“Reset” means two different things depending on whether your Rheem is electric or gas. On an electric unit it’s the red high-temperature cutoff button, the ECO, sitting on the upper thermostat behind the access panel, and it only gets pressed with the breaker off, after a tech has found why it tripped. On a gas unit there’s no reset button like that. What people call resetting is relighting the pilot or restarting the burner using the steps printed on the heater itself. The bigger point: a tripped ECO, or a pilot that keeps going out, means something is wrong underneath, and resetting won’t fix that.
Electric: the reset is the ECO, and the breaker comes off first
The reset button on an electric water heater is a safety switch called the ECO, short for emergency cut-off, also called the high-limit. It’s a small red button built into the upper thermostat, hidden behind the upper access panel and a layer of insulation. It trips and kills power to the elements when the water climbs past a safe temperature. That’s the tank protecting you from scalding water and worse.
How do you know it tripped? On an electric heater a tripped ECO usually means no hot water at all, because it cuts both elements at once. If you’ve still got some warm water, you’re probably looking at a single failed element or a thermostat, not the ECO.
Here’s the part most people skip. The ECO didn’t trip for no reason. It tripped because the water actually got too hot. The usual causes are a thermostat set way too high, a thermostat that’s failed and won’t shut the element off, or an element that’s shorted and heating nonstop. Rheem’s manual says a qualified tech has to find and fix that cause before the heater goes back in service. So don’t press the reset just to get hot water back. Until the fault is fixed, the water can get hot enough to scald. Replacing a thermostat or an element means testing live circuits and draining the tank, so that’s where I’d have you call.
Once the fault is fixed, the tech resets the ECO as part of the repair. That happens with the breaker off, because there’s 240 volts behind that panel and the ECO sits right next to live terminals.
Gas: there’s no reset button the same way
A gas Rheem doesn’t have that red ECO button. When people say they want to reset a gas water heater, they almost always mean the pilot went out and they need to relight it, or the burner quit and they want to restart it.
Don’t guess at the sequence. Rheem prints the lighting instructions right on the unit, usually on a label by the gas control valve, and the steps differ between an older standing pilot and a newer push-button igniter model. Follow that label. One thing it will tell you that’s worth repeating: turn the gas control to off and wait several minutes before you try to relight, so any gas can clear. Don’t shortcut that wait.
If the pilot lights but drops out as soon as you let go, or it keeps going out over and over, that’s usually the thermocouple or flame sensor not holding the gas valve open. Cleaning or replacing that is a pro job on a gas appliance. And if you ever smell gas, don’t fiddle with anything. Leave, and call 911 and PG&E at 1-800-743-5000 from a safe distance.
When one reset turns into a pattern
Relighting a gas pilot that blew out once is normal. Relighting the same heater again and again isn’t, and neither is a tripped ECO, even once. On electric that points at a thermostat or element. On gas it points at the thermocouple, the gas valve, or a venting problem. None of those get better by hitting reset one more time, and a couple of them are the kind of thing you don’t want to ignore. If the heater is old enough that replacing it is on the table, here is how Rheem and Bradford White tanks compare.
When to call us
If the breaker’s on and you still have no hot water, or the ECO has tripped, or a gas pilot won’t stay lit, that’s our cue. We cover the whole Bay Area and can usually get out same or next-day. Book at adriumservice.com or give us a call. We’ll find out why it tripped instead of just resetting it and walking away. I stand behind the work, even when I’m not the one knocking on your door.