Turn Off Water Heater? When It’s Smart — And When It’s Not

A water heater may run either on electric power or gas as fuel and for this reason, it may not be the wisest decision to leave it turned on because of the safety risk and cost implication. So, should you turn it off when not in use? There are several reasons why you would ask yourself this question, whether no one is at the house and you’d like to save some extra money, or going on a vacation and it would be pointless to leave the heater on for over three weeks without any use. There are times when you should switch it off. One of these scenarios is when you are draining the tank and there’s no water inside for heating. Turning it on would damage the boiler. The second scenario is very unlikely and that is a presence of pressure loss on the cold water side as compared to the heat-out pipe.

Cost-saving

More often than not it is the cost implication we try to bring down when we want to shut our water boiler off, but are there any significant savings? When you keep the water heater running it will continually heat the water whether or not you use it. The gas or electric bill will not cease to rise for an instant. Experts advise that even though the cost savings of turning the boiler off when, not in use is negligible, it is saving nonetheless. You should turn on the heater 30 minutes before you would want to use the hot water. This provides the boiler enough time to reach the optimum working conditions and heats the water for use. You could do this manually or use a timer preprogrammed to your routine, whether it is minutes before you wake up or just arrive from work to find your hot water waiting for you. What causes loss of money when operating any thermodynamic appliance is heat loss weather within the working mechanism or loss to the immediate surrounding. Heat is continually lost in the hot water inside the heater at an estimated 10%. So if you were to pay $30 on this cost then $3 has gone to waste. This is why turning it on only when in use increases the efficiency and money-saving in the long run. If you place your hand at the side of the boiler and feel as though the surface is warm, then just know you are putting your money in the bin. It would do you good to get the heater insulated by a professional to keep all that heat within the boiler and keep the water up to temperature. This will help cut down the cost of heating the water by 7% to 18% on average. It also helps keep the water warmer for longer without the need to turn on the boiler which means after the water is heated you could turn off the boiler and still receive hot water for a good while. These are short-term scenarios but what if you are going on a trip and won’t be home for a considerable amount of time? Should you leave it on? Most water heater companies in the recent past have integrated the vacation setting on the thermostat indicated by VAC. What this setting does is it reduces the running temperature from the normal 120 degrees Fahrenheit to allow a more cost-effective temperature of 50 degrees Fahrenheit. This temperature is friendlier to run and even though you’d be gone for a while, on your return, turning up the heater would be a breeze as it is not starting with totally cold water. Trying to start a boiler from cold may stress the mechanism but if it is in proper working condition it can handle it without much trouble. For those penny pinchers who wouldn’t dare spend more for what they didn’t use, it is practical to switch it off and switch it on 30 minutes to 1 hour before using it upon your return. If the cost implication ( though minor) doesn’t seem to bother you then it is perfectly safe to leave it running but at a temperature of between 40 degrees Fahrenheit to 50 degrees Fahrenheit. You can set this manually if you don’t have the VAC option and it will still lead to the same efficiency.

Risk factor

Before letting your boiler stay running for long periods, make sure the temperature and pressure relief valve work fine and that the boiler isn’t old and can withstand continuous stresses. If using a gas burner it is better to turn it completely off when going on a vacation. This is because a gas leak could develop while you are away leading to an explosion and you’d come back only to find your house level on the ground. Always call a professional to check on maintenance issues so that you have ease of mind that your boiler runs efficiently and is not in any way a hazard.

Frequently Asked Questions

Should I turn off my water heater when not in use?

For absences of 3 or more days, switching a gas heater to pilot mode or an electric heater to vacation mode saves energy without sacrificing convenience. For shorter breaks, the energy saved by turning off rarely exceeds the cost of reheating a full tank from cold.

Will turning off my water heater save money?

Yes, for extended absences. A gas tank heater consumes 3–5 therms per week in standby heat loss alone. Switching to pilot or full off for a 2-week vacation saves $3–$8 at typical gas rates — modest but worthwhile if you travel regularly.

How do I turn off an electric water heater safely?

Locate the dedicated circuit breaker for the water heater in your electrical panel and switch it to the off position. Leave the water supply on to maintain system pressure. To restart, simply switch the breaker back on and allow 1–2 hours for the water to fully reheat.

Is it bad to turn off a gas water heater completely?

No — turning a gas water heater fully off is safe and straightforward. Turn the gas valve to the “off” or “pilot” position and shut off the cold water supply if the unit will be drained. Relighting the pilot on return is the main extra step vs. leaving it on pilot.

What happens if I leave the water heater off for a long time?

For most units, extended shutdown causes no damage if water remains in the tank. In freezing climates, an unheated tank may freeze and crack if temperatures drop far enough — in that case, drain the tank before a long winter shutdown. Anode rod activity also slows when the heater is off, which is harmless.