As winter approaches, reliable hot water becomes essential for comfort and convenience. Whether you’re replacing an outdated unit or upgrading to an energy-efficient system, tankless water heater installation can be one of the smartest investments for your home.
Unlike traditional tanks that store and constantly reheat water, tankless systems heat water on demand, saving both space and energy. However, proper installation is crucial to ensure safety, efficiency, and compliance with local codes.
In this comprehensive guide, our certified experts at Heatwave Water Heater Service walk you through everything you need to know about installing a tankless water heater — from choosing the right model to performing final tests and safety checks.
Step-by-Step: How to Do Tankless Water Heater Installation
Read on to learn more about the tankless water heater installation with Heatwave Water Heater Service in Phoenix, AZ, and nearby areas:
Step 1: Choose the Right Tankless Water Heater
The first step in tankless water heater installation is to determine which system fits your home’s needs.
- Gas-powered units are best if you already have a natural gas line or propane supply. They heat water quickly and are ideal for larger households.
- Electric models work well for smaller homes or condos and offer quieter, cleaner operation, though they may require an upgraded electrical panel.
When choosing, also consider:
- Flow rate (gallons per minute) based on your household size.
- Energy efficiency rating (EF or UEF) for long-term savings.
- Space and ventilation needs depend on your layout.
| Expert Tip For a family of four, look for a model with at least a 7–8 GPM (gallons per minute) flow rate. |
Step 2: Verify Power, Gas, and Water Requirements
Before tankless water heater installation, confirm that your home can handle the new system’s power needs.
- Gas units: Check the BTUH (British Thermal Unit per Hour) rating. Your existing gas line may need upgrading to accommodate higher flow.
- Electric units: Ensure your breaker panel supports the amperage—often 120–150 amps for large tankless systems.
- Water lines: Verify pipe compatibility and water pressure (ideally between 30–80 PSI).
| Safety Reminder If you’re unsure about gas or electrical compatibility, always consult a licensed professional. |
Step 3: Select the Proper Location
A well-chosen tankless water heater installation spot ensures efficiency and easy maintenance.
- Mount near major water outlets (kitchen or bathroom).
- For gas models, pick a space with proper ventilation or an exterior wall for flue access.
- Maintain at least 24 inches of clearance around the unit.
- Avoid damp basements or uninsulated garages unless protected from freezing.
Step 4: Shut Off Utilities
Before working on the tankless water heater installation system:
- Turn off the main gas valve or electrical supply.
- Shut off the water supply to prevent flooding.
- Drain remaining water from your old tank through a hose connection.
- Flip the circuit breaker to ensure full electrical isolation.
Safety first — this step prevents electrical shocks, leaks, and gas hazards.
Step 5: Drain and Remove the Old Water Heater
Attach a garden hose to the drain valve and empty all the water. To relieve pressure, turn on a hot water faucet nearby. If your unit is in a basement, a portable sump pump can help remove residual water. Once fully drained, disconnect the plumbing and gas lines, then remove the old heater carefully for tankless water heater installation.
| Pro Tip Dispose of the old unit according to local recycling or hazardous-waste regulations. |
Step 6: Mount the Bracket and Install the New Unit
Most tankless water heaters come with wall brackets and mounting templates.
- Use a stud finder to locate solid wall support.
- Drill mounting holes and attach the bracket.
- Hang the unit securely on the wall, ensuring level alignment.
- Leave enough space below for pipe connections and filter access.
Step 7: Connect Water Lines
With tankless water heater installation, make sure to attach the cold water inlet and hot water outlet using flexible stainless-steel pipes. Install:
- Isolation valves for future maintenance.
- Pressure-relief valves for safety.
- Filter screens to prevent debris buildup.
Seal all joints with Teflon tape and check for leaks.
Step 8: Connect the Power Source
- For gas units, connect the gas pipe with a leak-proof joint compound and perform a soap test to detect leaks.
For electric units, connect wiring according to the manufacturer’s schematic, using appropriately rated circuit breakers.
| Note Only a licensed technician should handle electrical or gas connections for tankless water heater installation for warranty and safety compliance. |
Step 9: Install Exhaust Vents & Condensation Lines
Proper venting ensures your system operates safely and efficiently.
- Use stainless steel or PVC pipes for intake and exhaust lines.
- Follow local building codes for vent termination distance and slope.
- Install a condensation drain line connected to the nearest floor drain or sump.
This prevents exhaust backflow and moisture damage for tankless water heater installation.
Step 10: Purge Air and Test the System
Turn on your home’s water supply and open hot water taps to let air escape. Once water runs smoothly:
- Restore gas or electrical power.
- Run the system to check for stable water temperature.
- Inspect connections for leaks, drips, or unusual noises.
If everything checks out, your tankless water heater installation is complete!
Post-Installation Tips & Maintenance
To maximize your heater’s lifespan (typically 15–20 years):
- Flush the system annually to remove mineral buildup.
- Clean air and water filters every 3–6 months.
- Check for error codes displayed on the unit.
- Schedule a professional inspection yearly for safety and efficiency.
| Fun Fact Proper maintenance can improve energy efficiency by 15–20% and reduce utility bills over time. |
Safety Reminders
Always install a carbon monoxide detector near gas water heaters.
A yellow flame indicates incomplete combustion — call a technician immediately.
Never attempt gas line repairs without a licensed professional.
Your safety and your family’s comfort depend on professional expertise and code compliance.
Conclusion
A tankless water heater installation is more than just a home upgrade — it’s an investment in year-round comfort, safety, and efficiency. By understanding each step, from selecting the right model to final testing, you can better appreciate the work professionals do and ensure your system performs at its best.
If you’re considering installation or need expert guidance, contact Heatwave Water Heater Service — your trusted partner for professional, safe, and certified installation. Stay warm, stay efficient, and enjoy endless hot water this winter.
FAQs
Q1: How long does it take to install a tankless water heater?
Installation usually takes 4–6 hours, depending on your home’s setup and whether modifications are needed for gas or electrical connections.
Q2: How long does a tankless water heater last?
A properly maintained unit can last 15–20 years, which is about twice the lifespan of traditional tank models.
Q3: What maintenance does it require?
Perform annual descaling, clean air and water filters, and have the system professionally inspected once a year.
Q4: Can I install a tankless water heater myself?
While minor prep work is possible, gas and electrical connections must be done by licensed technicians to ensure safety and code compliance.
Q5: Is a tankless water heater worth the cost?
Yes — while the upfront installation cost is higher than traditional tanks, a tankless water heater offers long-term savings through improved energy efficiency, reduced standby heat loss, and a lifespan of up to two decades. You’ll also enjoy unlimited hot water and lower maintenance expenses over time, making it a smart investment for most modern homes.