Continuous flow water heaters provide instant, on-demand hot water without the standby losses of traditional tanks. This guide highlights five top options ideal for different homes and usage patterns. Best for larger households with simultaneous hot water needs, best for gas-fueled outdoor setups, best for compact spaces, and best-value electric models for multi-point use. Each product is evaluated for capacity, control features, and practicality in real-world applications.
APUS 27kW Tankless Electric Quick-Heat System
Powerful electric on-demand hot water with memory and LED display. Delivers up to 6.5 GPM, making it suitable for 3-4 simultaneous uses. Best for larger homes or multi-point residential use where a quick recovery is needed. Temperature can be set from 86°F to 140°F in 1°F increments, and the memory function recalls the last setting to simplify daily use. Self-modulating technology reduces electricity use by adjusting output to real-time demand. Caution: Actual flow varies with inlet water temperature and household demand; ensure an appropriate electrical circuit and safe installation by a qualified technician.
Rheem RTG Series 8.4 GPM Gas Tankless Outdoor
High-capacity natural gas tankless unit designed for whole-house use. Provides about 8.4 GPM at typical temperature rise, with an outdoor installation to simplify venting. Energy-efficient non-condensing design and 180,000 BTU/hr output suit large families with multiple showers. Best for outdoor installations where venting is feasible and a robust hot-water supply is needed. Caution: Outdoor deployment requires weather protection and professional installation; gas lines and venting must comply with local codes.
Westinghouse 14kW Electric Tankless Water Heater
Compact electric model with WiFi and temperature memory. Delivers hot water quickly, and supports two simultaneous points with a 0.53–3.4 GPM range depending on inlet temperature. Smart features include compatibility with Alexa/Google Home for remote control. Best for small homes or apartments needing smart control and space-saving installation. Limitation: 14kW capacity may limit simultaneous usage in households with higher hot-water demand.
FOGATTI Indoor Tankless Gas Water Heater
Indoor gas tankless unit with 120,000 BTU and 5.1 GPM flow. Four-stage combustion and advanced temperature control keep water within a tight ±1°F range. Suitable for 2–4 outlets and multitasking households. Best for reliable gas-powered on-demand hot water with precise temperature control. Caution: Gas installation requires professional service and venting considerations; ensure combustibles are clear and codes are followed.
110V Electric Tankless Water Heater, 3kW
Compact 110V electric tankless unit with 3000W power and LED display. ETL-listed with 98% thermal efficiency. Suitable for under-sink or small-space installations where wall-mounting frees up cabinet space. Best for single-point use or small apartments; use caution in homes with higher hot-water needs due to lower GPM and limited power supply.
VELPAX Propane Tankless Outdoor Water Heater
Outdoor propane tankless unit delivering 18L/4.76 GPM with 82,000 BTU/h and a 5-mode shower head. Suitable for RVs, camping, cabins, and outdoor use. Best for portable or outdoor hot-water needs; compact design allows flexible placement. Caution: Outdoor units require weatherproofing and stable gas supply; ensure camping or off-grid setups meet local safety standards.
VEVOR Propane Tankless Water Heater, 100,000 BTU
Propane-powered tankless heater with 100,000 BTU/h, designed for indoor use with multiple security protections and a LED display. Provides on-demand hot water for whole-house use and emphasizes precise temperature control. Best for homes seeking a propane solution with smart temperature management. Caution: Installation requires proper venting and adherence to safety guidelines for indoor propane appliances.
Buying Guide: Choosing The Right Continuous Flow Water Heater
- How to match capacity to your home: Assess peak simultaneous hot-water demand (showers, sinks, appliances) and select GPM accordingly. Higher GPM models fit larger homes or busy households.
- Power source considerations: Electric units require adequate electrical service and proper circuit protection. Gas units require venting and gas line compatibility. Outdoor units often simplify venting but require weather protection.
- Space and installation: Tankless units save space but installation complexity varies. Wall-mounted designs benefit smaller spaces; ensure clearances, access for service, and professional installation when required.
- Control and efficiency features: Look for self-modulating or memory functions, digital temperature control, and smart-home compatibility to optimize energy use and comfort.
- Safety and maintenance: Consider protections against dry firing, overheating, and leaks. Regular inspection of gas lines, venting, and electrical connections is recommended.
- Local codes and certifications: Ensure the model complies with local building codes and safety standards. CSA, ETL, and UEF ratings indicate compliance and efficiency.
Frequently Asked Questions
- What is a continuous flow water heater?
A continuous flow water heater heats water on demand as it flows through the unit, eliminating storage tanks and standby heat loss.
- How many showers can one unit support?
Depends on the unit’s GPM rating and incoming water temperature. Higher GPM models support multiple points of use simultaneously.
- Do I need professional installation?
Yes, especially for gas models or units requiring electrical upgrades and proper venting for safety and code compliance.
- Are electric tankless heaters efficient?
Yes, many feature self-modulating technology and precise temperature control to minimize energy use.
- Can these units be used in apartments?
Yes, compact electric models are well-suited for apartments, provided electrical capacity and space are appropriate.
- What maintenance is required?
Regularly inspect connections, flush the unit if the manufacturer recommends, and verify venting and drainage for gas units.