Install Water Heater: Step-by-Step Guide

Struggling with a faulty water heater can leave you in the cold. On average, water heaters need replacing every 10 to 15 years to ensure reliable hot water. Our step-by-step guide will show you how to install a new water heater confidently and safely.

Discover how simple it can be!

Preparations for Water Heater Installation

Before diving into the installation of a new water heater, one must ready their workspace and gather all necessary tools. This crucial stage ensures safety measures are set and materials are at hand to facilitate a smooth transition from the old system to the new.

Tools and Materials Required

Gathering the right tools and materials is crucial for a successful water heater installation. Make sure you have everything you need before starting to avoid any interruptions.

  • Adjustable wrench: You’ll need this to loosen and tighten various nuts and bolts.
  • Pipe wrench: This tool helps grip and turn pipes during installation or removal.
  • Screwdrivers: A set of screwdrivers will be essential for attaching screws and adjusting electrical connections.
  • Voltage tester: Use this device to ensure the power supply is safely disconnected before working on an electric water heater.
  • Teflon tape: Wrap this around threads of pipe fittings to prevent leaks.
  • Copper tubing: Required for connecting the water heater to the existing plumbing system, especially if soldering is necessary.
  • Copper adapters and fittings: These help in securely joining pipes together.
  • Soldering supplies, such as soldering paste and flux, if you plan on securing copper pipe connections with heat.
  • Dielectric unions: Use these to prevent corrosion between different types of metal pipes.
  • Pipe insulation: Keeps hot water pipes from losing heat quickly after installation.
  • Garden hose: Useful for draining the current water tank before removal.
  • Steel pipe or flexible hoses for gas units: Essential for gas water heater installations to carry gas safely to the unit from the supply line.
  • Draft hood (for gas heaters): Ensures proper airflow and directs exhaust gases safely into a chimney or vent pipe.

Disconnect Electricity or Gas

Before starting your water heater replacement, you need to ensure safety by disconnecting the power. For an electric water heater installation or a gas unit, shutting off the power is critical.

Drain Current Water Tank

Draining the current water heater tank is essential before installing a new unit. Follow these steps to safely empty the old tank and prepare for removal.

  • Turn off the power supply to your water heater at the fuse box, ensuring your safety during the process.
  • Locate the temperature and pressure relief valve on your water heater. Attach a garden hose to the valve’s discharge pipe.
  • Lead the other end of the hose to a drain or outside area where hot water can safely empty without causing damage or harm.
  • Open the pressure relief valve by lifting its handle. This action breaks any vacuum seal within the tank and allows water to flow freely.
  • Go to your nearest tap or spigot connected to the hot water system. Open it to allow air into the system, aiding in draining.
  • Return to your heater and open the ball valve or drain cock at the bottom of the tank. Water will now start flowing through the hose.
  • Allow time for all water inside the tank to drain out completely. Keep an eye on this process, as it may take some time depending on tank size.
  • After all water has drained, close both valves: first, reseal your temperature and pressure relief valve; then shut off your ball valve or drain cock.
  • Disconnect and remove your garden hose from your heater, tidying up any spillage that occurred during drainage.

Removing the Old Water Heater

Before installing your new unit, the task of safely disconnecting and shifting away the old water heater is paramount. It involves a systematic approach to detaching all electrical and plumbing connections prior to lifting out the tank with caution.

Disconnect Electrical Connections

Safety comes first when handling water heater installations. Always turn off the power at your home’s main circuit breaker to ensure no electrical hazards occur.

  • Locate your consumer unit and switch off the supply to your water heater.
  • Use a voltage tester to make sure there is no power running to the water heater.
  • Unfasten the screws or bolts securing the access panel on the old water heater using a screwdriver or spanner.
  • Carefully detach wires from screw terminals or disconnect any plug connections inside.
  • Use pliers or a wire stripper if you need to free wires from tight spaces.
  • Tape off loose wire ends with insulating tape to avoid accidental contact until you’re ready to connect them again.
  • Keep track of what wire connects where, perhaps by taking a photo or labelling them, for easier reinstallation later.

Disconnect Plumbing

Disconnecting the plumbing is vital in removing an old water heater. Follow these steps carefully to avoid water leaks and ensure safety precautions are met.

  • Shut off the water supply at the main valve to prevent any water flow into your home.
  • Locate the valves above your heater and close them to stop water from entering or leaving the tank.
  • Open a hot water tap nearby to relieve pressure in the system; this will help drain the tank faster.
  • Use an adjustable wrench to loosen the nuts that connect both hot and cold – water lines to the heater.
  • Have a bucket ready underneath to catch any residual water as you disconnect the pipes.
  • Carefully unscrew and remove each pipe, starting with hot water outlets, then moving on to cold – water inlets.
  • If fixtures are soldered directly to supply lines, heat them with a torch until solder melts. Once molten, pull away fittings using pliers.
  • Employ plumbers tape when unscrewing joints to protect threads and minimise damage.
  • Clean all exposed pipe ends once disconnected, ensuring debris doesn’t enter your new heater during installation.

Safely Remove Old Tank

Safely removing the old water heater is crucial to avoid any damage or injury. Ensure you have adequate space and a clear path for tank removal.

  • Turn off the power supply to your water heater at the consumer unit to eliminate any electrical hazard.
  • Close the cold – water inlet valve to stop more water from entering the tank.
  • Attach a garden hose to the drain valve at the bottom of the tank, leading it outside or into a suitable drain.
  • Open hot water taps in your home to allow air into the system, which helps emptying the tank quicker.
  • Drain all water from the tank by opening its drain valve; this could take some time if there’s sediment build-up.
  • Cut off any soldered pipes with a tubing cutter, taking care not to damage existing plumbing lines.
  • Use two spanners when disconnecting threaded steel pipes, one to hold and another to turn. This avoids twisting and breaking connections.
  • If your water heater has a pressure – reducing valve, remove it carefully. It may require replacement before installing a new unit.
  • With help, tilt and lift the old tank away from its position, keeping your back straight and lifting with your legs. Water heaters are heavy; never attempt this alone.
  • Ensure that no residual water leaking occurs onto the floor as you move out of place. Have towels ready for any spills.

Installing the New Water Heater

When it comes to installing the new water heater, meticulous attention to detail is crucial for ensuring a safe and efficient set-up; continue reading to master this process.

Prepare Plumbing Lines

Before installing the new water heater, preparing your plumbing lines is vital. These steps ensure a seamless fit and no leaks in the future.

  • Shut off the main water supply to avoid any accidents or spills. Ensure all faucets are closed to maintain pressure.
  • Identify the old pipes attached to your previous tank. Inspect them for wear or damage.
  • Remove any insulation on the pipes carefully. Keep it intact for re – use after installation of the new heater.
  • Use plumbing tools to loosen and detach solder fittings if present. Replace with new ones if they show signs of corrosion.
  • Clean pipe ends with soldering flux before attaching new fittings. This helps create a strong bond when soldered.
  • Cut lengths of polyvinyl chloride (PVC) pipes if needed using a designated cutter. Smooth edges with sandpaper for a snug fit.
  • Install thermostatic mixing valves as per manufacturer instructions. They control temperature and prevent scalding.
  • Apply plumber’s tape on threads of connections to ensure they are watertight. It provides extra sealing and eases future disconnections.
  • Securely attach new copper pipes or PVC lines by matching them to corresponding outlets on the water heater. Double-check alignments.
  • Solder joints where necessary, applying heat evenly around the joint until the solder flows freely into the gap.
  • Tighten all connections with wrenches but do not over – tighten as this might damage threads or fittings.

Connect Electrical Wiring

Connecting the electrical wiring of your new water heater is a critical step in the installation process. It ensures that your unit works properly and safely heats water for your home. Here’s how to do it:

  • Turn off all power at the circuit breaker before starting any work to avoid electric shock.
  • Remove the cover plate on the water heater’s access panel to expose the terminals for wiring.
  • Strip half an inch of insulation from the ends of the wires if they are not already prepared.
  • Connect the ground wire, usually green or bare, to the designated grounding screw on the heater.
  • Match and connect the supply wires with those in the water heater—commonly, black leads to black (hot) and white to white (neutral).
  • Ensure each connection is tight using wire connectors, also known as wire nuts, twisting them clockwise until secure.
  • Wrap any exposed connections with electrical tape as a precaution against short circuits.
  • Carefully position all wires inside the compartment so that they do not get pinched when you replace the access panel cover.

Attach the Supply Lines & Turn On the Water

Attaching the supply lines to your new water heater is a critical step. Ensure all connections are secure to prevent leaks.

  • Position the water heater close enough to the supply pipes for easy access.
  • Use plumbing tools and materials to fit the cold water line to the designated inlet valve on your tank.
  • Wrap thread seal tape around the threads of the water inlet and outlet before connecting. This helps create a watertight seal.
  • Tighten each fitting with an adjustable wrench, but take care not to over – tighten and damage the threads.
  • Repeat similar steps for attaching the hot water line to the outlet valve on your heater.
  • Check every joint and connection for any signs of gaps that could lead to leaks.
  • Open the shut – off valves to allow water into your new heater, filling it gradually.
  • Keep an ear out for unusual noises which might indicate issues with water flow or pressure during this process.
  • Observe all connections closely as the tank fills. Look for drips or moisture that may suggest a leak needs fixing.

Considering an Upgrade to Tankless Water Heater

Switching to a tankless water heater can provide several benefits, including continuous hot water and potential energy savings. Tankless models heat water directly without the need for a storage tank, delivering a constant supply of hot water on-demand.

This makes them perfect for homes where space is at a premium as they are much smaller than traditional tanks.

Before making the change, it’s essential to evaluate your household’s hot water needs. A professional installation ensures that your new system matches your family’s consumption patterns while adhering to safety standards.

Tankless heaters also reduce the risk of leaks and flooding associated with old tank systems because there isn’t a large volume of stored water. With proper maintenance, these modern heating solutions offer longevity and reliable performance throughout their lifespan.

For Gas Water Heaters: Additional Steps

When installing a gas water heater, there are extra measures to take that ensure safety and efficiency. This part of the process demands careful attention to ventilation and gas connections, vital for preventing hazards such as carbon monoxide exposure.

Install Vent Hood and Vent Piping

Installing a vent hood and proper vent piping is crucial for a gas water heater installation. It ensures harmful gases like carbon monoxide are safely expelled from your home. Here’s how you should go about it:

  • Choose the correct vent hood size to match your water heater’s specifications. The right fit prevents hazardous fumes from leaking.
  • Place the vent hood securely over the exhaust port on top of the water heater. This needs to be done carefully to ensure a tight fit.
  • Check for any obstructions in the area where you plan to run the vent pipes. Make sure the path is clear to promote efficient airflow.
  • Measure the distance between the water heater and where you’ll vent outside. This helps you purchase enough piping without excess wastage.
  • Cut your vent pipes according to measurements taken, allowing for slight adjustments if necessary. Accurate cutting reduces complications during fitting.
  • Join each pipe section firmly with appropriate fittings as recommended by heating codes. Use screws or foil tape designed for high temperatures to seal them together.
  • Keep all joints secure and check for gaps that could leak exhaust gases into your home. Ensuring a perfect seal safeguards against carbon monoxide poisoning.
  • Run your piping along walls or ceilings towards an outdoor area, avoiding kinks and angles that are too tight, which can restrict gas flow.
  • Drill a hole through an exterior wall with a diameter slightly larger than your piping for easy passage. Take care not to compromise structural integrity.
  • Install any required insulation around the piping if it passes through unheated areas, reducing heat loss and condensation which can corrode pipes over time.
  • Securely attach the pipe exit on the exterior wall, sealing around it with caulk or other suitable materials approved for outdoor use.

Install the Gas Line

  • Shut off the gas valve before starting to prevent any gas leaks or hazards.
  • Confirm compatibility between your water heater and home’s gas type—natural or propane.
  • Gather all necessary tools, which include a pipe wrench, PTFE tape, flexible gas hose, and leak detection solution.
  • Use PTFE tape specifically designed for gas lines on threaded connections to ensure a tight seal.
  • Connect the flexible gas supply line to the tank’s dedicated gas valve. Tighten this connection with your wrench.
  • Secure the other end of the gas line to the home’s main gas supply. Use steady pressure and tighten it firmly.
  • Test every joint with leak detection solution by applying it over connections and looking for bubbles that indicate leaks.
  • Once correctly fitted, slowly turn on the main gas valve to allow flow into your new water heater.
  • Observe all connections for a few minutes to confirm there are no signs of leaking gas.
  • If you detect a leak, shut off the main valve immediately and check all connections again after fixing any issues.

Testing the New Installation

Testing the new installation is a crucial step in ensuring your water heater operates safely and efficiently. It involves verifying the system’s integrity, from checking for any leaks to confirming that all components function as intended before regular use.

Bleed Hot Water Lines

Bleeding hot water lines is a crucial step to remove trapped air that can cause rumbling noises and erratic water temperatures. Carry out this process with care to ensure your new water heater functions efficiently.

  • Identify the bleed valves on your radiators or the highest faucets in your home.
  • Open one bleed valve or faucet at a time, starting with the lowest level of your property.
  • Listen for a hissing sound which indicates air escaping from the lines.
  • Wait until a steady stream of water flows from the valve or faucet, showing that most of the air has been expelled.
  • Close the valve or turn off the faucet before moving to the next one; repeat this process for each level of your home.
  • Check all radiators if you have a hydronic heating system; they often have individual bleed valves.
  • Adjust temperature settings as needed once all air has been bled from the system.
  • Monitor pressure gauges if available, as bleeding can affect system pressure and may require adjustment.

Check for Leaks

Ensuring your newly installed water heater is leak-free is crucial for its safe operation. Carefully inspect all connections after installation to prevent water damage and maintain efficiency.

  • Examine all pipe connections around the water heater. Look for any droplets of water or damp spots that may indicate a leak.
  • Use your hands to feel along the pipes and joints. Moisture or a change in temperature can imply that water is escaping from these points.
  • Observe the area beneath the tank for any signs of water pooling. Even small amounts could suggest a slow leak that needs attention.
  • Wipe down all connections with a dry cloth. Return after a few minutes to see if any wetness has reappeared, which would signal a possible leak.
  • Check the pressure relief valve, which might release water if there’s too much pressure inside the tank. Ensure it’s functioning correctly and not leaking persistently.
  • Inspect areas where supply lines connect to the water heater. Make sure they are snugly fitted and properly sealed.
  • Apply soapy water to suspected areas of leakage. Bubbles forming when gas or hot air passes through soap indicate a potential leak point.
  • Test connection points using professional equipment if available. Some leaks might be too small for visual detection but could become larger issues over time.

Light the Pilot Light (for gas heaters)

Lighting the pilot light is a crucial step in the installation of a gas water heater. It ensures that your heater can start heating water immediately.


Embarking on the journey of water heater installation can significantly improve your home’s comfort level. Follow each step carefully to ensure a smooth and secure setup. Remember, handling gas connections and electrical wiring demands extra caution; consider getting professional help if you’re unsure.

Once installed, relish the consistent supply of hot water that awaits you. Your diligence in this DIY task pays off with every warm shower or bath you take.

If you’re considering a more efficient water heating system, explore our guide on upgrading to a tankless water heater.


1. How do I get started with installing a new water heater?

First, you need a detailed installation guide to safely remove your old water heater and then properly plumb the new one into your home system.

2. What should I regularly do to maintain my water heater?

Regular water heater maintenance includes checking for leaks, ensuring the temperature is set correctly, and flushing out sediment from the tank.

3. Is there anything I should check online before starting the installation process?

Yes, always fact-check for any updates or specific instructions on manufacturer websites using browsers like Internet Explorer just before beginning work on your water heater.

4. If I have trouble during installation, how can I confirm what to do next?

If issues arise, refer back to your step-by-step guide or seek professional help where required—you may need a one-time password or code for secure assistance depending on your device model.

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