Heating elements are how electric water heaters heat water. Two elements per tank — upper and lower. Either or both can fail. They're the #1 failure point on electric water heaters and the easiest DIY repair: 90 minutes, $30 part, $25 element wrench.
How heating elements work
An electric water heater has two screw-in (or flange-mounted) heating elements inside the tank. Each is wired through a thermostat. When the thermostat senses cold water, it closes a switch that sends 240V through the element's resistive coil; the coil heats up; water in contact with the coil heats up. When water reaches setpoint, the thermostat opens; element shuts off.
Upper and lower elements operate independently:
- Upper element — heats the top of the tank. When you draw hot water, this is what reheats the incoming column
- Lower element — heats the bottom. Maintains overall tank temperature
Most US electric water heaters have non-simultaneous wiring — only one element runs at a time. The upper takes priority when hot water is being drawn; the lower takes over once the upper portion is at setpoint.
Symptoms of a failed element
| Symptom | Likely failed element |
|---|---|
| No hot water at all | Upper element (or upper thermostat) |
| Hot water runs out fast (lukewarm after a short draw) | Lower element (or lower thermostat) |
| Water lukewarm at full draw, then cold | Lower element |
| Breaker trips repeatedly | Shorted element (water-side seal failed) |
How to test an element
- Shut off the breaker at the panel. Verify power is off with a non-contact voltage tester
- Remove access panel covering the suspected element (upper or lower; both are visible)
- Pull back insulation and plastic safety cover
- Disconnect the two wires from the element terminals (remember which goes where)
- Set multimeter to Ohms (resistance, Ω)
- Touch probes to the two element terminals
| Reading | Diagnosis |
|---|---|
| 10-30 ohms (typical 4500W element) | Element OK — problem is elsewhere (thermostat?) |
| 0 ohms (short) | Element shorted — replace |
| Infinite / OL (open) | Element burned out — replace |
Also test element-to-ground (one probe on terminal, one on tank). Any reading other than infinite/OL = element has a grounded short. Replace.
How to replace
Tools:
- Element wrench (1-1/2" socket or specialty element wrench, $20-30)
- Garden hose
- Multimeter
- Replacement element ($25-60 — match voltage, wattage, and type)
- Teflon tape (for gasket-style elements only) — most use a rubber O-ring instead
Steps:
- Shut off breaker; verify with voltage tester
- Shut off cold-water supply
- Open a hot tap somewhere in the house
- Connect hose to drain valve; route to floor drain or outside
- Drain the tank — for upper element, drain until water is below the upper element (~10-15 gallons). For lower element, drain fully
- Disconnect element wires (note their positions)
- Use the element wrench to unscrew counter-clockwise (often quite tight — use leverage)
- Remove old element; install new with new gasket/O-ring
- Tighten snugly — don't overtighten
- Reconnect wires
- Close drain valve; open cold-water supply
- Open the hot tap until water flows steadily (purges air — critical for electric tanks)
- Close hot tap. VERIFY THE TANK IS FULL. Powering an electric tank dry destroys elements within seconds
- Restore breaker
- Wait 60-90 minutes for water to heat
Picking the right element
| Spec | Standard |
|---|---|
| Voltage | 240V (US residential); 120V for small point-of-use |
| Wattage | 4500W typical; 3500-5500W range |
| Type | Screw-in (1" NPS thread) most common; flange-mount older units |
| Style | Standard, low-watt-density (longer, less scale buildup), high-efficiency |
For hard water, low-watt-density elements last longer because the coil runs cooler — slower scale formation.
Common issues during replacement
- Old element won't unscrew: use a longer breaker bar; apply penetrating oil to the threads; tap the wrench handle to break corrosion
- Element broke off in tank: needle-nose pliers to remove fragments; pieces in the tank are fine (settle to bottom and flush)
- New element leaks: O-ring not seated, or you used Teflon tape where an O-ring should be. Drain partially, redo
- Element burns out after replacement: tank wasn't fully refilled before power was restored. Replace again, refill properly
Element and warranty
Most water heater warranties cover elements under the "parts" warranty (5-10 years). DIY replacement during the warranty period voids it; use an authorized installer if inside warranty.
Related guides
- Thermostat — often paired with element replacement
- All water heater parts
- No hot water
- Hot water runs out fast
- Water heater repair
Bottom line
Heating element replacement is one of the easier water heater DIY jobs — 90 minutes, $30-60 part, basic tools. Test with a multimeter before replacing. Always refill the tank fully before restoring power; a dry element fails in seconds.