Introduction
Upgrading to a tankless water heater is one of the smartest home improvement decisions you can make — but choosing the wrong unit can lead to lukewarm showers, wasted money, and ongoing frustration. With dozens of models across multiple fuel types and capacity ranges, the selection process can feel overwhelming.
The good news: it doesn’t have to be. In this guide, our licensed tankless water heater installation specialists walk you through every factor you need to consider so you can confidently choose the right unit for your home, your family, and your budget.
Step 1: Determine Your Fuel Type — Gas or Electric?
The first decision is your fuel source. Tankless water heaters are available in both natural gas/propane and electric models, and the best choice depends on your home’s existing infrastructure.
Gas Tankless Water Heaters:
- Higher flow rates — better suited for larger households with multiple simultaneous hot water demands
- Generally more energy-efficient for high-usage homes
- Require existing gas lines and adequate venting
- Higher upfront cost, but often lower operating cost long-term
Electric Tankless Water Heaters:
- Easier to install in homes without existing gas infrastructure
- No venting required — more flexible placement
- Better suited for smaller households or point-of-use applications
- May require electrical panel upgrades for whole-home units
Pro Tip: If your home already has natural gas service and you have a larger household, a gas unit is typically the stronger long-term investment.
Step 2: Calculate Your Required Flow Rate (GPM)
Flow rate — measured in gallons per minute (GPM) — is one of the most critical specs when sizing a tankless water heater. It determines how many hot water outlets your unit can serve simultaneously.
To calculate your required flow rate, add up the GPM of every fixture you might use at the same time:
- Shower: 1.5–2.5 GPM
- Kitchen faucet: 1.0–1.5 GPM
- Dishwasher: 1.0–1.5 GPM
- Washing machine: 1.5–2.0 GPM
- Bathroom faucet: 0.5–1.0 GPM
For a household running two showers and a kitchen faucet simultaneously, you’d need a unit capable of at least 5–7 GPM. Always size up slightly to account for peak demand and temperature rise requirements.
Step 3: Account for Temperature Rise
Temperature rise is the difference between incoming groundwater temperature and your desired output temperature (typically 120°F). In colder climates where groundwater enters at 40–50°F, you need a greater temperature rise — which requires a more powerful unit.
Your licensed installer will factor your local groundwater temperature into the sizing calculation to ensure your unit delivers consistent hot water year-round.
Step 4: Choose Between Whole-Home vs. Point-of-Use Units
Whole-Home Tankless Water Heaters:
These high-capacity units supply hot water to every fixture in your home from a single installation point. They’re the most popular choice for homeowners upgrading from a traditional tank system.
Point-of-Use Tankless Water Heaters:
Smaller, compact units installed close to a specific fixture (a bathroom, kitchen sink, or garage utility sink). They eliminate hot water wait time and reduce pipe heat loss for that specific application. Often used to supplement a whole-home system.
Step 5: Consider These Additional Factors
- Energy Factor (EF) / Uniform Energy Factor (UEF): Higher ratings mean greater efficiency. Look for ENERGY STAR certified models for maximum savings.
- Condensing vs. Non-Condensing: Condensing models capture heat from exhaust gases for additional efficiency — ideal for colder climates and high-demand households.
- Venting Requirements: Gas units require either direct vent, power vent, or concentric vent systems. Your installer will assess your home and recommend the correct configuration.
- Hard Water Compatibility: In areas with hard water, consider units with built-in scale protection or plan for a water softener to protect the heat exchanger.
- Warranty: Look for units with strong heat exchanger warranties (10–15 years) and comprehensive parts coverage.
Top Brands We Install and Service
Our technicians are trained and experienced with all major tankless water heater brands, including:
- Rinnai — Industry leader in gas tankless systems with excellent reliability
- Navien — Known for condensing technology and built-in recirculation
- Noritz — Strong performance with excellent warranty coverage
- Rheem — Widely available with solid electric and gas options
- Bosch — Excellent for point-of-use and smaller household applications
- Bradford White — Commercial-grade reliability for demanding applications
Let Us Handle the Sizing and Selection
Choosing the right tankless water heater involves more variables than any online calculator can fully account for. Our licensed technicians will assess your home’s hot water usage patterns, fuel source, water hardness, and budget to recommend the optimal unit — then install it correctly, to code, the first time.
Call 909-925-2665 or book a consultation online today. Professional tankless water heater installation with upfront pricing, guaranteed satisfaction.
