For whole-home gas hot water, a condensing model is generally the better fit when efficiency is a priority and the installation can accommodate its venting and condensate requirements; a non-condensing model may suit buyers seeking a simpler tankless configuration. Among these options, the Rinnai RX160iN is best for efficient residential use, the Rheem RTG is best for a non-condensing setup, and the Rinnai CX199iN is aimed at higher-demand or commercial applications. The Westinghouse listing has conflicting installation descriptions, so verify the exact model requirements before buying.
| Product | Type | Best suited for |
|---|---|---|
| Rheem RTG Series 7.0 GPM | Non-condensing, natural gas | Homes comparing non-condensing whole-house options |
| Rinnai RX160iN | Condensing, propane or natural gas | Efficiency-focused homes with multiple hot-water fixtures |
| Westinghouse 7.9 GPM | Propane tankless; installation details conflict | Buyers who confirm installation and fuel requirements |
| Rinnai CX199iN | Condensing, commercial-oriented | High-demand applications requiring greater stated flow |
| Immersion Water Heater | Portable electric immersion heater | Small-volume water heating, not whole-home service |
Rheem RTG Series 7.0 GPM Non-Condensing
This is a non-condensing, natural-gas tankless water heater intended for indoor installation. Its listed output is 160,000 BTU per hour, with a stated 7.0 gallons per minute (GPM) at a 35°F temperature rise. The product description says it can support two to three simultaneous showers or water points, depending on demand and conditions.
Best for: Buyers who specifically want a non-condensing whole-house tankless unit and have natural gas service. The wall-mounted design is also relevant where reclaiming floor space matters. It was selected because it provides a direct comparison point against the condensing models in this list.
- Listed Uniform Energy Factor (UEF): 0.82.
- Indoor installation with a direct-vent system.
- Designed as a replacement option for an aging tank heater.
Limitation: Its stated flow is lower than the Rinnai RX160iN and CX199iN figures. Confirm whether the output meets the home’s peak simultaneous demand, and check the required venting and gas supply with a qualified installer.
Rinnai RX160iN Condensing Tankless Heater
The Rinnai RX160iN is a condensing tankless model listed for propane or natural gas. Its Smart Sense gas control system is described as supporting either fuel, while its Versa Vent design allows indoor or outdoor installation according to the product information. Outdoor installation requires the RX-OVC vent cap.
Best for: Households seeking a high-efficiency condensing model for several hot-water fixtures. The product lists up to 9 GPM, capacity for six fixtures at once, and a UEF of 0.97. Those figures make it a stronger stated-flow and efficiency option than the Rheem, although actual performance depends on incoming water temperature, flow demand, and installation.
- Compact, described as about the size of a small suitcase.
- Includes a Quick Flush feature and an easy-to-use interface.
- Wi-Fi control requires a Controlr module, which is not included.
Limitation: Buyers need to account for the additional outdoor vent cap if using that installation method. Confirm local installation requirements and condensate handling for a condensing unit before choosing it.
Westinghouse 7.9 GPM Propane Tankless Heater
This Westinghouse listing describes a propane tankless heater with 180,000 BTU output and up to 7.9 GPM. It also lists app and voice control, operating-status monitoring, fault alerts, and temperature stability within ±1°F through self-modulating technology.
Best for: Buyers considering a propane model who value the listed remote-control features and want a stated capacity between the Rheem’s 7.0 GPM and the Rinnai RX160iN’s 9 GPM. The product description says it can support three to five fixtures simultaneously, but fixture count is not a substitute for checking actual flow and temperature-rise needs.
- App-based temperature adjustment and operating-status monitoring are listed as standard features.
- Voice control is also listed, without requiring extra accessories according to the description.
- Stated output is 180,000 BTU.
Limitation: The provided product title says “Indoor,” while its feature text says “Designed for outdoor installation” and calls it an indoor heater elsewhere. These descriptions conflict. Verify the exact model’s approved location, venting, and installation instructions before purchase.
Rinnai CX199iN High-Output Condensing Heater
The Rinnai CX199iN is described as a commercial tankless water heater with a 199,000 BTU rating. Its listing gives a maximum output of 11.1 GPM, capacity for up to seven fixtures at once, and a UEF of 0.98. It is a condensing model designed for propane or natural gas, with indoor or outdoor installation described through the Versa Vent system.
Best for: Buyers with unusually high hot-water demand or a commercial application who need a higher stated flow than the residential-focused models here. Its higher listed capacity is the main reason to consider it over the RX160iN; a larger unit is not automatically the right choice for an average home.
- Smart Sense gas control is listed for propane or natural gas.
- Quick Flush feature and an easy-to-use interface are included in the description.
- Outdoor installation requires an RX-OVC vent cap.
Limitation: The listing identifies this as a commercial model. Confirm that its capacity, fuel supply, installation requirements, and intended application fit the project. Wi-Fi control requires a Controlr module that is not included.
Portable 2000W Immersion Water Heater
This product is not a condensing or non-condensing whole-house water heater. It is a portable electric immersion heater intended for small containers of water, such as buckets, tubs, or small pools. The listing describes a 2,000-watt heating element, a 304 stainless-steel guard, and an LCD thermometer.
Best for: Buyers who need occasional, localized water heating rather than a permanent home hot-water system. It is included to distinguish a portable water-heating tool from the gas tankless units in this comparison.
- Designed for 110–125V AC according to the listing.
- The product description says it can heat up to five gallons in a few minutes; actual time varies with water volume and starting temperature.
- Must be fully immersed before connecting to power, and the listing says to heat water only.
Limitation: It is not a replacement for a whole-home water heater and does not provide continuous plumbing hot water. Follow the operating instructions carefully, especially the immersion requirement.
Buying Guide: Condensing vs. Non-Condensing Water Heaters
What is the difference between condensing and non-condensing?
Both types burn gas to heat water. A condensing unit captures additional heat from exhaust gases and uses it to help heat incoming water. Because it extracts more heat before exhaust leaves the appliance, it generally needs a condensate drain and materials designed to handle cooler, acidic condensate. Installation details vary by model.
A non-condensing tankless heater sends hotter exhaust through its venting system and typically does not use the same condensate-drain arrangement. Its vent materials and clearances must match the manufacturer’s instructions. “Simpler” does not mean that venting is optional or that every existing vent can be reused.
Which type is more efficient?
Condensing models often have higher efficiency figures because they recover more heat from combustion. In this selection, the Rinnai RX160iN lists a UEF of 0.97 and the CX199iN lists 0.98, while the Rheem non-condensing model lists 0.82. Compare models using the same efficiency metric and check the exact model documentation; efficiency figures alone do not determine total operating cost.
Actual energy use also depends on household hot-water habits, incoming water temperature, fuel cost, sizing, and installation. Avoid treating a product’s stated potential savings as a guaranteed result for every home.
How should you compare flow rate and capacity?
GPM describes water flow under a specified condition. The Rheem’s listed rating is 7.0 GPM at a 35°F temperature rise, while the other listings give maximum GPM figures without the same condition in the supplied features. These numbers may not be directly comparable. Ask an installer to calculate the required temperature rise for the home’s climate and expected simultaneous use.
Make a list of fixtures likely to operate at once, such as showers, sinks, a dishwasher, or laundry equipment. A claim such as “six fixtures” is a product-description estimate, not a guarantee for every combination of fixtures or water temperatures.
What fuel and installation details should you check?
- Fuel: Confirm whether the unit is designed for natural gas, propane, or both. Do not assume a model can switch fuels unless the manufacturer specifies it.
- Location: Verify whether the model is approved for indoor, outdoor, or either type of installation.
- Venting: Check vent type, route, clearances, and any required accessories. The RX160iN and CX199iN listings specify an RX-OVC vent cap for outdoor installation.
- Condensate: For condensing equipment, establish how condensate will be drained and handled according to the installation instructions and local code.
- Utilities: Have a qualified professional confirm gas supply, electrical needs, water connections, and applicable permits.
When is non-condensing the better comparison?
Consider a non-condensing model when its stated output meets the household’s demand and its installation requirements suit the home. It may be a useful option for buyers comparing a conventional tankless arrangement with condensing equipment. The Rheem in this list is the only clearly identified non-condensing whole-house unit, so compare it with other models of similar capacity rather than judging by price or efficiency alone.
When should you choose a condensing model?
A condensing model is worth considering when higher efficiency is a priority and the home can accommodate the required venting and condensate arrangements. The RX160iN is the more residential-oriented choice among the listed condensing options based on its stated 9 GPM output. The CX199iN lists higher output and a commercial designation, making it more appropriate to evaluate for larger or higher-demand applications.
Is a tankless heater the right type of replacement?
Tankless heaters save storage space and heat water on demand, but a replacement is not always a simple swap. Existing gas capacity, venting, electrical service, water conditions, and household demand can affect installation. Compare a tankless unit with a suitably sized storage-tank heater if upfront installation complexity, peak demand, or the home’s infrastructure is a concern.
Frequently Asked Questions
Is a condensing water heater always the better choice?
No. Condensing models often offer higher efficiency, but their installation requirements and the home’s hot-water needs also matter. Compare total project requirements, capacity, and efficiency rather than selecting by type alone.
Does a higher GPM rating mean a heater will serve more fixtures?
Not necessarily. Flow depends on temperature rise and the combined demand of fixtures. Check the manufacturer’s performance data for the expected incoming water temperature and have the household’s peak use assessed.
Can a condensing tankless heater be installed outdoors?
Some models allow outdoor installation, but requirements are model-specific. The Rinnai listings specify an RX-OVC vent cap for outdoor installation. Follow the exact instructions and local requirements.
Does the Westinghouse listing confirm indoor or outdoor use?
No. The supplied title says “Indoor,” while the feature text describes outdoor installation and also uses “indoor.” Confirm the exact model’s installation rating and instructions before purchasing.
Can the portable immersion heater replace a home water heater?
No. It is designed to heat small amounts of water in a container, not to supply a home’s plumbing fixtures. Use a properly sized whole-house water heater for household hot-water service.