What Happens If You Keep Resetting Your Water Heater? Risks, Fixes, and Safe Steps

When the hot water dies and that red button brings it back, it’s tempting to push it again and again. But if your water heater keeps tripping, the reset is screaming, “Something’s wrong.” Keep resetting and you risk scalding, electrical damage, gas hazards, and a voided warranty. I’ll show you what repeated resets actually mean, how to do one safe reset, the quick checks you can do without tools, when to call a pro in New Zealand, and how to stop it happening again.

TL;DR: What Really Happens When You Keep Resetting It

Here’s the short, honest answer so you know what you’re dealing with.

• Repeated trips mean overheating or a fault. The reset is a safety cut-out, not a “boost” button.
• Pressing it over and over can hide dangerous problems: stuck thermostat, failed element, wiring fault, sediment causing “dry firing,” or a blocked flue on gas.
• Real risks: scalding, tank rupture, electrical fire, carbon monoxide (gas), and insurance issues if you ignore a known fault.
• Do one safe reset after basic checks. If it trips again, stop. Power off and call a licensed electrician or gasfitter.
• In New Zealand, storage must be 60°C minimum to prevent Legionella and delivered at max ~55°C at taps via a tempering valve (NZBC G12/AS1). Don’t bypass safety gear.

Step-by-Step: Safe Reset and Checks (Electric and Gas)

These steps are for a typical household cylinder. If you smell gas, see soot, hear boiling, or the cylinder is leaking, skip straight to turning it off and calling a pro.

Before you touch anything

• Know your type: electric storage cylinder vs gas storage/instant. The red reset (ECO/Hi-Limit) is usually on electric cylinders under the top cover.
• Safety first: water + electricity + hot metal is not forgiving. Don’t remove covers unless the power is off.

Basic checks you can do without tools

1. Listen and look: Is the cylinder hissing like a kettle, or popping and crackling? That can be sediment burning on elements.
2. Feel the outlet pipe (carefully, brief touch). Scalding hot pipes with no mixing at taps can signal a stuck thermostat.
3. Check the switchboard: has the hot water breaker or RCD tripped? If yes, there may be a ground fault or short.
4. Look at the TPR valve discharge pipe: is it dribbling constantly? Occasional drips while heating are normal; a steady flow can be a fault.
5. Check for leaks around the cylinder base and element covers. Any dampness? Stop and call a pro.

How to do one safe reset (electric storage)

1. Turn off power at the circuit breaker or isolator. Confirm the cylinder is not heating (silence helps).
2. Remove the upper element/thermostat cover (usually a small cover plate). If you see charred wires or burnt smell, stop.
3. Press the red reset (ECO/high-limit). It should click once. Don’t force it.
4. Replace the cover securely. Turn power on at the breaker.
5. Wait. Hot water can take 30-90 minutes to improve; full recovery may take several hours depending on cylinder size.
6. If it trips again the same day or within a few heat cycles, stop resetting. Power off and call a licensed electrician.

Reset guidance for gas units

• Gas storage with pilot: relight per the manufacturer’s instructions once. If the pilot won’t hold, the thermocouple or gas control may be faulty. Don’t keep trying.
• Modern gas units with electronic reset: power cycle once. If it locks out again (flashing code), note the code and call a licensed gasfitter.
• If you smell gas, see soot, or suspect poor flue draft, turn gas off at the isolation valve and ventilate. Call a gasfitter. Don’t reset.

When to stop immediately

• Any burning smell, melted insulation, or scorched terminal.
• Boiling/rumbling sounds that don’t stop.
• TPR valve discharging hot water continuously.
• Wet element covers or visible leaks.
• Repeat tripping after a single reset.

NZ compliance notes (so you’re not fighting the system)

• Storage at ≥60°C is required to prevent Legionella. Delivery to hand basins, showers, baths must be tempered to ≤50-55°C (NZBC G12/AS1 and Acceptable Solutions).
• Electrical work on fixed wiring must be done by a licensed electrician. Gasfitting by a licensed gasfitter. You can press a reset and check your breaker; don’t rewire or replace thermostats yourself.

Real-World Scenarios: What Repeated Resets Usually Mean

Here’s what I see on callouts around Otago-and what the symptoms are telling you.

• Stuck thermostat (electric): Water is scalding hot at taps, pipes are too hot to touch, and the cylinder occasionally “kettles.” The reset trips to stop a boil-over. Dangerous because it can create overpressure and scald risk.
• Failed element (short-to-earth): Breaker or RCD trips, especially when heating starts. Resetting the hi-limit won’t help because the fault is in the element wiring.
• Sediment build-up (electric): Popping/crackling noises. Elements overheat locally-hi-limit trips. Common after years on hard water or if the cylinder hasn’t been serviced.
• Loose or burnt wiring at the thermostat/element: You may see darkened insulation under the cover. Heat builds at the terminal and trips the hi-limit. Fire risk-don’t reset and walk away.
• Thermostat mis-set or faulty tempering valve: Water at taps is much hotter than usual even when the cylinder seems normal. A bad tempering valve lets storage-level heat reach your taps. Resetting won’t fix it.
• Gas units: flame rollout or blocked flue: Sooting, scorch marks, or repeated lockouts. This is a CO hazard. Resetting can push your luck-get a gasfitter.
• Intermittent supply issues: Power dips can be the straw that breaks a tired thermostat. If resets coincide with storms or grid events but then keep happening, your control gear is likely on the way out.

Think of the reset as your smoke alarm. If it chirps once, fine-replace the battery. If it keeps screaming, you don’t tape it over.

Why the urgency? Because heat, pressure, and electricity can fail fast. The hi-limit is designed to trip once in a blue moon. If it’s your weekly ritual, there’s a fault that wants attention.

One more risk folks don’t expect: scald time. At 60°C, a child can get a serious burn in about one second. At 55°C, it’s around 30 seconds. NZ rules aim to keep the taps at or below 50-55°C with a tempering valve while the cylinder itself holds 60°C+ to stop bacteria.

Sources you can look up: NZ Building Code G12/AS1 (hot water), Ministry of Health guidance on Legionella, and burn time data published by medical associations.

Checklists, Rules of Thumb, and Next Steps (So You Don’t Guess)

Use these quick guides to decide what to do today and how to prevent future trips.

One-and-done reset rule

• Reset once per incident, max once in 24 hours.
• If it trips again, stop, power off, and book a pro.

Do-not-ignore list

• TPR valve discharging continuously (not just a few drips while heating).
• Burnt smell, discoloured wiring, melted covers.
• Water leaks around the cylinder or from the element covers.
• Sooting or scorch marks on gas units.
• RCD/breaker trips tied to heating cycles.

Quick DIY checks (safe, no tools)

• Switchboard: note if HWC breaker or RCD is tripping. Photograph it for the electrician.
• TPR pipe: check if it’s dry when not heating, occasional drips during heating are normal.
• Tap temperature: if it suddenly jumps hotter, suspect a thermostat or tempering valve issue.
• Sounds: popping/kettling suggests sediment; a gentle hum during heat-up is normal.

When you can try a simple fix

• Power flick: If a brief outage scrambled a control board (some modern systems), one power cycle can clear it. If it reoccurs, get it checked.
• Sediment flush: If you’re confident and the cylinder has a proper drain and isolation valves, a controlled flush can help. Still wise to have a plumber handle it to avoid stuck valves.

Who to call (NZ)

• Electric storage cylinder: Licensed electrician for thermostat/element/wiring faults. Plumber for valves, leaks, and cylinder work.
• Gas storage/instant: Licensed gasfitter for anything beyond relighting once per the manual.

Cost expectations (ballpark, NZ-varies by region)

• Thermostat replacement: moderate cost plus callout; often under the price of a new element.
• Element replacement: moderate; add cylinder drain time if needed.
• Tempering valve replacement: moderate; critical for scald protection.
• Gas diagnosis/repair: varies with parts (thermocouple/control board/flue work).

Preventive maintenance checklist (annual or biannual)

• Test TPR valve briefly (lift and release) if the manufacturer allows it and the discharge terminates safely. If it dribbles afterward, get it serviced.
• Have a pro check wiring tightness at elements/thermostats.
• Confirm delivery temp at a basin is ~50-55°C and storage ≥60°C.
• Ask about sediment flushing if your area has hard water.
• For gas units, have the flue draft checked and the burner serviced.

Simple decision tree

• If there’s a burning smell, leak, or continuous TPR discharge → turn power/gas off → call a pro.
• If the breaker or RCD trips when heating → don’t reset repeatedly → call electrician.
• If water at taps is now scalding hot → suspect thermostat/tempering valve → call electrician/plumber.
• If the unit locks out after you relight/reset a gas unit → note error code → call gasfitter.
• If it was a one-off after a power cut and doesn’t repeat → monitor, consider a service if it happens again.

Hard no’s

• Don’t bypass the hi-limit by taping the water heater reset button down.
• Don’t turn the thermostat below 60°C storage to “stop trips.” That invites Legionella.
• Don’t cap or block the TPR discharge pipe.
• Don’t work live or remove covers with power on.

If you’re renting: Document the fault with photos/video, send a written note to your landlord/property manager, and don’t keep resetting. You’re responsible for using it safely; they’re responsible for repairs.

If you own an older cylinder: If it’s 12-20 years old and needing frequent resets, weigh repair vs replacement. Newer cylinders can be more efficient and safer, and a fresh tempering valve is cheap insurance.

Mini‑FAQ: Fast Answers to Common Follow‑ups

Why does the reset trip in the first place?
It’s a thermal safety cut-out (ECO). When water gets too hot or a component overheats, it opens the circuit to stop heating. It’s there to prevent boiling and damage.

Is it safe to reset the button every time it trips?
No. A single reset after basic checks is fine. Repeated trips mean a fault that can escalate to scalds, electrical fire, or tank damage.

Can I just turn the thermostat down?
Don’t set storage below 60°C in NZ. That’s the line against Legionella bacteria. If you’re getting scalding at taps, fix the tempering valve or thermostat, not the storage temperature.

How do I know if my tempering valve is bad?
Sudden swings hotter/colder at taps, or hotter-than-usual water even at the same mixer setting. A plumber can test and replace it quickly.

What if my breaker (not the hi-limit) trips?
Breakers and RCDs trip for electrical faults like shorts or earth leakage. That points to an element or wiring issue. Call an electrician.

Could sediment be the only cause?
Sometimes. Sediment makes elements run hotter and can trigger the hi-limit. But you still want a pro to inspect, as the thermostat may have been stressed.

Is it legal for me to replace the thermostat myself?
In NZ, work on fixed wiring must be done by a licensed electrician. That includes thermostat and element connections.

Gas unit keeps locking out-can I try more than one reset?
One attempt per the manual is fine. Repeat lockouts often mean flame, draft, or sensor issues. Call a gasfitter, especially if you see soot.

Will insurance cover damage if I kept resetting?
Insurers can ask whether you ignored a known fault. Repeatedly resetting a safety device may complicate claims.

How hot should my taps be?
About 50-55°C at the outlet. A plumber can verify and adjust the tempering valve.

How often should a water heater be serviced?
Every 1-2 years is sensible: electrical checks, valve function, and sediment management. Gas units should have regular combustion checks.

What brand or model matters here?
The logic is the same across brands. A hi-limit trip is a hi-limit trip. The exact reset location and procedure vary; check your manual.

My cylinder is warm to the touch-normal?
Modern cylinders are insulated and should feel barely warm. If it’s hot to touch, the insulation jacket may be failing or the cylinder is overheating.

Could solar or heat pump systems cause trips?
Yes. Control faults, circulation issues, or backup element problems can all cause overheating. The fix still starts with a proper diagnosis.

Can the TPR valve cause tripping?
Indirectly. If a TPR sticks partly shut and pressure spikes, temperatures rise fast. But usually a tripping hi-limit is about the thermostat/element.

Is it ever just a glitch?
Power surges or one-off thermal events can happen. If it never happens again after a clean reset, you’re likely fine. Twice in a short span? Get it seen to.

Bottom line: use the reset the way it was designed-as a safety that lets you limp to a proper fix, not as a daily switch. If you’re in doubt, turn it off and book a pro. It’s faster, cheaper, and safer than rolling the dice with heat, pressure, and live wires.