A How-To for Inspecting Atmospheric Vent Gas Water Heaters

By Published On: August 31st, 2015Categories: Home Inspection Career Guide0 Comments
    Following these nine steps will help you properly inspect an atmospheric gas water heater:
        1. Examine the manufacturer’s plate to find the brand name and capacity of the water heater. Look at the serial number, which typically gives an indication of the year of manufacture.
        2. Take note of the location of water heater.  Fuel fired water heaters shall not be installed in a storage closet, bathroom or bedroom.  Water heaters located in a bedroom or bathroom shall be installed in a dedicated enclosure with solid, weather-stripped, self-close door and all combustion air taken from the exterior. If located in a garage or areas where flammables are stored, the ignition source of the water heater should be 18 inches above the floor unless it is FVIR, or the water heater is in a separate enclosed space accessible from outside the garage and no combustion air is taken from the garage. If the water heater is FVIR and located in a garage or carport and on the floor, a 3 inch minimum barrier should be installed in front of the unit.  Check inlet and outlet pipes, feeling them to confirm that cold water supply pipes are connected to the marked inlet and hot water distribution pipes are connected to the outlet.  If the pipes are reversed, document so in your inspection report.  Also, look for a water shut- off valve on the cold water side.
        3. On older water heaters that don’t have a sealed burner plate, turn down the thermostat (make a mental note of the current setting).  Remove both burner plates and inspect for rust, corrosion, sediment build-up, signs of leaking, and look to make sure the baffle has not collapsed onto the burner. You will also look for the same problems on newer units, but don’t remove the sealed burner plate; there is a little sight window that will allow you to look into the burner area of the unit (as of July 1, 2003, 30, 40, and 50-gallon, gas-fired water heaters built for sale in the United Sates must include features that will resist the ignition of flammable vapors outside of the unit).  Also look along the bottom of the tank for leaks.  If you find dripping water from the tank, try to determine if the tank is leaking or whether the drain valve or another connection is the cause of leaking. If the tank is leaking, recommend the tank be replaced.
        4. Turn up the thermostat so the flame kicks on. Evaluate the flame, which should burn mostly blue, or blue with some orange.
        5. Listen to the tank as the burner is firing.  A thumping or rumbling noise is an indication of sediment buildup inside the tank.
        6. Reset the thermostat to the same temperature that you found it.  Put back the burner plates (if inspecting an older unit).
        7. Check for gas leaks around the gas control valve and at unions and connections to gas lines near the water heater. Many home inspectors carry electronic testers that will detect the presence of natural gas. Please make sure you read the instructions on how to properly use the device and make sure you follow the proper calibration requirements. Please note, however, that using a gas detector is not required by most Standards of Practice.  If you find a gas leak with your detector, some inspectors carry a liquid soap solution to confirm there is an actual leak. Gas leaks should be reported as a safety hazard.  Also look for a gas shut off valve near the unit.  If there isn’t a shut off recommend one be installed.
        8. Inspect the relief valve and extension.  The relief valve should be mounted directly into the tank, either on top of the tank or at the side within 6 inches of the top. The valve should be free of corrosion.  Do not operate the relief valve during the inspection. Report a missing or improperly installed relief valve.  Missing or capped relief valves should be reported as a safety hazard.  If you find a leaking relief valve recommend a qualified plumber replace it.  Check that extensions are present and properly installed.  Allowed TPRV material is ZI Steel, CPVC, Hard-drawn CU, or listed TPRV drain in the UPC.  The extension should not be downsized as it goes down the tank. Check that the extension ends 6 inches or less (IRC) from the floor.  The UPC allows the extension to terminate 6 to 24 inches above ground or floor.  The extension should not be threaded or capped at the end.
        9. Inspect the venting.  First check for the presence of the draft hood. You can use a smoke stick and move it around the hood, watching to see which way the smoke leans.  If the smoke leans in toward the hood, that’s good.  But if the smoke leans outward from the hood, there may be a down drafting condition, indicating that carbon monoxide is being released from the hood. This should be reported as a safety hazard.  An inspection mirror can also be used to test for down drafting.  Hold the mirror close to the hood.  A fogged up mirror can indicate a drafting problem.  The unit should be operating when you do this test. Inspect the flue pipe for proper installation and note any rust or corrosion on the pipe.  Any holes in the flue pipe should be reported as a safety hazard.   Also check to make sure the flue pipe has a proper slope, a minimum of one quarter inch per foot or greater.

About the Author: Kristin Warner

Kristin is the Marketing Director at AHIT. She has authored content for numerous real estate brands, and managed corporate communications for a public real estate company. She is passionate about the home inspection and real estate industries, and loves digging into research to provide insights that empower home inspectors and real estate agents in their businesses.