Ask the Home Inspectors: A crash course in water heaters

By Gabe Semenza and Joe Hanselka
April 11, 2012 at 7:02 p.m.
Updated April 10, 2012 at 11:11 p.m.

You probably never give much thought to your water heater until you step into a cold shower or become forced to deal with leaks at or under the unit.

Like any equipment, however, the water heater has several components that must operate in unison to safely and efficiently do its job. This column will give you a general overview of ways to spot deficiencies within your water heater.

Although tankless and on-demand water heaters have grown in popularity, we find the vast majority of Crossroads residents still use the traditional tank-type units - those cylindrical vessels that often hold between 30 and 50 gallons. So, we will focus on those.

Within this category, we regularly inspect two varieties: Electric and gas-fired water heaters. Luckily, both share several common features.

Assuming you have hot water at all your indoor plumbing fixtures, the first step to ensure the unit otherwise works OK is to check for leaks. Examine the base of the unit for signs of moisture and rust, and then scan upward.

If you don't have a drain pan underneath the unit, it's best to install one. A pan should properly collect leaks and then drain the water to a place, often outside, that is visible and won't cause damage.

Next, check for leaking or corroded fittings at the incoming and outgoing water supply lines. Make sure a cold water shutoff valve is installed on the incoming line, which is usually labeled. Turn the shutoff valve to the right to ensure it's not frozen, and then return it to its original, or open, position.

If your cold water shutoff valve is frozen, you would struggle - or not be able - to stop the flow of water to the unit if you are forced to do so.

Next, ensure the water heater has a temperature pressure relief valve and associated 3/4-inch drain line - not to be confused with the drain valve located at the bottom of the tank. The temperature pressure relief valve and drain line are arguably the most crucial safety components of the water heater.

We often find these valves either on top of the tank or on the side. Either location is fine so long as it's installed within the top six inches of the tank, where the hottest water is stored.

When working properly, the temperature pressure relief valve releases water and pressure when the tank's water becomes overheated or excessively pressurized. Without this important valve, the water heater could explode in either scenario.

Because the valve is designed to release superheated water and pressure when needed, its drain line must extend to about six inches from the drain pan or to a similar distance from the ground outside. This way, the release of water and pressure likely will not cause damage or injury. These drain lines should drain by gravity and should never flow uphill at any point.

Water heater explosions are rare, but they do happen. So it's equally important to determine if your unit is properly located. This determination can become tricky and bogged down by lengthy code, however, especially if you have a gas-fired unit. If you're unsure whether your unit is properly located, call us or your plumber.

If your electric or gas-fired water heater is located in the garage, the unit should be a minimum of 18 inches off the floor - above where gas, oil and paint fumes settle.

While our inspection of water heaters delves much deeper than the items discussed here, we hope this quick overview arms you with some basic and helpful information.

Gabe Semenza, TREC Lic. No. 20,326, is owner of Semenza Inspections. Joe Hanselka, TREC Lic. No. 1,166, is owner of Crossroads Inspection Services, and Semenza's professional sponsor. If you have questions about inspections, contact the real estate inspectors at 361-676-1480 or 361-576-6429 respectively.



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