

This guide provides comprehensive, step-by-step instructions for safely removing a failed or old water heater expansion tank and installing a new one. The process involves isolating the water heater from power and water supplies, relieving system pressure, removing the old tank, correctly preparing and installing the new tank, and then safely restoring the system to full operation while checking for leaks.
Best for experienced DIYers and homeowners with some experience with basic plumbing knowledge and familiarity with power tools. Requires EASTMAN 3/4 in. IPS Gas Pressure Test Gauge 0-30 psi 45167 and Watts 3/4 in. x 3/4 in. Brass FPT x FPT Natural Gas Shutoff Valve VAGV075K and GE Advanced Silicone 2 Caulk 10.1 oz Window and Door Sealant Clear 2811092.
The first and most critical step is to make the work area safe. Go to your home's main electrical panel and locate the circuit breaker labeled for the 'Water Heater'. Flip this breaker to the 'OFF' position. If you have a gas water heater, turn the gas control dial on the unit to 'OFF' and close the manual gas shut-off valve on the supply pipe. Next, find the cold water pipe that enters the top of the water heater and turn the handle of the shut-off valve clockwise until it stops. This prevents new water from entering the tank while you work.
To prevent a large volume of water from spilling when you remove the tank, you must relieve the pressure in the system. Go to a nearby sink and open the hot water tap all the way. This will allow air to enter the system as it drains. Next, attach a standard garden hose to the drain valve located at the bottom of the water heater. Place the other end of the hose into a floor drain or a large bucket. Open the drain valve by turning its handle or using a flathead screwdriver. Let a few gallons of water drain out until the water level is below the expansion tank's connection point.
With a bucket positioned underneath to catch water, firmly grip the old expansion tank with one hand to support its full weight. Use a large pipe wrench or a pair of channel-lock pliers on the metal fitting at the base of the tank. Apply steady pressure counter-clockwise to break the seal. Once it's loosened, you should be able to continue unscrewing it by hand. As you remove it, tilt it carefully to drain the remaining water into the bucket. Be aware that a failed tank can be completely full of water and surprisingly heavy.
Before installing the new tank, you must ensure its internal air pressure matches your home's water pressure. Remove the plastic cap from the air valve on top of the new expansion tank. Use a standard tire pressure gauge to check the factory pre-charge. For this guide, we are assuming a target of 60 PSI. If the pressure is lower than 60 PSI, use a bicycle pump or an air compressor to add air until it reaches the correct pressure. If it's too high, gently press the pin in the center of the valve with a small screwdriver or the back of the gauge to release air. Re-check the pressure until it is accurate. Replace the valve cap once set.
Prepare the threads on the new expansion tank for a watertight seal. Take the roll of Teflon tape and, holding the tank with the threads facing you, wrap the tape clockwise around the threads. Use 3 to 4 full wraps, pulling the tape taut so it sinks into the grooves of the threads. Wrapping clockwise ensures the tape won't unwrap as you screw the tank in. Carefully lift the new tank and align its threads with the female fitting on the water pipe. Screw it in by hand for the first few turns to prevent cross-threading. Once it's hand-tight, use the pipe wrench to tighten it an additional 1 to 1.5 turns. The tank should feel snug and secure; do not overtighten.
Before restoring power, you must refill the tank and check for leaks. First, make sure the drain valve at the bottom of the water heater is fully closed and the garden hose is removed. Go back to the sink where you opened the hot water tap and close it. Return to the water heater and slowly open the cold water supply valve by turning it counter-clockwise. You will hear water rushing into the tank. While it fills, keep your eyes on the new expansion tank connection. Once the tank is full (the rushing sound will stop), thoroughly dry the connection with a paper towel and watch closely for any sign of moisture or dripping. If a leak appears, turn off the water and tighten the connection another quarter-turn.
With the tank full and leak-free, you can complete the job. Return to the electrical panel and flip the water heater's circuit breaker back to the 'ON' position. For a gas heater, follow the manufacturer's instructions printed on the tank to relight the pilot light and turn the gas control knob to 'ON'. To purge any remaining air from the system, go back to the hot water faucet you used earlier and open it fully. It will likely sputter and spit air for a minute. Let it run until a smooth, steady stream of water flows out, then turn it off. The water heater will now begin heating the water. Your expansion tank replacement is complete.
Solution: To avoid this issue: Be mindful of this warning and take appropriate precautions.
Solution: Pressure tanks should be checked for correct air pressure at least once a year, or every six months for best practice.
Solution: To avoid this issue: Be mindful of this warning and take appropriate precautions.
Solution: Correct pre-charge pressure is crucial for the proper operation and lifespan of the well pump.
Solution: To avoid this issue: Be mindful of this warning and take appropriate precautions.
Solution: Some manufacturers may suggest leaving the unit on, but turning it off is the universally safer method.
Solution: To avoid this issue: Be mindful of this warning and take appropriate precautions.
The most crucial steps are to completely shut off the power (gas or electricity) to your water heater and turn off the main water supply to your home. Additionally, relieve the pressure in the system by opening a hot water faucet and draining a small amount of water from the water heater's drain valve. This prevents scalding and flooding.
While some basic tools are common, a MaxxHaul 60 PSI Pressure Gauge is essential for correctly setting the new tank's pre-charge pressure to match your home's water pressure. You will also need two heavy-duty pipe wrenches (like KNIPEX or Crescent) to effectively loosen and tighten the tank connections without damaging pipes. Having these specific tools makes the job much easier and safer.
For a beginner, this project typically takes between 1 to 3 hours, assuming you have all the tools and materials ready. It is considered a beginner-friendly plumbing task as long as you meticulously follow the step-by-step instructions, especially regarding safety and proper pressure adjustment. Patience and preparation are key to a successful outcome.
The most common mistake is not correctly adjusting the new expansion tank's pre-charge air pressure to match your home's incoming water pressure. Use a pressure gauge to measure your home's cold water pressure and adjust the tank's air valve to match it before installation. An improperly charged tank won't function effectively and can lead to future issues.
You'll definitely need plumber's tape for sealing pipe threads, plenty of absorbent towels (like HDX or WYPALL) for spills, and a bucket (Unger 6 Gal. Heavy-Duty Plastic Bucket) to catch residual water. Doing it yourself can save you significantly on labor costs, potentially hundreds of dollars, as you only pay for materials and tool rentals if needed.
Most modern expansion tanks are designed to function effectively in various orientations – upright, sideways, or inverted – as long as they are properly supported. Always check the manufacturer's instructions for your specific tank model (e.g., Everbilt or Amtrol). If mounting horizontally or inverted, ensure it is securely braced to prevent stress on the piping.
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30 min | 7 Steps