Replacing or installing a gas water heater is a critical home maintenance task that requires attention to safety, precision, and adherence to manufacturer instructions. AO Smith, a leading manufacturer in residential and commercial water heating systems, emphasizes professional installation for gas units due to the inherent risks involved. This article provides a detailed, step-by-step overview of the installation process for AO Smith gas water heaters, based solely on the manufacturer’s published guidelines.
Understanding the Importance of Professional Installation
Gas water heater installation is inherently more complex and dangerous than electric water heater installation. AO Smith recommends that these systems be installed by local independent contractors who are trained and experienced in handling gas lines, venting, and safety protocols. The company explicitly states that professional installation ensures compliance with local codes, reduces the risk of gas leaks, and guarantees the system’s optimal performance and longevity.
For those who choose to attempt a do-it-yourself (DIY) installation, AO Smith provides a general outline in its support documentation. However, the company strongly advises users to consult a qualified professional, especially for unfamiliar or complex installations.
Preparing for the Installation
Before beginning the installation process, several preparatory steps must be completed. These include:
- Safety First: AO Smith emphasizes that working with gas, electricity, and hot water poses serious risks. If the installer is not confident in their ability to handle these hazards, professional assistance should be sought.
- Gather the Right Tools: Essential tools include wrenches, a garden hose, and a hand truck or dolly. The documentation highlights that the absence of the correct tools is a clear sign that professional installation is necessary.
- Review the Specifications: Before installation, it is important to check the water heater’s electrical and dimensional specifications to ensure compatibility with the existing infrastructure.
AO Smith also notes that the printed instructions provided with the water heater should be used as the primary reference, as the company’s online guides are intended to supplement—not replace—those instructions.
Step-by-Step Installation Process
Step 1: Place and Level the Water Heater
The first step in installing a new AO Smith gas water heater involves placing the unit on a stable base. A metal drain pan must be installed beneath the water heater. The drain pan should be at least 2 inches wider than the unit and no deeper than 1.75 inches. This ensures that any leaks or condensation can be contained and inspected easily.
The water heater should be positioned in the drain pan with enough clearance to allow for inspection beneath the unit.
Step 2: Install Heat Trap Fittings and Connect Water Lines
Heat trap fittings are essential for preventing heat loss and ensuring efficient operation. These fittings must be installed on the new water heater before connecting the hot and cold water lines. The connections should be made using 3/4-inch NPT threaded adapters to ensure a secure fit and prevent leaks.
AO Smith’s documentation includes visual examples of these steps, but it is important to note that the images are provided as general references and may not reflect the exact unit being installed.
Step 3: Install the Pressure Release Valve Discharge Line
The temperature and pressure (T&P) relief valve is a critical safety feature that must be installed correctly. The discharge pipe for this valve should have an interior diameter of 3/4 inch and should slope downward to ensure proper drainage. The end of the discharge pipe should be positioned between 1 and 6 inches from a drain or an external destination to prevent backflow and water accumulation.
This step is crucial for ensuring the system remains safe and functional over time.
Step 4: Connect the Gas Supply Lines
Connecting the gas supply lines requires careful handling and the use of appropriate tools. The gas lines must be securely connected to the water heater using two wrenches to break the union between the existing and new lines. The gas pipe should then be removed from the control valve and capped to prevent gas leaks during the installation process.
AO Smith reiterates that working with gas lines is a high-risk task and should only be performed by trained professionals.
Step-by-Step Uninstallation of the Old System
Before installing a new water heater, it is necessary to remove the old unit. The following steps outline the process for safely uninstalling a gas water heater:
Step 1: Run Water Until It’s Cool
To reduce the risk of scalding, the tank must be drained of hot water. This is done by turning on a hot water tap until the water runs cool. The process typically takes about 10 minutes.
Step 2: Turn Off the Water Heater and Gas Supply
The water heater must be turned off via the gas control valve, followed by the main gas supply valve. The gas lines should then be disconnected using two wrenches. After disconnecting the lines, the gas pipe should be capped and removed from the control valve.
Step 3: Shut Off the Water Supply
The hot and cold water supply lines must be turned off. A garden hose should be connected to the drain valve, and the other end should be directed to an outdoor area, a bucket, or a sink.
Step 4: Drain the Tank and Disconnect Lines
With the drain hose securely connected, the tank should be drained completely. To expedite the process, a hot water tap inside the home can be turned on. Once the tank is drained, the water and gas lines can be disconnected using a wrench.
Step 5: Remove the Gas Exhaust Pipe
After the tank is drained, the gas exhaust pipe should be removed from the draft hood. If necessary, the pipe should be propped or tied in place to accommodate the new installation. The old water heater can then be placed on a hand truck or dolly for removal.
Step 6: Remove the T&P Valve and Discharge Pipe
The T&P valve and discharge pipe should be disconnected. If the discharge pipe is in good condition, it can be reused for the new installation. However, the T&P valve should not be reused, as it is a safety-critical component that must be replaced with a new one.
Step 7: Disconnect the Water Lines
The water lines should be disconnected using a wrench. If compression fittings are used, they should be cut close to the water heater to facilitate connection to the new unit.
Step 8: Remove and Dispose of the Old Unit
Once all connections are removed, the old water heater can be placed on a hand truck or dolly and removed. Given the weight of these units, it is recommended to have assistance during this step.
Why Professional Installation Matters
AO Smith emphasizes that professional installation is the most reliable and safest option for gas water heater installation. Professionals have the training, experience, and tools necessary to complete the job efficiently and in compliance with local codes. This not only ensures the safety of the occupants but also minimizes the risk of system malfunctions or failures.
In addition, professional installers can provide valuable guidance on system selection, venting, and maintenance. This level of expertise is particularly important for gas water heaters, where even minor errors can lead to significant safety hazards.
Conclusion
AO Smith gas water heater installation involves a series of precise steps that must be followed carefully to ensure the system functions safely and efficiently. While the company provides general guidelines for DIY installation, it strongly recommends that these tasks be handled by qualified professionals. Gas water heaters require a high degree of technical knowledge and adherence to safety protocols, which makes professional installation the best option for most users.
By following the steps outlined in AO Smith’s installation guide and seeking professional assistance when necessary, users can ensure a successful and safe water heater installation. This not only protects the home and its occupants but also helps maintain the system’s performance and longevity.