Having hot water available at all times is essential for any home. Water heaters provide reliable, convenient access to hot water for showers, washing dishes, doing laundry, and much more. While most homeowners rarely think about their water heater as long as it’s functioning properly, there will eventually come a time when you need to replace your existing unit. Installing a new water heater may seem intimidating, but it’s actually a very manageable DIY project for most homeowners if you follow some key preparation and safety steps.
This comprehensive guide will walk you step-by-step through the entire process of replacing your old water heater with a new, more efficient one. We’ll cover everything from choosing the right replacement, to properly preparing the installation location, safely removing the old unit, securing and connecting the new system, and testing your work. With a bit of planning, the right tools, and this tutorial, you can upgrade your water heating in just one day.
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Choosing a New Water Heater
Before starting any installation work, you first need to select the best replacement water heater for your home’s needs. Water heaters come in a variety of fuel types, capacities, and configurations. Key factors to consider are:
Fuel Type
The most common residential water heater types are:
- Electric
- Natural Gas
- Propane
- Oil-fired
Consider which fuel options are available in your home and which will be the most affordable long-term based on local energy costs. If you currently have a gas line to your water heater, replacing with a gas model may be the simplest option.
Tank vs Tankless
Traditional tank water heaters store 30-50 gallons of pre-heated water. Tankless heaters provide unlimited hot water on demand without a storage tank. Tankless models are more energy efficient but have higher upfront costs.
Capacity
Make sure to choose a tank capacity adequate for your household’s peak hot water demand. Generally, follow these guidelines:
- 2-3 people = 30-40 gallon tank
- 4+ people = 40-50+ gallon tank
Higher capacity means fewer occasions of running out of hot water.
Energy Factor
Select a model meeting the latest Energy Star efficiency standards. Compare Energy Factor (EF) ratings. The higher this number, the more efficient the unit.
Once you select an appropriate replacement water heater for your needs, set the new unit and any required plumbing or electrical supplies in the install location to acclimate to room temperature for at least 24 hours before beginning the installation.
Preparing the Installation Area
With the new equipment ready to go, now properly prepare your space:
Clear the Area
The area around the water heater should be free of clutter or furniture to allow easy access on all sides during servicing. Leave a minimum clearance of 1 foot around the perimeter of the unit. For gas models, follow clearance guidelines in the manual to ensure adequate ventilation.
Protect Floors and Walls
Place drop cloths or tarps around the floor beneath and walls behind where the water heater sits to catch any drips or leaks during installation. For easier cleanup, you can also lay down plastic sheeting before beginning work.
Gather Tools/Materials
Have everything you need ready and on hand before turning off home water supply lines or disconnecting any components. Useful items include:
- Wrenches
- Pliers
- Screwdrivers
- Teflon tape
- Emery cloth/steel wool
- Bucket to catch water when flushing lines
- Rags, sponges, and towels
Turn Off Power to Unit
Locate the circuit breaker supplying power to your electric water heater and turn it OFF. This prevents accidental electric shocks while you work around the electrical connections.
With your workspace prepped and tools at the ready, it’s time to remove the old heater.
Removing the Old System
Start by shutting off water supply lines and draining the tank. This may involve a few simple steps for some installations or numerous valves/pipes for more complex systems:
- Locate Water Supply Shutoff Valve(s)
For basic setups, there will be just one shutoff valve along the cold inlet water line. Turning this OFF stops flow into the tank.
For connections shared with other household water fixtures, you may need to shut off the main home supply line. - Turn Off Fuel to Heater
For gas water heaters, rotate the exterior gas supply valve clockwise to the OFF position.
For electric heaters, the power should already be OFF at the breaker panel as a safety precaution. - Open Hot Water Faucets
Open all faucets fed by the water heater system (sinks, showers, etc) to allow faster drainage. - Drain Tank
Attach a garden hose to the tank drain valve and route it to a drain or into buckets to catch all water spillage. Then open the drain valve and allow the tank to completely empty.
CAUTION: Released water may initially be very hot! Keep your hands clear.
Once fully drained, detach all water lines to fully free the old unit for removal:
- Disconnect Water Lines
Using pliers and wrenches, detach the cold inlet and hot outlet pipes threaded into the tank fittings, as well as any secondary recirculation lines. Have a towel on hand to catch drips. - Remove Temperature-Pressure Relief Valve
Detach any discharge pipes from the T&P valve on the tank sidewall, then fully unscrew the valve. Set this aside to reinstall later. - Disconnect Gas Line (For gas models)
Using proper-sized wrenches, loosen the threaded gas supply connector at the heater inlet. - Disconnect Electrical Wires (For electric models)
Unscrew or clip any wire terminals that join to electrical terminals on the tank. Carefully pull wiring out of the way.
With all connections detached, the old water heater can now be safely taken out of position. Depending on the model style and location, this usually requires 2+ people and an appliance dolly or hand truck.
Installing the New Water Heater
Installation is essentially the reverse process of removal. Follow these best practices when placing your new system:
- Set the tank in the cleared space and adjust leveling legs to ensure it sits evenly front-to-back and side-to-side. Secure to wall studs if desired.
- Ensure the T&P valve, thermostat dials, and all connection points will be conveniently accessible when in position.
- Allow proper clearance from walls, floor, vent openings, etc. Consult manual for specific requirements of your model.
Before making any permanent pipe or electrical connections inspect key components:
Inspect T&P Valve
Examine the pressure relief valve on the new tank to verify the discharge outlet has no blockage/obstructions. Leaving this clear is critical for safe pressure release in an overheat event.
Review Manual
Read your specific installation guidelines to confirm required clearances, approved connection fittings, and any model-specific steps related to venting, condensate drains, leak detection, or thermostat programming.
When aligned, leveled, and prepped, complete all plumbing, fuel, and electrical linkages:
- Connect Water Lines
Cut or utilize flexible water line connectors to join the cold inlet and hot outlet fittings on the tank to home pipe stubs. Use Teflon tape on threaded joints to prevent leaks. - Reinstall T&P Valve
Thread the temperature-pressure relief valve back into the allotted sidewall port on the new tank. Run the discharge pipe to within 6 inches of the floor or into a drain pan. - Attach Gas Piping (For gas models)
Using an approved pipe sealing compound, reconnect the gas supply line to the heater’s gas valve/control. - Connect Electrical Wiring (For electric models)
Splice any electrical supply wires into the provided power terminals, following wiring diagram in the manual as a guide. Replace any damaged wire insulation.
Testing & Completing the Installation
Before putting your new water heater completely back into service, confirm all aspects are functioning safely and properly:
- Pressure Check
With the cold inlet valve turned back on, check all water fittings and pipe runs for leaks throughout the system. Repair any dripping connections. - Power Up Electric Units
Restore electrical supply to electric models at the breaker panel and verify the electrical control circuit powers on. - Inspect Burner Operation (Gas heaters)
Examine the pilot light flame and main burner ignition when turning gas supply back on. Consult manual for proper flame appearance. - Check Valve Positions
Ensure the T&P valve lever is in the closed position not allowing discharge until required for over-pressure. - Flush/Purge Air from Lines
Open nearby hot water faucets and shower heads to purge air pockets from the system until a steady stream flows. Let run to also flush sediment from pipes. - Compare Temperatures
Allow the tank to fully reheat overnight, then check temperatures at faucets to confirm the new heater reaches and maintains the desired level, typically 120°F.
Assuming all checks out, the project is complete! Give yourself a pat on the back. Just be sure to follow the maintenance tips below to keep your water heater running optimally for years to come.
Ongoing Water Heater Maintenance
While modern water heaters are very reliable and low maintenance, some periodic inspection and care is required to prevent premature failures.
- Flush the Tank – Annually drain 1-2 gallons water to purge any mineral sediment collecting at the bottom of the tank. Impurities settling in the tank will accelerate corrosion.
- Inspect Anode Rod – This sacrificial metal rod protects the tank from corrosion. Remove and examine every 2-4 years, replacing if significantly worn down.
- Check Valves and Fittings – Visually inspect pipes, water connections, and the T&P valve for any signs of drips or leaks. Address any issues immediately to prevent property damage.
- Clean Filters – For tankless heaters, clean/replace inlet water filters annually to maintain optimal flow.
- Check Venting – Ensure exhaust flue pipes remain properly attached and intact. Clear any potential obstructions around outdoor vents.
- Review Energy Use – Monitor electrical or gas energy consumption monthly for unexpected spikes that may indicate problems.
Following this preventative maintenance schedule and addressing any abnormalities promptly will maximize operational lifespans. Some systems last 10-15 years with proper care.
Conclusion
Upgrading your outdated or inadequate water heating system is now clearly a very approachable DIY project armed with this step-by-step guide. The process does involve moderately advanced plumbing and electrical skills but pays dividends through energy savings and always available hot water.
While each install location will have its own unique requirements, the information covered here should set you up for success when installing a common residential-grade water heater. As with any major home project, exercise caution and seek assistance from qualified pros if any complex connections or adjustments arise. Otherwise, tackle this worthwhile upgrade yourself and enjoy hot showers for years to come!