Answer: Condensing models maximize energy savings by capturing and reusing waste heat, while non-condensing units offer straightforward, reliable hot water on demand. This guide compares five popular options to help buyers choose the right fit for household size and installation setup. Best for outdoor installations, multi-bath homes, and energy-savvy households are highlighted. The following table summarizes the key distinctions and target use cases for each product.
| Product | Condensing? | Best For |
|---|---|---|
| Rheem RTG Series 7.0 GPM Liquid Propane (Outdoor) | No | Outdoor living spaces; mid-size homes with propane supply |
| Rheem RTG Series 8.4 GPM Natural Gas (Indoor) | No | Indoor installation; larger households needing multiple fixtures |
| ThermoMate Condensing Tankless (Natural Gas) | Yes | Homes prioritizing energy efficiency; multi-point heating |
| Rheem Prestige Condensing Tankless (Indoor, with Recirculation) | Yes | Compact spaces; fast hot water with recirculation |
| Rheem RTG Series 9.5 GPM Natural Gas (Outdoor) | No | Large homes; outdoor setups requiring high flow |
Rheem RTG Series 7.0 GPM Outdoor Propane Tankless
This outdoor, non-condensing propane tankless model provides 7.0 GPM with 160,000 BTU/hr. It is designed for two to three simultaneous showers in typical homes and is ideal for outdoor installation where venting is not required. It emphasizes on-demand hot water with energy-conscious operation.
Best for: homes that favor outdoor installation and propane supply; smaller to mid-size households needing steady hot water for several fixtures. Consideration: outdoor exposure means weather protection and proper mounting by a qualified installer.
Rheem RTG Series 8.4 GPM Indoor Natural Gas
This indoor, non-condensing unit delivers 8.4 GPM and 180,000 BTU/hr, suitable for households needing multiple daily showers. It uses a direct vent system and supports wall mounting for efficient space use. It is a robust choice for upgrades from aging tank heaters.
Best for: larger families in need of reliable hot water with indoor installation. Limitation: venting and indoor space requirements must be evaluated by a professional installer.
ThermoMate Condensing Tankless Gas (5.28 GPM)
This condensing model uses a dual heat exchanger to reclaim heat and achieve up to 0.86 UEF. It offers 5.28 GPM at 114,000 BTU and can supply two showers simultaneously with precise temperature control. The system includes multiple protections for safe operation.
Best for: households aiming to maximize energy efficiency and reduce operating costs; good for two-bath households with moderate hot water demand. Caution: higher upfront cost typical for condensing technology.
Rheem Prestige Condensing Indoor (11.0 GPM)
This indoor condensing model provides 11.0 GPM and focuses on reduced wait time with a built-in recirculation feature. It emphasizes high energy efficiency and compact size, making it suitable for tank replacements in space-constrained homes.
Best for: homes needing fast, plentiful hot water without extensive venting; ideal for compact spaces and multi-point usage. Limitation: condensing systems may require more complex installation and service considerations.
Rheem RTG Series 9.5 GPM Outdoor Non-Condensing
This outdoor, non-condensing unit delivers 9.5 GPM with 199,900 BTU/hr, designed for large households and outdoor installations. It supports multiple fixtures simultaneously and eliminates venting requirements for outdoor setup.
Best for: large homes with extensive hot water needs and outdoor installation; choose this if you require higher flow rates and outdoor placement. Caution: ensure proper weather protection and professional mounting for outdoor hardware.
Buying Guide: Key Considerations for Condensing vs Non-Condensing Tankless Water Heaters
- Energy efficiency and operating costs: Condensing models typically achieve higher efficiency (often 0.86 or similar UEF) by reusing exhaust heat, which can translate to lower energy bills over time.
- Installation environment: Outdoor units avoid venting but require weather protection. Indoor units need proper venting and space planning for optimal performance.
- Flow rate and heating demand: Assess GPM needs based on simultaneous hot water usage (showers, sinks, appliances). Higher GPM models suit larger households or multi-bath homes.
- Vent and recirculation features: Condensing units may benefit from dedicated venting plans; models with built-in recirculation can deliver faster hot water at fixtures but may add complexity.
- Maintenance and durability: Condensing heat exchangers are corrosion-resistant but may require more routine checks. Non-condensing units generally have fewer moving parts but venting considerations can influence long-term upkeep.
- Space and mounting: Wall-mount designs save floor space; ensure mounting surfaces and clearances meet manufacturer guidelines.
- Fuel type and availability: Propane and natural gas options affect installation choices and running costs; confirm local supply and appliance compatibility.
Frequently Asked Questions
- What is the main advantage of a condensing tankless water heater?
Answer: They reclaim heat from exhaust to improve energy efficiency and reduce operating costs over time. - Do I need venting for a non-condensing unit?
Answer: Yes, most non-condensing models require venting to expel combustion gases. - Is indoor installation safer than outdoors for tankless heaters?
Answer: Indoor installations require proper venting and space planning; outdoors avoid venting but need weather protection. - How do I determine the right GPM for my home?
Answer: Estimate simultaneous hot water usage (showers, sinks, appliances) and choose a unit with higher GPM to cover peak demand. - Are recirculation features worth it?
Answer: Recirculation can reduce wait time for hot water but adds system complexity and potential energy considerations. - Can I replace a traditional tank with a condensing tankless heater?
Answer: In many cases yes, but it requires evaluating space, venting, fuel type, and electrical or gas supply compatibility.