Looking for tips on how to install tankless water heater models safely, with the best efficiency, and no expensive errors for your own home? Once you have your desired setup figured out, from hardware to software, to estimate and configure, this guide will tell you all you need to know. One reason tankless water heaters have become popular is that they provide an endless stream of hot water while reducing energy costs and the amount of space needed for installation. However, installing one isn’t as easy as just swapping out your old tank. These big systems have to be properly vented, have an upgraded gas or electric supply, and be installed to meet local building codes.
From selecting the right unit through mounting, connecting, and getting your system up and running, this all-inclusive guide covers it all. You’ll also learn when it’s best to handle the work yourself and when you should call a professional.
What Is a Tankless Water Heater?
A tankless water heater is a small unit that provides hot water as needed without heating and storing it in a tank. When you open a faucet, water passes over internal heating elements or a gas burner and quickly heats to the temperature you specify. Since it does not keep water, the system provides two big benefits: endless hot water and dramatically less energy waste.
These “on-demand” systems usually last about 20 years and are therefore more cost-effective, considering the lifespan of traditional tanks is almost half that. They also reclaim space in laundry rooms, garages and closets. Most importantly, homeowners enjoy having the convenience of multiple fixtures at once, which will vary based on the size and the flow rate that you select.
Key Factors to Consider Before Installation
Planning is key before you start any tankless water heater installation. These units are different from old-style tank heaters, and if you skip this step, it can cause leaks, error codes, or even unsafe configurations.
1. Correct Sizing and GPM (Gallons Per Minute)
Tankless systems are sized according to the total hot water you need at one time. A small tankless unit can supply one shower at a time, while a whole-house unit can supply several bathrooms and appliances. Check your home’s expected flow rate and the “temperature rise,” or how much the water heater needs to raise the temperature of the incoming water. More potent units are required for cooler weather.
2. Gas Line or Electrical Capacity
Tankless units consume a lot of energy. Gas units generally require a ¾-inch line, along with a high BTU rating meter. Electric models require multiple dedicated breakers, usually 40 or 60 amps each. If you do not have a powerful enough system in your home, you will need to upgrade.
3. Proper Venting Requirements
Gas units must vent to the outdoors. That old tank vent cannot be reused. High efficiency models use PVC or CPVC, standard models use stainless steel vent pipe. Your vents need to be vented properly to avoid carbon monoxide, which is one of the most important safety considerations.
4. Hard Water Issues
Mineral buildup can damage the heat exchanger. If you have hard water in your house, a softener is highly recommended.”Shady Grove is the No. 1 reason we’re having a Hell of a time finding a place to live for two grown men. Can’t recommend them enough to protect your investment.”
Tools and Materials You’ll Need
Before you begin, gather all the necessary tools so that you won’t have to stop midway to get them.
Basic Tools
- Adjustable wrench
- Pipe cutter
- Drill with bits
- Screwdrivers
- Pipe wrench
- Level
Plumbing Materials
- Copper or PEX pipe Work
- Shut-off valves Work
- Isolation valve kit Work
- Teflon tape Work
- Pipe sealant Work
Electrical or Gas Supplies
- Gas shut-off valve Work
- Sediment trap Install work
- Venting materials Work
- Proper wiring and breakers Requirements for Wiring and Fuses
- Wall thimbles Installations
Step-by-Step Guide: How to Install Tankless Water Heater
You can now follow step-by-step guides on systems for how to install tankless water heater. The procedure is a little different for gas and electric models, so make sure you read through the appropriate section.
Turn off the water supply, gas line (for gas units), and power before you begin your project.
Installing a Gas Tankless Water Heater
Performance and long-term operating costs have caused most homeowners to select gas units. Here is how to do tankless gas water heater installation safely:
Step 1: Remove the Old Tank
Drain the heater completely, disconnect the gas and water lines, then remove the tank. Clean and inspect the wall for mold, soot, or moisture damage.
Step 2: Mount the New Unit
Attach a plywood backer board to the wall if needed. Use a level to level.” Align with the horizontal picture frame point of reference. When installing, use manufacturer-supplied brackets — these units can be heavy when full, so a solid mounting point is a must.
Step 3: Connect Water Lines
Connect the cold inlet and hot outlet with copper or PEX. Utilize an isolation valve kit to flush the system with vinegar on an annual basis to get rid of scale. This modest modification increases lifetime and safeguards the heat exchanger.
Step 4: Install the Gas Line
Bring in a properly sized gas line to the heater. Attach a sediment trap for the debris. Check pressure with a manometer, test with soapy water. When bubbles appear, leaks have been detected and need to be repaired before lighting.
Step 5: Venting the Unit
Install the exhaust vent through an outside wall or ceiling. Observe minimum distances from windows, doors, and air vents. Acidic condensation must be drained away in the drain lines of condensing units.
Step 6: Power Up and Test
Plug into a grounded outlet. Open the water valves, test for leaks, bleed the system, and light the burner. Set temperature— 120°F is a safe standard.
Installing an Electric Tankless Water Heater
What to Expect from Your Tankless Hot Water Heater Installation. If you are more electric system, then your “tankless water heater installation” will be different.
Step 1: Check Electrical Capacity
Electric tankless systems usually need 2 or 3 dedicated breakers. Make sure your panel will support the load. If not, a panel upgrade may be necessary.
Step 2: Mount the Heater
Place the unit in a clean and dry location on the wall. Electric are generally more compact and easier to locate.
Step 3: Connect Water Lines
Connect the unit to your main water line. Add shut-off valves and comply with your local codes, and enclose a pressure relief valve if applicable.
Step 4: Wire the System
Choose the right wire gauge for your water heater’s specifications. Connect the wires to the terminal blocks in the heater and ground properly.
Step 5: Flush and Test
Pass water through the device first – an electric heater should never be propelled before water is flowing, because “dry firing” can destroy the heating elements. Now throw the breakers and adjust the temperature.
You can read about: How to Install a Heat Pump Water Heater
Installation Cost Breakdown
The price of a tankless water heater install will vary depending on region, unit size, and home modifications.
Item Estimated Cost
Electric Unit $500–$1,200
Gas Unit $800–$2,500
Professional Labor $600–$1,500
Gas Line Upgrade $300–$800
Venting $200–$500
Electric models are less costly to install but have higher operating costs. Gas units involve more parts and labor up front, but the long-term savings are superior.
Common Installation Mistakes to Avoid
Even seasoned DIYers can screw up BIG time. Look out for these:
- Undersized gas lines → cause ignition failure, cold water
- Skipping isolation valves → allows descaling but shortens life
- Incorrect venting materials → fire hazard and carbon monoxide exposure
- Improper vent slope →condensation may fall into the burner
- Failing to install an expansion tank on closed systems
These errors can be expensive to fix, and in some cases, more costly than just hiring a pro in the beginning.
When to Call a Professional
Since the installation requires electricity, high heat, and flammable gas, the safer bet is to hire a professional. A good plumber is familiar with code, venting, and sizing.
If you’re in Eagle Rock, businesses such as Derks Plumbing will deliver and install your tankless system with the confidence that we will ensure your system is safe and reliable, and that we stand behind our work through warranties, permits, and inspections. Look for contractors who:
- Are licensed and insured
- Provide written estimates
- Offer labor warranties
- Have experience with your brand
- Are knowledgeable of local codes
Conclusion
Knowing What Goes Into How to Install Tankless Water Heater Systems can make you value your work even more, whether you decide to Do It Yourself or not. These units provide the convenience of unlimited hot water, increased efficiency and long-life service, but they need to be planned ahead of time, scheduled and very carefully installed. Follow the instructions in this article or have a reputable professional do so, and you’ll be sure that your new system will serve you well, safely, efficiently and dependably for years to come.
FAQs
Do you need a permit to replace a water heater?
Yes. Most cities require a permit for that kind of work to make sure your venting, plumbing and gas line installation is safe.
Can I use my old vent from my traditional tank water heater?
No. Tankless systems must use ‘contemporary’ venting solutions that are sealed.
How often should I service my tankless water heater?
Flush the system every year to remove mineral deposits.
Would my tankless water heater work without power?
No. Both gas and electric models require power.
Are tankless water heaters worth the cost?
Yes. Up to 30% energy savings, longer life and endless hot water.
