An electric water heater that’s gone cold, or runs out of hot water halfway through a shower, is usually not a dead water heater. It’s usually a dead heating element — a cheap part, held in by one wrench, that fails long before the tank does. Here’s how to tell, and what to buy.
Still running out fast with good elements? Check the dip tube.
Relief valve dripping after a heating cycle? That is usually thermal expansion — see expansion tanks.
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What the symptom tells you
A residential electric water heater usually has two elements — one near the top of the tank, one near the bottom — and they don’t run at the same time. That’s why the symptom points at which one failed:
- No hot water at all → typically the upper element (or the upper thermostat feeding it). The top element heats first; if it’s dead, nothing downstream happens.
- A little hot water, then cold — and it recovers slowly → typically the lower element. The top of the tank still heats, so you get a short supply, but the bulk of the tank never comes up.
That split is the most useful diagnostic in the whole job, and it costs nothing to observe.
Before you buy: match the element
Elements are not universal. Three things have to match, and all three are printed on the old element or on the heater’s data plate:
- Voltage — 240V is standard for residential; 120V exists on small point-of-use units. Mismatch here and it either won’t heat properly or will fail.
- Wattage — commonly 4500W or 5500W. Don’t upsize. A higher-wattage element draws more current than the circuit and wiring may be rated for.
- Mounting style — screw-in (threaded, by far the most common) or bolt-in (four bolts and a gasket). They are not interchangeable.
What to buy
- Rheem SP10552MH 240V/4500W screw-in element — the common residential replacement size and style. Confirm your own heater’s voltage, wattage, and that it’s screw-in before ordering.
- Camco 09883 water heater element wrench — you cannot do this job with a standard socket. The element takes a deep 1-1/2″ socket, and this is the cheap purpose-built version.
The order of operations that keeps you safe
An electric water heater is a 240-volt appliance sitting in a tank of water. Sequence matters:
- Kill the breaker — the dedicated double-pole breaker for the heater, not just the switch.
- Verify it’s dead with a non-contact tester or meter at the element terminals. Test your tester on a known-live circuit first.
- Shut the cold supply and open a hot faucet somewhere in the house to break the vacuum.
- Drain the tank below the element you’re replacing (hose on the drain valve). The lower element means draining nearly the whole tank.
- Swap the element — note the wiring, unscrew, replace the gasket with the new one, thread the new element in clean.
- ⚠️ Refill completely BEFORE restoring power. Energizing an element that isn’t submerged burns it out in seconds. Run a hot faucet until it flows steady with no air.
- Then restore the breaker.
Step 6 is the one that ruins the brand-new part. It’s also the one people skip because the job feels finished.
While the tank is drained
You’ve already done the hard part of the anode job — the tank is drained and the tools are out. If you don’t know when the anode rod was last checked, this is the cheapest moment you’ll ever get to look at it, and a spent anode is what turns a repairable heater into a replacement. Sediment flushing is worth doing now too, since the drain hose is already connected.
If the heater itself is near end of life, the honest math on repair-versus-replace is in what it costs to replace a water heater, and if you’re weighing formats, tank vs tankless.
When it isn’t the element
- The thermostat. Elements are switched by thermostats; a failed upper thermostat produces the same “no hot water” symptom. Elements can be tested for continuity with a meter — no continuity means a dead element, continuity means look at the thermostat.
- The high-limit (ECO) trip. If the red reset button on the upper thermostat has popped, something caused an overheat. Resetting it without finding out why just defers the problem.
- Sediment. A lower element buried in sediment overheats and fails early — and will do it again to the new one if you don’t flush.
Working through it symptom-first? See no hot water troubleshooting.
FAQ
How do I know which water heater element is bad?
No hot water at all usually points to the upper element or thermostat; a short burst of hot water followed by cold usually points to the lower element. Confirm with a continuity test at the element terminals with the power off.
Can I put in a higher-wattage element?
No. The wattage must match what the heater and its circuit are rated for. A higher-wattage element draws more current than the existing wiring and breaker were sized for.
Do I need a special wrench?
Yes — screw-in elements need a deep 1-1/2″ element wrench. A standard socket won’t clear the terminals, and prying at it damages the tank threads.
Related guides
- No hot water: troubleshooting
- Cost to replace a water heater
- Tank vs tankless
- Water heater thermostat replacement
Fix the 12 Most Common Plumbing Problems Yourself — Free Plumber’s Handbook — including how to tell if your water heater is about to fail
Step-by-step fixes for the 12 most common problems — and exactly when to call a pro. Free and instant, from a licensed plumber. Save hundreds on calls you didn’t need.