Installing a tankless water heater: a step-by-step guide

If you're tired of running out of hot water during your showers or want to save on energy bills, installing a tankless water heater can be a great solution.
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Tankless water heaters, also known as on-demand water heaters, provide hot water as needed, making them energy-efficient and space-saving. In this guide, we'll walk you through the process of installing water heater tank.

What You'll Need

Before you begin, gather the necessary tools and materials:

Water tankWater tank
Water tank
  1. Tankless Water Heater: Choose the right size and type for your home's hot water needs.
  2. Gas Line (if applicable): For gas-powered tankless heaters, ensure you have the correct gas line size and compatible fittings.
  3. Venting Kit (if applicable): Venting kits are needed for indoor gas tankless water heaters.
  4. Water Shut-off Valves: You'll need both cold and hot water shut-off valves.
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pictures from Golborne and Lowton in decades past
  1. Pipes and Fittings: Depending on your plumbing, you might need pipes and fittings.
  2. Electric Wiring and Breaker (if applicable): Electric tankless heaters require proper wiring and a dedicated breaker.
  3. T&P Relief Valve: A temperature and pressure relief valve is a safety requirement.
  4. Pipe Insulation and Teflon Tape: Insulate pipes and use Teflon tape for sealing threads.
  5. Screws and Anchors: For securing the unit and other components.
  6. Pipe Cutter and Wrenches: Tools for cutting and connecting pipes.
  7. Drill and Bits: For mounting the unit securely.

Step 1: Choose the Location

Select a suitable location for your tankless water heater. It should be near the main water supply and close to the electrical or gas connection. Make sure it's well-ventilated and offers easy access for maintenance.

Step 2: Turn Off Utilities

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Before you begin any work, shut off the water, gas, and electricity to your existing water heater. If you're replacing a traditional water heater, drain it completely.

Step 3: Mount the Unit

Secure the tankless water heater to the wall using the provided mounting brackets and anchors. Ensure it's level and stable.

Step 4: Connect Water Lines

Connect the cold water supply line to the inlet and the hot water line to the outlet on the unit. Use shut-off valves on both lines for easy maintenance and repairs.

Step 5: Venting (for Gas Heaters)

If you have a gas tankless water heater, install the venting kit according to the manufacturer's instructions. Proper venting is essential for safety and efficient operation.

Step 6: Gas and Electric Connections

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For gas tankless water heaters, connect the gas line to the unit, ensuring a secure fit with the appropriate fittings. If you have an electric unit, connect the wiring to the dedicated breaker and follow the electrical code.

Step 7: Pressure Relief Valve

Install the temperature and pressure relief (T&P) valve on the hot water outlet. Run a discharge line from the T&P valve to a suitable drain or outside.

Step 8: Pipe Insulation and Sealing

Insulate the hot water pipe to prevent heat loss. Use Teflon tape on threaded connections to prevent leaks.

Step 9: Turn On Utilities

Turn on the water supply, gas, or electricity to the tankless water heater. Check for any leaks, and ensure the unit is functioning correctly.

Step 10: Set the Temperature

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Adjust the temperature settings on your tankless water heater to your desired hot water temperature. Most units have user-friendly controls.

Step 11: Test the Water Heater

Turn on hot water taps in your home to ensure the unit is delivering hot water as expected. Check for any fluctuations in temperature.

Step 12: Maintenance

Regularly flush your tankless water heater to remove mineral buildup and maintain its efficiency. Consult the manufacturer's guidelines for specific maintenance requirements.

Installing a tankless water heater can be a DIY project for those with plumbing and electrical experience. However, if you're unsure, it's advisable to hire a professional plumber or electrician for a safe and efficient installation.

Enjoy the benefits of endless hot water and lower energy bills with your newly installed tankless water heater.