Heating elements are the heat source on all electric water heaters — universal ¾" screw-in design across all major brands. When an element burns out (most common at year 7-12), the unit produces no hot water or lukewarm water depending on which element failed.
Standard element specs
| Wattage | Voltage | Healthy resistance | Application |
|---|---|---|---|
| 3500W | 240V | ~16-18 Ω | Older smaller tanks; some 30-gal |
| 4500W (standard) | 240V | ~10-16 Ω | Most residential 40-80 gal |
| 5500W (Heavy Duty) | 240V | ~9-11 Ω | Faster recovery; some 75/80-gal |
| 1400W | 120V | ~10 Ω | RV electric models (Atwood, Dometic, Suburban DE) |
| 1500W | 120V | ~38-42 Ω | Mini-tanks (Bosch Tronic, Reliance SOMS) |
Symptoms by which element failed
- Upper element failed: no hot water at all (upper is primary; controls power flow to lower)
- Lower element failed: lukewarm output; hot water runs out fast; upper section heats but lower stays cold
- Both failed: rare unless related cause (electrical surge, dry-fire damage)
Diagnostic test (multimeter)
- Power OFF at 240V breaker. Verify with voltage tester at the element terminals
- Remove access cover (upper or lower)
- Fold back insulation; remove plastic safety cover
- Disconnect ONE lead from the element (isolates it from circuit)
- Multimeter on Ω (resistance) — 200 Ω range or auto-range
- Touch probes to the two element terminals
- Compare reading to spec
Interpreting results
- OL or infinite: element failed open (burned out). Replace
- Near 0 Ω: element shorted internally. Replace
- Out of spec by 20%+: degraded element. Plan replacement
- Within spec: element healthy. Look elsewhere (thermostat, ECO, breaker)
Element-to-ground short test (critical)
With multimeter still on Ω, touch one probe to an element terminal and the other to the tank shell or ground bolt.
- Should read OL (open). Element is not shorted to ground
- Continuity present = shorted to sheath. Replace immediately — element shorted to ground trips breakers repeatedly and can damage contactor
High-watt density vs low-watt density
High-watt density (HWD) — standard
- Shorter element, more heat per square inch
- Faster recovery
- Scales faster in hard water (concentrated heat = faster mineral precipitation)
- Factory default on most brands
- $20-30
Low-watt density (LWD) — upgrade
- Longer element, more surface area, less localized heat
- Lasts much longer in hard water (less scaling)
- $25-35 (+$5-10 over HWD)
- Best for hard water installs at next replacement
Replacement procedure
- Power off at breaker; verify with voltage tester
- Drain tank to below the failed element\'s height (lower element = full drain; upper = drain ~half)
- Disconnect both leads (note positions)
- Use 1-1/16" element wrench to unscrew (often torqued tight; use cheater bar if needed)
- Inspect old element — scale, corrosion, burn marks
- Install new element with new gasket (always replace gasket)
- Hand-tight plus ¼-turn with wrench — do not overtighten
- Refill tank fully (open hot tap until steady stream — verify no air pocket)
- Restore power ONLY after tank confirmed full
Critical: never power up dry
Dry-fired elements burn out in seconds. The element must be submerged in water before energizing. Always:
- Verify tank fully refilled (hot tap runs steady, no air sputter)
- Then flip the breaker
- Dry-fire damage is NOT covered under warranty
Universal compatibility
4500W 240V screw-in elements are universal — Camco, Rheem, AO Smith, Bradford White, Marathon, all fit the same way. OEM elements are typically $25-40; Camco aftermarket at $15-25 fits and functions identically.
Bottom line
Element replacement is the most-common DIY electric water heater repair. Test before ordering — many "no hot water" calls are actually thermostat, ECO, or breaker. 4500W universal element fits any brand. Never dry-fire. Switch to low-watt density on hard-water installs.