When you need reliable, on-demand hot water without a bulky storage tank, non-condensing tankless water heaters are a strong choice. This guide highlights five top options, focusing on outdoor and indoor models suitable for families and multi-bath homes. Each option is evaluated for where it shines, who should consider it, and practical limitations to watch for. Below is a quick buyer’s table to compare core details at a glance.
| Product | Best For | Key Benefit |
|---|---|---|
| Rinnai RE160eP | Outdoor installations; compact spaces | Endless hot water up to 6.1 GPM |
| Rheem RTG 7.0 GPM Natural Gas | Large homes; outdoor use | High flow and efficiency for multi-showers |
| Rheem RTG 7.0 GPM Liquid Propane | Gas LPG setups; diverse outdoor locations | Same high performance with LP fuel |
| MIZUDO 120,000 BTU | Flexible indoor/outdoor; smart control | WiFi/app control with temperature stability |
| Rheem RTG 7.0 GPM Indoor | Indoor spaces; direct venting | Compact, space-saving design for multi-point use |
Note: This comparison focuses on non-condensing models suitable for whole-house use. The best choice depends on fuel type (natural gas vs. propane), installation location, and the number of simultaneous hot-water points you expect to operate.
Rinnai RE160eP Non-Condensing Outdoor Propane Tankless
Best for compact outdoor spaces and households needing reliable hot water without a storage tank. This unit heats water only when needed, reducing energy use. It can provide up to 6.1 GPM, which supports up to about five fixtures at once in typical settings. The LED screen shows service reminders and error codes to simplify maintenance. It includes various residential guarantees for heat exchanger, labor, and parts, signaling durability. A potential limitation is the need for outdoor installation and its non-condensing design, which may affect venting considerations in some climates. Best for small-loot outdoor setups where space is limited and propane supply is readily available.
Rheem RTG Series 7.0 GPM Natural Gas Outdoor
Best for larger homes or multi-bath households that require generous flow outdoors. This model delivers about 7.0 GPM with 160,000 BTU/hr, supporting multiple showers simultaneously at a 35°F rise. It is energy-efficient for a non-condensing gas unit and vents outdoors, offering a straightforward outdoor installation. Choose this if you need high flow with outdoor placement and have the required venting. A limitation is that outdoor units can be affected by extreme weather unless properly protected.
Rheem RTG Series 7.0 GPM LPG Outdoor
Best for LP fuel setups and outdoor locations where propane is the preferred energy source. It mirrors the natural gas outdoor model in flow and efficiency while offering LP compatibility. This makes it a strong option for homes without a natural gas line. Limitations include outdoor exposure and the need for proper ventilation and weather protection, as with other outdoor units. Best for households needing outdoor LP flexibility.
MIZUDO 120,000 BTU Natural Gas Tankless
Best for flexible installation and smart control. Mizudo offers indoor-outdoor convertible installation with accessory kits, enabling space optimization. It features WiFi/app control and precise temperature stability within 1°F, useful for homes needing centralized control and remote monitoring. It supports multiple outlets and uses gas modulation to maintain consistent temperatures during multi-fixture use. A caution is that the conversion kit and app access require additional setup and accessories, which could add cost and complexity. Choose this for flexibility and advanced control at home.
Rheem RTG Series 7.0 GPM Indoor LP
Best for indoor installations needing space efficiency and direct venting. This unit provides 7.0 GPM at a 35°F rise with 160,000 BTU/hr, matching other high-performance models for multi-point use. Its indoor mounting and direct vent system help integrate into finished spaces with proper ventilation. A limitation is that indoor installation requires venting and proximity to gas lines, which may constrain placement. Choose this if indoor space savings and centralized control are priorities.
Buying Guide: Key Considerations for Non-Condensing Tankless Water Heaters
- Fuel type: Natural gas vs propane. Ensure your home has appropriate gas lines and supply capacity to support the unit’s BTU ratings.
- Installation location: Outdoor units need weather protection and venting; indoor units require proper ventilation and a venting pathway.
- Flow rate needs: Calculate the gallons per minute (GPM) you require for simultaneous fixtures. Larger households benefit from higher GPM models (around 7.0 GPM).
- Temperature rise: Determine the expected temperature increase from the incoming cold water to the desired output. Higher climbs require more BTU and can limit simultaneous usage.
- Space and venting: Consider wall space, mounting options, and whether you need direct-vent exhausts for indoor units.
- Controls and monitoring: Features like LED displays, WiFi/app control, and service alerts help maintenance and efficiency.
- Durability and warranties: Look for comprehensive guarantees on heat exchangers, labor, and parts, and confirm local service availability.
Frequently Asked Questions
- What is a non-condensing tankless water heater? A water heater that heats water on demand without recirculating condensate back to the unit, typically simpler and often less expensive than condensing models.
- Do I need outdoor or indoor installation? Outdoor units avoid venting into living spaces but require weather protection; indoor units need proper ventilation and a vented exhaust system.
- How many fixtures can these units support? Most high-output models handle 2–3 simultaneous showers; exact capacity depends on water temperature rise and fixture demand.
- Is venting required for all indoor models? Yes, indoor units typically require a direct vent system to expel exhaust safely.
- What should I consider for maintenance? LED indicators, service reminders, and accessible service panels help with routine maintenance and fault detection.
- Are there any safety or efficiency concerns? Non-condensing units are generally efficient for their class, but consider climate, venting, and gas line capacity to prevent performance issues.