How to Install a Water Heater: A Step-by-Step Guide

Ever taken an unexpected icy shower? Most people don’t realize how much they rely on their water heater until it fails. A functioning water heater is essential for comfortable living, providing hot water for showers, dishwashing, laundry, and more. When your old water heater gives up the ghost, you’re faced with a significant problem that demands a quick and effective solution. Replacing it yourself can save you a considerable amount of money on professional installation costs, putting that cash back in your pocket.

However, installing a water heater is not a task to be taken lightly. It involves working with plumbing, gas lines (for gas heaters), and electricity, all of which can be dangerous if handled improperly. This guide provides a step-by-step walkthrough to help you safely and successfully install a new water heater, equipping you with the knowledge needed to complete the task efficiently and correctly. By understanding the proper procedures and safety precautions, you can regain your hot water and avoid the inconvenience and expense of relying on a plumber.

What key questions will this guide answer?

Do I need a permit to install a water heater myself?

Yes, in most jurisdictions, you will need a permit to install a water heater yourself. This is because water heater installation involves plumbing and often electrical or gas connections, all of which are regulated for safety and code compliance.

Permits exist to ensure that the installation meets local building codes and safety standards. These codes are in place to protect your home, your family, and the broader community from potential hazards like gas leaks, carbon monoxide poisoning, water damage, and electrical fires. Obtaining a permit typically involves submitting an application to your local building department, paying a fee, and scheduling an inspection after the installation is complete. The inspection verifies that the work was performed correctly and according to code. While some homeowners might be tempted to skip the permit process to save time and money, doing so can lead to serious consequences. If the installation is not up to code, it could create safety hazards and lead to denial of insurance claims in case of related damages. Furthermore, if you sell your home, unpermitted work can create significant complications and even legal issues during the transaction. Always check with your local building department to determine the specific permitting requirements in your area before starting any water heater installation project.

How do I properly drain the old water heater before removing it?

To safely drain your old water heater, first turn off the power or gas supply to the unit. Then, shut off the cold water supply valve located on the inlet pipe above the water heater. Attach a garden hose to the drain valve near the bottom of the tank and run the hose to a nearby drain or outside. Open a hot water faucet somewhere in the house to break the vacuum, and finally, open the drain valve to allow the tank to empty completely.

Draining the water heater completely is crucial for a few reasons. First, a full 40-80 gallon tank is incredibly heavy and difficult to move, posing a significant safety risk. Reducing the weight minimizes the chance of injury during removal. Second, residual water left inside can cause leaks and spills during the removal process, potentially damaging your floors or other surrounding areas. Draining also allows you to inspect the inside of the tank for sediment buildup, which can give you insight into whether regular flushing (draining a small amount periodically) was done and the condition of your plumbing. Before you begin the draining process, make sure you have a suitable place for the water to go. The amount of water will be significant, and you don’t want to inadvertently flood your basement or yard. If you’re draining into a sink or bathtub, be prepared for potential sediment to come through the hose, and have cleaning supplies handy. It’s also a good idea to check the drain valve itself for proper functioning before starting; old valves can sometimes be corroded and difficult to open or may leak. If the valve is stuck, carefully try loosening it with penetrating oil and a wrench, but avoid applying excessive force that could break it.

What type of pipe is best for connecting the new water heater?

The best type of pipe for connecting a new water heater is typically either copper, PEX (cross-linked polyethylene), or CPVC (chlorinated polyvinyl chloride). Each has advantages and disadvantages, and the “best” choice depends on your local plumbing codes, budget, skill level, and specific installation requirements.

Copper piping has long been a standard due to its durability and resistance to high temperatures. It can withstand the heat fluctuations around a water heater effectively. However, copper requires soldering, which demands skill and experience to create leak-proof joints. It is also generally the most expensive option. While traditionally used, copper can be susceptible to galvanic corrosion if directly connected to dissimilar metals, such as the nipples on the water heater (which are often galvanized steel). Dielectric unions are necessary to prevent this. PEX is a flexible plastic piping that’s become increasingly popular. It’s easy to install using crimp-ring or expansion fittings, requiring less skill than soldering copper. PEX is corrosion-resistant and can handle both hot and cold water. It’s also generally more affordable than copper. Make sure that the PEX you choose is rated for potable water and high-temperature use (suitable for water heaters). While easier to install, PEX might not be permitted by code in every location, and some plumbers prefer rigid piping for connections immediately around the water heater. CPVC is another rigid plastic pipe suitable for hot water applications. It’s similar to PVC but is specifically formulated to withstand higher temperatures. CPVC is joined using solvent cement, which is relatively easy to master. It’s more heat resistant than PEX but less flexible. Like PEX, you should check local plumbing codes to ensure CPVC is an approved material for water heater connections in your area.

How tight should the gas line connections be to prevent leaks?

Gas line connections should be tightened firmly but not excessively. The goal is to create a gas-tight seal without stripping the threads or damaging the fittings. The recommended practice is to tighten fittings to the manufacturer’s specified torque, if available. If torque specifications aren’t provided, tighten the fitting until it is snug, then apply an additional 1/4 to 1/2 turn. Always use two wrenches: one to hold the pipe steady and another to tighten the fitting.

When connecting gas lines, the most important thing is to ensure a leak-free seal. Overtightening can damage the threads on the pipe or the fitting, actually causing a leak. Undertightening, obviously, will also result in a leak. Using pipe joint compound or gas-rated Teflon tape is crucial to ensure a proper seal; apply it to the male threads only, being careful not to get any compound inside the pipe. After tightening the connection, always test for leaks using a leak detection solution (typically a soap and water mixture). Apply the solution liberally to all connections and watch for bubbles, which indicate a gas leak. If you detect a leak, carefully tighten the connection slightly more and retest. If the leak persists, disassemble the connection, clean the threads, reapply pipe joint compound or Teflon tape, and reassemble, ensuring proper alignment. If, after several attempts, you cannot achieve a leak-free connection, it is best to consult a qualified plumber or gas technician. They have the expertise and tools to safely and effectively address any gas line issues. Never take shortcuts or guess when working with gas lines; your safety and the safety of your household depends on it.

How do I set the thermostat on the new water heater?

After your new water heater is installed and filled with water, setting the thermostat is crucial for efficient and safe operation. The ideal temperature setting is typically 120°F (49°C), which provides hot water while minimizing the risk of scalding and conserving energy. Locate the thermostat access panel(s) on the water heater, remove the insulation and plastic safety cover, and adjust the thermostat dial to your desired temperature. Replace the safety cover and insulation after setting the temperature.

To set the thermostat accurately, you’ll likely need a flathead screwdriver. Most water heaters have two thermostats, one near the top and one near the bottom. It’s important to set both thermostats to the same temperature for consistent heating throughout the tank. Some models feature a digital display that simplifies the process, allowing you to adjust the temperature with push buttons instead of a dial. Refer to your water heater’s manual for specific instructions, as thermostat locations and adjustment methods can vary slightly between models. Always exercise caution when working with electrical components. Turn off the power to the water heater at the circuit breaker before removing any access panels. After setting the temperature, wait several hours for the water to heat up fully before testing it. Use a thermometer to check the water temperature at a faucet, adjusting the thermostat as needed until you achieve the desired temperature of around 120°F. Periodically checking the temperature ensures that the water heater is functioning correctly and efficiently.

What size expansion tank do I need for my water heater?

The size of your expansion tank is determined by your water heater’s capacity and your local water pressure. A common rule of thumb is to use a 2-gallon expansion tank for a 40 or 50-gallon water heater when the water pressure is below 80 PSI. If your water heater is larger or your water pressure is higher, you’ll need a larger tank.

To accurately size your expansion tank, you need to know your water heater’s tank volume (in gallons) and your incoming water pressure. Higher water pressure requires a larger expansion tank because the water expands more when heated. Most expansion tank manufacturers provide sizing charts that take these factors into account. These charts are usually available on the tank’s packaging or the manufacturer’s website. Failing to install the correct size expansion tank can lead to problems. An undersized tank will be quickly overwhelmed, leading to excessive pressure in your plumbing system, potentially causing leaks or even burst pipes. An oversized tank, while less problematic, is an unnecessary expense and takes up more space than needed. It is also recommended to check your local plumbing codes, as some jurisdictions may have specific requirements for expansion tank sizing. While calculating the exact size can be done with formulas, using a sizing chart is usually the easiest approach. These charts usually show the correct tank size for a range of water heater sizes and water pressures. For example:

How do I test the pressure relief valve after installation?

After installing a water heater, it’s crucial to test the pressure relief valve (PRV) to ensure it’s functioning correctly and can release excess pressure to prevent dangerous situations. Carefully lift the lever on the PRV and hold it open for a few seconds, observing if hot water flows out of the discharge pipe. Once you release the lever, the valve should snap closed firmly and the water flow should stop completely.

Testing the PRV is a simple but essential safety check. When you lift the lever, you’re manually opening the valve, simulating an over-pressure situation. The escaping hot water confirms that the valve’s internal mechanism is free and able to release pressure. Watch the discharge pipe closely. It should be directed safely away from people and property, typically extending to within a few inches of the floor. If the valve doesn’t release water when the lever is lifted, or if it continues to drip or leak after the lever is released, the valve is likely faulty and needs to be replaced immediately. Don’t be alarmed if a small amount of water continues to drip for a few moments after you release the lever. This is often just residual water draining from within the valve housing and the discharge pipe. However, any sustained dripping or constant leakage indicates a problem. Similarly, if the valve doesn’t reseal properly after testing, you could experience a continuous loss of hot water and potential energy waste. If the PRV fails the test, don’t attempt to repair it yourself unless you have considerable plumbing experience. Replacing a PRV is a relatively straightforward job for a qualified plumber, and it’s a small price to pay for the safety and longevity of your water heater and the safety of your home.

And there you have it! Installing a water heater might seem daunting at first, but hopefully, this guide has broken it down into manageable steps. Thanks so much for reading, and we truly hope this helped you get the job done. Feel free to stop by again soon for more helpful DIY tips and tricks!