How to Switch from Tank to Tankless Water Heater

To switch from a tank water heater to a tankless water heater, first turn off the power and water supply, then disconnect the tank heater, install the tankless unit according to the manufacturer’s instructions, ensuring proper venting and plumbing connections, and finally, restore the power and water supply to test the system.

Upgrading to a tankless water heater can save energy, space, and money over time. This guide covers everything from sizing to installation for a successful conversion.

Transforming from tank to tankless water heater: a seamless upgrade journey.

When to Make the Switch

Consider switching when:

  • Your current tank is 8+ years old
  • You need more hot water capacity
  • Energy bills are rising
  • Space is limited

Tankless units last 20+ years compared to 10-15 for tanks. Newer models achieve up to 94% energy efficiency versus 70% for standard tanks.

Illustrate a modern tankless water heater installation in a cozy home setting.

Choosing the Right Tankless Water Heater

Gas vs Electric

Gas models provide higher flow rates but require proper venting. Electric units are easier to install but may need upgraded wiring. Compare gas and electric water heaters to find your best option.

Sizing Your Unit

Calculate your peak demand:

Fixture Flow Rate (GPM)
Shower 2.0-2.5
Dishwasher 1.0-2.0
Washing Machine 1.5-2.5

Add up simultaneous uses to determine required capacity. For whole-house systems, consider a unit with recirculation pump.

Installation Process

1. Remove Old Water Heater

  1. Turn off water supply and power/gas
  2. Drain the tank completely
  3. Disconnect all plumbing and electrical
  4. Remove the unit (may require help)

2. Prepare for New Installation

Gas models often need:

  • Larger gas line (typically 1″ diameter)
  • Proper venting (stainless steel recommended)
  • Combustion air supply
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Electric models may require:

  • Dedicated 240V circuit
  • Upgraded electrical panel
  • Proper wire gauge

3. Mount and Connect New Unit

Follow manufacturer instructions for:

  1. Wall mounting (use sturdy brackets)
  2. Water line connections (use dielectric unions)
  3. Gas/electrical connections
  4. Vent installation (for gas models)

According to Department of Energy, professional installation is recommended for most tankless conversions.

Post-Installation Considerations

Maintenance

Annual flushing prevents mineral buildup. Use a quality descaling solution for best results.

Temperature Settings

Set between 120-140°F. Higher settings reduce efficiency and increase scaling. Learn ideal temperature settings for your needs.

Water Pressure

Tankless units require minimum flow rates to activate. Consider low-flow fixtures if you experience intermittent operation.

Cost Considerations

Typical costs include:

  • Unit: $600-$3,000
  • Installation: $1,000-$3,000
  • Upgrades (gas/electrical): $500-$2,000

According to Consumer Reports, tankless heaters can save $100+ annually on energy bills.

Common Challenges

Be prepared for:

  • Cold water sandwich effect (brief cold between hot)
  • Higher upfront costs
  • Possible need for water softener in hard water areas
  • Longer wait for hot water at distant fixtures
Joye
Joye

I am a mechanical engineer and love doing research on different home and outdoor heating options. When I am not working, I love spending time with my family and friends. I also enjoy blogging about my findings and helping others to find the best heating options for their needs.