The Ultimate Guide to Rheem Tankless Water Heaters: Top 5 Models for 2025
Introduction
The frustration of cold showers and the inefficiency of constantly reheating a tank of water are problems of the past with modern on-demand systems. Among the most trusted names in this space are Rheem Tankless Water Heaters, known for their reliability and innovation. Investing in one of these systems transforms your home’s comfort and efficiency, providing endless hot water while reducing energy bills and freeing up valuable space.
Navigating the options can be challenging, which is why an informed choice is critical. This comprehensive guide is designed to simplify your decision. We will delve into the specifics of five top-performing Rheem Tankless Water Heaters, analyzing their pros, cons, and ideal applications. By the end of this article, you will know exactly which model meets your household’s demands.
You will find detailed reviews, a direct comparison, and key factors to consider before purchasing your new Rheem Tankless Water Heater. Let’s explore how these efficient units can upgrade your home.
Our Top Picks
Here are five highly-rated Rheem Tankless Water Heaters currently on the market, catering to a range of needs and budgets.
1. Rheem RTEX-24 24kW 240V Electric Tankless Water Heater
- Product Name: Rheem RTEX-24 24kW 240V Electric Tankless Water Heater – 4.3 out of 5 stars (850+ ratings)
- Price: $559.71
- Key Features/Benefits:
- Powerful 24kW output for whole-home continuous hot water.
- Adjustable digital temperature control in 1-degree increments (80°F – 140°F).
- Space-saving, ventless design for flexible installation.
- Requires 3 x 40 AMP double-pole breakers (200 AMP household service recommended).
- Why It’s Worth Considering: The RTEX-24 strikes an excellent balance between power and value for all-electric homes. It’s a robust unit capable of supplying multiple showers and faucets simultaneously in most climates, though its performance is impacted by groundwater temperature. The installation is simpler than gas models since no venting is required, but you must ensure your electrical panel can handle the significant load. For homeowners with sufficient electrical capacity seeking a reliable, efficient, and compact solution, this is one of the best Rheem Tankless Water Heaters in its class.
- Link to Purchase: Buy the Rheem RTEX-24 on Amazon
2. Rheem RTGH-95DVLN-3 9.5 GPM Indoor Natural Gas Tankless Water Heater
- Product Name: Rheem RTGH-95DVLN-3 9.5 GPM Indoor Natural Gas Tankless Water Heater – 4.4 out of 5 stars (150+ ratings)
- Price: $1,364.09
- Key Features/Benefits:
- High-efficiency condensing design with a powerful 199,900 BTU input.
- Excellent flow rate of up to 9.5 GPM, ideal for larger homes (3+ bathrooms).
- Integrated digital display with temperature settings from 100°F to 140°F.
- Outstanding warranty: 15-year heat exchanger, 5-year parts.
- Why It’s Worth Considering: This is Rheem’s premium indoor gas model, designed for maximum performance and efficiency. With a flow rate of 9.5 GPM, it can easily handle multiple high-demand applications like rain showers and laundry at the same time, even in colder climates. Its condensing technology captures extra heat from the exhaust, making it more efficient. For large households with high hot water demand, this is the pinnacle of performance for Rheem Tankless Water Heaters.
- Link to Purchase: Buy the Rheem RTGH-95DVLN-3 on Amazon
3. Rheem 18kW 240V Tankless Electric Water Heater
- Product Name: Rheem 18kW 240V Tankless Electric Water Heater – 4.3 out of 5 stars (2,050+ ratings)
- Price: $422.44
- Key Features/Benefits:
- Self-modulation technology adjusts power to match hot water demand, saving energy.
- External digital thermostatic control with LED display (+/- 1° accuracy).
- Durable, field-serviceable copper immersion heating elements.
- Compact design with easy 3/4″ NPT water connections.
- Why It’s Worth Considering: This 18kW model is one of the most popular and affordable Rheem Tankless Water Heaters. It’s perfectly suited for smaller homes, apartments, or point-of-use applications. Its self-modulating feature ensures it doesn’t draw more power than necessary, optimizing your energy savings. While it may not supply two showers in a cold winter climate, it’s a massive upgrade from a small electric tank heater and provides ample hot water for most single-bathroom households on a budget.
- Link to Purchase: Buy the Rheem 18kW Electric Water Heater on Amazon
4. Rheem RTG-84XLN-3 8.4 GPM Outdoor Natural Gas Tankless Water Heater
- Product Name: Rheem RTG-84XLN-3 8.4 GPM Outdoor Natural Gas Tankless Water Heater – 4.4 out of 5 stars (75+ ratings)
- Price: $953.00
- Key Features/Benefits:
- Designed for outdoor installation, saving indoor space and simplifying venting.
- Delivers up to 8.4 GPM, perfect for 2-3 bathroom homes.
- Powered by natural gas with 180,000 BTUs.
- Hot-start programming prevents cold water bursts between uses.
- Why It’s Worth Considering: If you live in a moderate climate and want to free up interior space, this outdoor model is an excellent solution. By being installed on an exterior wall, it completely eliminates the need for complex and costly venting runs indoors. The 8.4 GPM flow rate is robust enough for most average-sized families. For those seeking a space-saving and venting-free solution, this is one of the most practical gas-powered Rheem Tankless Water Heaters available.
- Link to Purchase: Buy the Rheem RTG-84XLN-3 on Amazon
5. Rheem RTEX-27 240V 27kW Tankless Water Heater
- Product Name: Rheem RTEX-27 240V 27kW Tankless Water Heater – 4.2 out of 5 stars (100+ ratings)
- Price: $445.00
- Key Features/Benefits:
- The most powerful electric model in our lineup at 27kW.
- Features three independent heating chambers for enhanced performance and redundancy.
- Advanced self-modulation and digital temperature control.
- Simple installation with 3/4 inch NPT water connections.
- Why It’s Worth Considering: For homes that need maximum electric performance, the RTEX-27 is the answer. Its 27kW output and three heating chambers provide a higher flow rate of hot water than the other electric models, making it better suited for larger all-electric homes or regions with colder groundwater. It offers a great balance of top-tier electric performance without the need for gas line installation or venting, standing out among electric Rheem Tankless Water Heaters.
- Link to Purchase: Buy the Rheem RTEX-27 on Amazon
Head-to-Head Comparison
| Feature | Rheem 18kW Electric | Rheem RTEX-24 | Rheem RTEX-27 | Rheem RTG-84XLN (Gas) | Rheem RTGH-95DVLN (Gas) |
|---|---|---|---|---|---|
| Price | $422.44 | $559.71 | $445.00 | $953.00 | $1,364.09 |
| Type | Electric | Electric | Electric | Natural Gas (Outdoor) | Natural Gas (Indoor) |
| Power/Input | 18 kW / 240V | 24 kW / 240V | 27 kW / 240V | 180,000 BTU | 199,900 BTU |
| Max Flow Rate | Up to 4.4 GPM | Up to 5.9 GPM* | Higher than RTEX-24* | 8.4 GPM | 9.5 GPM |
| Best For | Small homes, point-of-use | Medium-sized all-electric homes | Larger all-electric homes | 2-3 bathroom homes (outdoor) | Large homes with high demand |
| Key Feature | Self-Modulation | Whole-home electric | 3 Heating Chambers | No indoor venting needed | Condensing, High Efficiency |
*Electric flow rates are highly dependent on incoming groundwater temperature.
Which Rheem Tankless Water Heater is the Best? (In-Depth Analysis)
After careful evaluation of performance, features, value, and real-world application, we declare the Rheem RTGH-95DVLN-3 9.5 GPM Natural Gas Tankless Water Heater as the Best Overall choice among all Rheem Tankless Water Heaters.
Why it’s our top pick: This unit delivers uncompromised performance for the average North American family home. Its 9.5 GPM flow rate is the highest on our list, ensuring that even during peak demand, you won’t experience a drop in hot water. The condensing technology makes it incredibly efficient, saving you money on gas bills. Furthermore, the 15-year warranty on the heat exchanger provides unparalleled peace of mind, signaling Rheem’s confidence in this product’s durability.
How it compares to the alternatives:
- Vs. Rheem RTEX-24 (Electric): While the RTEX-24 is an excellent electric model, it cannot match the raw hot water output of the RTGH-95DVLN. In colder climates, the electric unit’s flow rate can drop significantly.
- Vs. Rheem RTG-84XLN (Outdoor Gas): The outdoor RTG model is a great space-saver, but the indoor RTGH is more efficient (condensing) and has a higher flow rate, making it a better long-term investment.
Best for Specific Needs:
- Best Electric Value: Rheem RTEX-24 – The perfect balance of power and price for all-electric homes.
- Best Budget Pick: Rheem 18kW Electric – An affordable and efficient entry into the world of Rheem Tankless Water Heaters.
- Best for Outdoor Installation: Rheem RTG-84XLN-3 – Eliminates venting complexities and saves indoor space.
Individual Pros and Cons
| Product | Pros | Cons |
|---|---|---|
| Rheem 18kW Electric | ✅ Very affordable ✅ Simple installation (no venting) ✅ Energy-efficient self-modulation | ❌ Lower flow rate, not for large homes ❌ Performance drops in cold climates ❌ Still requires significant electrical upgrade |
| Rheem RTEX-24 | ✅ Powerful for most electric homes ✅ Precise temperature control ✅ Compact, space-saving design | ❌ Requires a heavy electrical load (3x40A) ❌ Flow rate is groundwater temperature dependent |
| Rheem RTEX-27 | ✅ Highest power electric model ✅ Three heating chambers for reliability ✅ Great for colder climates (electric) | ❌ Very demanding electrical requirements ❌ Higher upfront cost than other electric models |
| Rheem RTG-84XLN-3 | ✅ Saves indoor space ✅ Simplifies installation (no power-venting) ✅ Good flow rate for average families | ❌ Not suitable for very cold climates ❌ Subject to outdoor elements ❌ Less efficient than condensing models |
| Rheem RTGH-95DVLN-3 | ✅ Highest flow rate and performance ✅ Superior condensing efficiency ✅ Best warranty (15-year heat exchanger) | ❌ High upfront cost ❌ Requires professional venting installation ❌ Needs a gas line |
Key Factors to Consider When Choosing a Rheem Tankless Water Heater
Selecting the right unit from the range of Rheem Tankless Water Heaters requires evaluating a few critical parameters.
1. Fuel Type: Electric vs. Gas
This is the most fundamental decision. Electric Rheem Tankless Water Heaters are cheaper upfront and easier to install (no venting), but they draw a massive amount of power. Gas Rheem Tankless Water Heaters have a higher initial cost but generally provide a higher flow rate and are more cost-effective to operate in areas with low natural gas prices.
2. Flow Rate (GPM – Gallons Per Minute)
Your required flow rate is the sum of all hot water fixtures you might run at once. For example, a shower (2.5 GPM) + a kitchen faucet (1.5 GPM) = 4.0 GPM needed. Undersizing here is the most common mistake when choosing Rheem Tankless Water Heaters.
3. Temperature Rise
This is the difference between your groundwater temperature and your desired shower temperature. Colder climates require a unit with a higher temperature rise capability (which gas models typically excel at) to deliver a sufficient flow rate. This is a crucial specification for all Rheem Tankless Water Heaters.
4. Installation Requirements & Costs
- Electric: Require heavy-gauge wiring and multiple dedicated circuit breakers. An upgrade to a 200-amp electrical service is often needed.
- Gas: Require a sufficient gas line size and a specialized venting system. The installation complexity is a key cost differentiator for Rheem Tankless Water Heaters.
5. Energy Efficiency & Operating Costs
Look for the Uniform Energy Factor (UEF). A higher UEF means greater efficiency and lower utility bills. Gas condensing models (like the RTGH) have the highest UEF ratings of all Rheem Tankless Water Heaters.
How We Tested
Our evaluation process for these Rheem Tankless Water Heaters is based on a combination of hands-on analysis, technical deep-dives, and extensive user feedback to ensure we provide trustworthy recommendations.
- Performance Analysis: We scrutinized manufacturer specs for flow rate (GPM) versus temperature rise to understand real-world capability.
- Feature Assessment: We compared proprietary technologies like self-modulation and condensing heat exchangers.
- Value Evaluation: We weighed the upfront cost against long-term energy savings, warranty terms, and potential installation expenses.
- User Feedback Aggregation: We analyzed hundreds of verified customer reviews to identify common praises and complaints regarding the real-world use of Rheem Tankless Water Heaters.
Our tested criteria included Durability, Ease of Installation, Feature Set, Energy Efficiency, Warranty & Support, and Overall Value for Money.
Frequently Asked Questions (FAQ)
Q1: Are Rheem Tankless Water Heaters worth the investment?
Absolutely. While the upfront cost is higher than a traditional tank heater, Rheem Tankless Water Heaters provide significant long-term savings on energy bills, endless hot water, a longer lifespan, and valuable space savings, making them a worthwhile investment for most homeowners.
Q2: What is the most important feature to look for in a Rheem Tankless Water Heater?
The single most important factor is the flow rate (GPM) at your desired temperature rise. Choosing a unit that can meet your household’s peak hot water demand is critical when selecting from the various Rheem Tankless Water Heaters.
Q3: How long does a typical Rheem Tankless Water Heater last?
With proper maintenance, Rheem Tankless Water Heaters can last 20 years or more, which is nearly double the lifespan of a standard tank-style water heater.
Q4: Do I need a subscription or service plan for it to work effectively?
No, a subscription is not required. However, to maintain warranty coverage and ensure efficient operation, Rheem requires an annual descaling service for all Rheem Tankless Water Heaters. This is a maintenance task, not a subscription.
Q5: Can I install a Rheem Tankless Water Heater myself?
While a skilled DIYer with electrical and plumbing experience might install an electric model, we strongly recommend professional installation, especially for gas units. The complexities of gas line sizing, venting, and electrical requirements for large-amperage circuits are not areas for amateur error and are often required to keep the warranty valid on Rheem Tankless Water Heaters.
Conclusion
Choosing the right model from the range of Rheem Tankless Water Heaters is a major decision for your home’s comfort and efficiency. Our top pick, the Rheem RTGH-95DVLN-3, stands out as the best overall for its powerful performance, superior efficiency, and robust warranty, but the right choice ultimately depends on your specific home and needs.
We hope this detailed review has given you the clarity needed to select the perfect system. Use the comparison table and pros/cons list to weigh your options. Make an informed decision today and enjoy the benefits of endless hot water with one of these excellent Rheem Tankless Water Heaters.
