Tankless water heaters are rapidly becoming the preferred choice for modern homes. Your clients are likely asking about them more often, looking to save space and cut down on energy bills. As a plumbing professional, you need to know exactly which units to recommend to keep your projects running smoothly and your customers happy.
You might be asking yourself: What is the best residential tankless water heater? Answering that question requires looking at a few different variables. Every home has unique needs, and every client has a specific budget. Matching the right unit to the right household is a skill that sets top-tier plumbers apart.
This post will explore the key factors you need to consider when sizing and selecting these units. We will also review the top brands in the industry to help you confidently choose the best residential tankless water heater for your next installation.
Understanding Tankless Water Heaters
How they work: On-demand heating
Traditional tank heaters keep 40 to 50 gallons of water hot 24/7. Tankless units take a completely different approach. They heat water on demand as it flows through the device. When a customer turns on the hot water tap, cold water travels through a pipe into the unit, where a gas burner or an electric element heats it instantly.
Advantages: Energy efficiency, endless hot water, space-saving
Homeowners love the idea of endless hot water. Because tankless models heat water as it is needed, families never have to worry about the last person in the shower getting stuck with cold water. These units also save a significant amount of physical space and use less energy, which translates to lower utility bills over time.
Disadvantages: Upfront cost, flow rate limitations
While the long-term savings are great, the initial purchase and installation costs are higher than standard tanks. Additionally, tankless water heaters have flow rate limits. If a large family tries to run the dishwasher, washing machine, and two showers simultaneously, a single tankless unit might struggle to keep up.
Key Factors in Choosing the Best Residential Tankless Water Heater
GPM (Gallons Per Minute) Requirements
Sizing the unit correctly is the most important step for a successful installation. You need to calculate the total GPM your client requires during peak usage. Think about their daily habits. How many showers might run at the same time? Do they frequently use hot water appliances concurrently? Adding up the flow rates of these fixtures will give you the target GPM.
Fuel Type: Electric vs. Gas (Natural Gas/Propane)
Gas tankless heaters typically offer higher flow rates than electric models, making them ideal for larger homes. However, gas units require proper ventilation and a gas line capable of handling the load. Electric models are easier to install and do not require venting, but they may need significant electrical panel upgrades to handle the high amperage.
Energy Efficiency: EF (Energy Factor) Rating
The Energy Factor (EF) or Uniform Energy Factor (UEF) tells you how efficiently a water heater converts energy into heat. Higher ratings mean better efficiency. Condensing gas models capture exhaust gases to pre-heat incoming cold water, pushing efficiency ratings up to 0.96 UEF. Explaining these long-term savings is a great way to help clients justify the upfront cost.
Venting Requirements (for gas models)
Gas units must be vented to the outside. You will need to choose between direct vent, power vent, or atmospheric vent systems depending on the model and the home’s layout. Venting adds complexity and cost to the job, so you must factor this into your initial estimates.
Installation Costs
The price tag on the unit is only one part of the equation. As a professional, you know that retrofitting a tankless heater into a home designed for a standard tank requires extra work. Gas line upgrades, electrical modifications, and complex venting all impact the total installed cost.
Top Brands for the Best Residential Tankless Water Heater
When your clients ask, “What is the best residential tankless water heater?”, you can point them toward these trusted manufacturers. We only carry reliable, high-quality brands that make your job easier.
Navien
Navien is a major player in the high-efficiency condensing gas market. Their NPE series is famous for its advanced condensing technology, which delivers excellent energy savings and a UEF of up to 0.96. They feature durable stainless steel heat exchangers and offer easy Wi-Fi connectivity. Navien units are a fantastic choice for homes with high hot water demands.
Trutankless
If you are looking at electric options, Trutankless is a highly innovative brand. Their GEN3 electric tankless water heaters are incredibly efficient, using power only when hot water is requested. These units feature smart technology and robust heating elements that activate instantly. They are a great fit for clients who want a high-tech, eco-friendly electric solution without the need for gas lines.
State Water Heaters
State Water Heaters has a long legacy of reliability. Their ProLine XE series features condensing gas tankless units that deliver an endless supply of hot water. For example, their 160,000 BTU models are highly energy efficient and designed for easy indoor installation. Plumbers appreciate State models because they are straightforward to install and built to last.
Stiebel Eltron
Stiebel Eltron is a world leader in electric tankless technology. Their Tempra series is known for proven reliability, sleek space-saving designs, and completely silent operation. Because they do not require venting, Stiebel Eltron units are perfect for tight spaces or point-of-use applications where gas is not an option.
RUUD
RUUD offers a broad range of high-efficiency tankless water heaters. Many of their residential models boast a 0.82 UEF and include built-in EcoNet Wi-Fi technology. RUUD also features exclusive Hot-Start Programming, which minimizes cold water bursts. They are a solid, dependable choice that many plumbing professionals trust for residential installations.
Installation and Maintenance Tips
Professional installation is non-negotiable for tankless units. Proper gas line sizing, correct venting, and safe electrical wiring require an expert touch.
Once installed, regular maintenance keeps these units running efficiently. You should educate your clients on the importance of annual flushing and descaling, especially in areas with hard water. Mineral buildup can severely restrict flow and damage the heat exchanger. Remind them to call you if they notice warning signs like fluctuating water temperatures or reduced water pressure.
Debunking Common Myths about Tankless Water Heaters
Myth 1: They don’t provide truly endless hot water
As long as the unit is sized correctly for the home’s GPM demand, a tankless heater will provide a continuous flow of hot water. The water will not run cold as long as the demand stays within the unit’s capacity.
Myth 2: They are always more expensive
The upfront cost is higher, but the operational costs are much lower. Over the lifespan of the unit, the energy savings often offset the initial investment, making them highly cost-effective in the long run.
Myth 3: They are difficult to maintain
Tankless water heaters actually require less daily maintenance than standard tanks. An annual flush with a vinegar solution is usually all it takes to keep the system in perfect working order.
Make Your Next Plumbing Project a Breeze
Choosing the “best” tankless water heater always comes down to the specific needs of the property and the preferences of the homeowner. By understanding GPM requirements, fuel types, and the strengths of leading brands like Navien, Trutankless, State Water Heaters, Stiebel Eltron, and RUUD, you can provide expert recommendations that build trust with your clients.
When you are ready to secure the supplies for your next installation, Van Marcke Plumbing Supply is your go-to partner. We carry an extensive product range of over 6,000 brand-name products across our locations in Arizona, Nevada, and Texas. With our intuitive e-commerce platform, PlumbersOnly.com, you can shop anytime, anywhere. Plus, our loyalty rewards program ensures you get something back for your continuous support. Log in today to check our competitive pricing and secure the inventory you need to get the job done right.
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The Best Residential Tankless Water Heaters for Plumbers
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What is the best residential tankless water heater? Discover top brands like Navien and RUUD, plus sizing tips to help you tackle your next plumbing project.