To check a hot water heater element effectively, you'll need to use a multimeter to measure its electrical resistance and ensure it's not shorted. This process involves disconnecting power and safely accessing the element for testing.
Safety First: Essential Precautions
Before attempting any work on your water heater, always prioritize safety. Working with electricity and water can be dangerous if proper steps are not followed.
- Turn Off Power: Locate your home's main electrical panel and switch off the circuit breaker that supplies power to the water heater. It's wise to double-check with a non-contact voltage tester to ensure the power is truly off.
- Shut Off Water Supply: Close the cold-water inlet valve at the top of the water heater.
- Drain Some Water (Optional but Recommended): Draining a few gallons from the tank via the drain valve can help prevent spills and reduce pressure, especially if you plan to remove the element.
- Wear Protective Gear: Use insulated gloves and safety glasses.
Tools You'll Need
- Multimeter: Essential for measuring resistance (Ohms).
- Screwdriver: To remove access panels and element covers.
- Socket Wrench: To disconnect and potentially remove the heating element.
- Non-Contact Voltage Tester: To confirm power is off.
- Marker or Camera: To label wires for easy reattachment.
Step-by-Step Guide to Testing a Water Heater Element
Hot water heaters typically have two heating elements: an upper element and a lower element. The testing process is similar for both.
Step 1: Access the Elements
- Remove Access Panels: Use a screwdriver to remove the metal access panels, usually located on the side of the water heater, often secured by one or two screws.
- Remove Insulation and Protective Cover: Beneath the access panel, you'll find insulation and typically a plastic safety cover over the thermostat and heating element. Carefully remove these.
- Disconnect Wires: Take a picture or label the wires connected to the heating element terminals before disconnecting them. This ensures you can reattach them correctly. You'll usually find two main wires going to each element.
Step 2: Test for Continuity (Resistance)
This test determines if the element's internal coil is intact and can conduct electricity.
- Set Your Multimeter: Turn your multimeter dial to the Ohms (Ω) setting. If your multimeter has multiple Ohm ranges, start with a lower one, like 200 Ω, or select the auto-ranging feature.
- Measure Resistance: Place one probe of the multimeter on each of the two screw terminals of the upper heating element. Do not touch the probes to the tank or other metal parts during this test.
- Interpret the Reading:
- Good Element: A functional heating element will typically show a resistance reading between 5 and 25 Ohms. This range indicates the coil is intact and operational.
- Bad Element (Open Circuit): If the multimeter displays "OL" (over limit), "infinite," or a very high number, it means the element's coil is broken, and electricity cannot flow through it. The element is "open" and needs replacement.
- Bad Element (Shorted): A reading of 0 Ohms or very close to it could indicate a direct short within the element, meaning it's failed.
Step 3: Test for Ground Fault (Short to Ground)
This test checks if the element's coil is short-circuiting to the element's metal sheath or the water heater tank, which can cause circuit breakers to trip.
- Keep Multimeter on Ohms: Ensure your multimeter is still set to the Ohms (Ω) setting.
- Measure Between Terminal and Ground:
- Place one multimeter probe on one of the heating element's screw terminals.
- Place the other multimeter probe on the element's metal flange (where it screws into the tank) or directly on the exposed metal of the water heater tank.
- Interpret the Reading:
- Good Element: A functional element that is not shorted to ground will display "OL" (over limit), "infinite," or a very high resistance reading. This means there is no electrical path from the element's coil to its metal casing or the tank.
- Bad Element (Short to Ground): If you get any numerical reading (even a low one like 1, 2, or 100 Ohms) or 0 Ohms, it indicates a short circuit to ground. This element is faulty and must be replaced immediately.
Interpreting Your Multimeter Readings
Here's a quick summary of what your multimeter readings mean:
| Reading Type | Multimeter Display (Ohms - Ω) | Condition | Action Required |
|---|---|---|---|
| Resistance (Terminal to Terminal) | 5-25 Ω | Healthy, good continuity | Element is likely good. Check other components. |
| Resistance (Terminal to Terminal) | OL or Infinite | Open Circuit | Element coil is broken. Replace Element. |
| Resistance (Terminal to Terminal) | 0 Ω or near 0 Ω | Direct Short | Element is faulty. Replace Element. |
| Ground Fault (Terminal to Tank/Flange) | OL or Infinite | No Short to Ground | Element casing is insulated. |
| Ground Fault (Terminal to Tank/Flange) | Any numerical reading | Short to Ground | Element is shorted. Replace Element immediately. |
When to Replace an Element
You should replace a heating element if:
- Its resistance reading is outside the 5-25 Ohm range (0 Ohms or OL).
- It shows any resistance reading when testing for a short to ground.
While replacing a heating element can be a DIY task for experienced individuals, if you're uncomfortable with electrical work or plumbing, it's best to consult a qualified electrician or plumber.
Maintaining Your Water Heater
Regular maintenance, such as flushing your water heater annually to remove sediment, can prolong the life of your heating elements and the unit as a whole.
