fits your space.

Full Comparison Table

Prices are approximate and move frequently – check the current price before deciding. “Not stated” means the manufacturer listing does not give that figure – we do not estimate it.

Our Picks Examined One by One

The 3 picks below run from $136.99 to $1091.16, reviewed in rank order.

Rinnai V75IN Tankless Hot Water Heater

The Rinnai V75IN made this list because it provides a high-performance gas solution for small spaces, offering a flow rate of 7.5 GPM. This capacity allows for multiple simultaneous uses, such as running a shower and a sink at once, which is a significant advantage for compact residential layouts.

What we like: The Rinnai V75IN offers a 7.5 GPM flow rate, which exceeds the 3.5 GPM threshold required for a standard shower head. It also includes a 10-year residential factory warranty on the heat exchanger and a 5-year warranty on labor. The unit is designed for indoor installation and features enhanced scale detection to maintain performance.

Keep in mind: This unit requires a professional installation and a dedicated natural gas supply. You must confirm your gas line size can support the unit’s requirements before purchasing, as high-flow gas heaters require specific infrastructure.

Noritz NRC66DVNG Indoor Condensing Tankless Hot Water Heater

The Noritz NRC66DVNG is included for its high-efficiency condensing technology and compact footprint. It provides a 6.6 GPM flow rate, making it a capable choice for users who need consistent hot water without a large tank.

What we like: The Noritz NRC66DVNG features a 6.6 GPM flow rate and a high-efficiency condensing design. It includes a remote thermostat and a 6-foot power cord for convenient control. The unit is priced at around $489.99, offering a lower entry point for a condensing model.

Keep in mind: This model requires venting with Schedule 40 PVC pipe and fitting. You must verify that your space allows for the specific venting path required by this condensing unit.

ECOTOUCH 8kW 240V Instant Water Heater

The ECOTOUCH 8kW 240V Instant Water Heater is the primary choice for ultra-compact spaces or as a point-of-use supplement. It uses an electric 8kW heating element to provide instant hot water for specific fixtures like a sink faucet.

What we like: The ECOTOUCH 8kW 240V Instant Water Heater is a budget-friendly option at around $136.99. It features self-modulation technology and a cast aluminum heater designed to prevent corrosion. The unit is a viable alternative to 3.5kW heaters for point-of-use applications.

Keep in mind: This 8kW unit requires a 240V electrical connection, which may not be available in all small apartments or studios. You must confirm your electrical panel can support a dedicated circuit for this heater before ordering.

New owners can learn the different types of tankless water heaters available on the market today.

How to Choose a Tankless Water Heater Installation

Dimensions and Footprint

Dimensions and footprint determine if the unit fits within your available wall space or under a cabinet. For small spaces, prioritize the compact design of the ECOTOUCH 8kW 240V Instant Water Heater, which serves as a point-of-use solution for sink faucets. The Rinnai V75IN and Noritz NRC66DVNG offer larger footprints suitable for primary showers but remain compact enough for utility areas. Because these units vary significantly in size, you must measure your mounting area before ordering to ensure the unit and its associated plumbing can fit.

Mounting Orientation

Mounting orientation depends on whether your space allows for vertical or horizontal placement. The Rinnai V75IN and Noritz NRC66DVNG are designed for standard indoor installation, typically on a wall or dedicated mounting surface. The ECOTOUCH 8kW 240V Instant Water Heater is an inline supplement or point-of-use model, offering more flexibility in orientation for small fixtures. Confirm your mounting surface can support the weight of the unit before a qualified installer begins the work.

Ventilation Requirements

Ventilation requirements differ based on the fuel source of the heater. The Rinnai V75IN and Noritz NRC66DVNG use natural gas and require specific venting, with the Noritz model featuring a high-efficiency condensing design that vents with Schedule 40 PVC Pipe and Fitting. The ECOTOUCH 8kW 240V Instant Water Heater is electric and does not require gas venting. Because improper venting creates carbon monoxide hazards, a qualified installer must verify your local building codes and venting path before installation.

Minimum Clearance Needs

Minimum clearance needs involve the buffer zones required for safety and maintenance. While the ECOTOUCH 8kW 240V Instant Water Heater has a compact design for sink use, you must check the manufacturer’s specific clearance requirements for the cast aluminum heater body. The Rinnai V75IN and Noritz NRC66DVNG require space for both the unit and the venting system. For these gas models, the Rinnai V75IN separated the field by offering a flow rate of up to 7.5 GPM, but you must ensure your space allows for the necessary clearance to maintain the heat exchanger and vent lines. These units provide instant heating on demand, meaning there is no waiting time for hot water once the flow begins.

Make sure your installation meets code by viewing the required certifications and safety standards for these units.

What You Need vs What These Picks Deliver

Match the job you actually need done to what it requires, then check whether anything on this page reaches that level. Where nothing does, the row says so.

Thresholds are the levels this category is generally held to, not manufacturer claims. Check them against your own workload before buying.

Who Buys Tankless Water Heater Installations, and What It Really Costs

What Buyers Still Want to Know

Is it cheaper to buy a compact unit or pay for a professional installation?

The cost of professional installation often exceeds the hardware price for compact units due to specialized gas line and venting requirements. You should confirm your local labor rates and specific venting needs before purchasing a model like the Rinnai V75IN or Noritz NRC66DVNG, as these gas units require a qualified installer to meet safety codes.

What happens if the unit loses power or gas during a heavy usage period?

Tankless units like the Rinnai V75IN or Noritz NRC66DVNG can cycle off if the fuel source cannot maintain the required flow rate under heavy demand. If the gas supply fluctuates or the power fails, the unit may stop heating water until the demand stabilizes or the supply is restored.

Which model is best for a sink faucet?

You should choose the ECOTOUCH 8kW 240V Instant Water Heater for a sink faucet because it is a point-of-use model designed for specific fixtures. This electric unit costs around $136.99 and provides a compact solution for small spaces where a full-house system is unnecessary.

Does the Rinnai V75IN provide enough flow for multiple fixtures?

Yes, the Rinnai V75IN provides a flow rate of up to 7.5 GPM, which allows it to serve up to 5 appliances at once. This capacity ensures that the unit can handle simultaneous demand without a significant drop in temperature.

Who Should Skip These Tankless Water Heater Installations

If you need to supply multiple high-demand fixtures simultaneously, such as running two showers and a sink at once, you need a system that meets the 10 GPM threshold. None of the units in our comparison reach this flow rate. These options are sized for small spaces and limited fixture counts.