Installing a Draft Hood on a Gas Water Heater: A Complete Guide

Installing a draft hood on a gas water heater is an essential part of ensuring your system operates safely and efficiently.

A draft hood helps guide harmful combustion gases out of your home, preventing dangerous build-ups like carbon monoxide.

In this guide, we’ll take you through everything you need to know about draft hood installation, from understanding its function to troubleshooting common problems.

What Is a Draft Hood and How Does It Work?

A draft hood is an essential component of a gas water heater with an atmospheric venting system.

It is located at the top of the water heater and connects it to the venting system. The part serves to cool the combustion products, such as flue gases, and direct them safely to the venting system. This process ensures that harmful gases, like carbon monoxide, are vented outdoors rather than accumulating inside the home.

Additionally, the draft hood helps regulate the airflow by preventing backdrafts caused by pressure differences between indoor and outdoor air.

What You Need to Know About Atmospheric-Vent Gas Water Heaters

Gas water heaters powered by natural gas or propane require a venting system to expel combustion gases. Atmospheric-vent gas water heaters are the simplest and most affordable type, using a metal pipe and chimney to transfer combustion products (flue gases) outdoors, often vented through the roof.

Unlike power-vented systems, atmospheric-vent heaters rely on natural convection, where hot gases rise due to their lower density.

For optimal function, ensure that the vent has a vertical or upward slope to allow the exhaust gases to rise freely. Proper height and vertical section requirements are necessary for efficient gas flow and maintaining the exhaust gas temperature.

Draft Hood Installation: Step-by-Step Guide

Understand the Different Draft Hood Types

• Lock-in Type: This draft hood has slots that allow it to lock securely onto the water heater.
• Push-in Type: This type is secured using self-drilling screws (usually provided), typically 5/8″ long or shorter.

Preparing for Installation

Before starting the installation, gather the following tools:

• Pliers
• Drill
• Screwdriver
• Tape measure
• Sheet metal cutting tool

Securing the Draft Hood

• Place the draft hood on the top of the water heater.
• For a lock-in type, simply align the slots with the heater and lock the legs into place.
• For a push-in type, secure the draft hood with 3 evenly spaced self-drilling screws, ensuring they are tight but not overly tightened.
• Attach the vent pipe to the draft hood using a sheet metal screw. Ensure that the vent pipe’s diameter matches the draft hood size and is airtight to avoid leaks.

Connecting the Vent Pipe

The vent pipe should be no smaller than the draft hood’s diameter. It can be made of either single-wall or double-wall galvanized pipe, depending on the model. If using a double-wall pipe, it’s best to install a Type B connector. Make sure all connections are properly sealed and airtight to prevent flue gas leakage.

Follow Manufacturer’s Instructions

Always refer to the manufacturer’s instructions and local building codes to ensure proper installation. These guidelines ensure that your water heater operates safely and efficiently.

Testing the Draft Hood

To test whether the draft hood is functioning properly, perform a depressurization test:

1. Close all doors and windows in the house and turn on any fans (clothes dryer, range hood, bathroom fans, etc.).
2. Light a match and hold it near the draft hood.
3. If the flame or smoke is drawn into the draft hood, this indicates that the venting system is working correctly.
4. Alternatively, you can use a glass or mirror near the draft hood. If it fogs up, it means that flue gases are escaping into the house, which should be addressed immediately.

Common Problems and How to Solve Them

• Backdrafting: This occurs when the vent doesn’t expel gases effectively, causing them to flow back into the home. Ensure the vent has the proper slope and that the draft hood is installed correctly.
• Excessive Draft: A strong draft can create noise, sooting, or poor burner performance. Check that the vent system isn’t too short or overly sloped.
• Insufficient Air Supply: Proper combustion requires a steady supply of air, either from indoors or outdoors. Ensure the space around the water heater is adequately ventilated.

Do’s and Don’ts When Installing a Draft Hood

• Do use the draft hood designed specifically for your model.
• Don’t modify, cut, or change the draft hood during installation.
• Don’t block the draft hood or surrounding area.
• Don’t use vent pipes or materials other than those recommended by the manufacturer.
• Do follow all manufacturer instructions and local codes for installation.

Conclusion

Knowing the importance of installing a draft hood on a gas water heater is crucial for ensuring the safety and efficiency of your heating system. Installing a draft hood properly, by following the correct steps and troubleshooting any issues, helps you enjoy reliable performance while keeping harmful gases out of your home.

If you’re uncertain about any part of the installation process, it’s always best to consult a professional plumber who can guarantee that everything is done to code and safely.