Should You Turn Off The Gas Water Heater If The Water Is Off?


A water heater is an essential appliance in our everyday lives. We need it to do laundry, shower, wash dishes, and so on. It is turned on every day because we use it every day. But what about when we don’t use it, should we turn it off if the water is off?

If you will be leaving for a long period of time, then you should turn off your gas water heater. In the case that the water will be off only for a short time, then you don’t have to turn off your gas water heater. 

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There are various reasons you should turn your gas water heater off, but lack of water might not be one of them. To learn how to turn your gas water heater on and off, and whether it will cause a disaster while you’re on a vacation, keep reading. 

Should you turn off the gas water heater if the water is off?

Before pressure valves were used, homeowners were always advised to shut off the gas or electricity to a water heater which has the water cut off.  The reason for this was that once the water heater came on to heat up its reservoir, it would cause the water to expand, and that would cause it to pressurize to the point where the tank or a pipe would burst. For as long as the inlet valve was open to the circulation system, heating water would slowly expand into the city system and it wouldn’t build up the pressure.

Today that’s still good advice, as many overpressure or overtemperature valves unload into an inconvenient area. That can cause water damage, electrical problems, and so on. If fast freezing conditions are present at the discharge, the valve’s function might be damaged, which would result in the same over pressurization concerns that existed in the 1960s.

In case your water is off for a long period of time, it is best to shut off the water inlet at the tank to prevent siphoning or to shut off gas to the heater so you prevent undesired discharge, and potential over-pressurization. You can also leave as much hot water in the tank as you can to prevent freezing if your heating system becomes inoperable.

If your water will be off for a short period of time, it’s best to leave it turned on. Since the water heater works off water pressure to provide hot water, the tank pressure will be equal to your water pressure. Since there is no inlet water pressure, there will be no outlet water pressure. 

To keep your gas water heater healthy and prevent any disasters, drain your water heater to get rid of sediment buildup twice a year. You should also check the water heater pressure relief valve once a year. Keep in mind that gas water heaters should be replaced every 10 years.

Should you turn off the gas water heater when on vacation?

Standard gas water heaters are usually very easily switched to a “vacation” mode. Set the dial at the bottom of the appliance to vacation setting. Another thing you can do is shut off the cold water supply to the water heater to limit damage in the event of a leak from the tank.

When you get back from your vacation, do a visual inspection of the appliance. Then open the cold water supply and set the dial back to warm setting to the largest square for this option. Usually, a gas heater will take a little over an hour to heat the water in the tank to the set temperature.

You will have to turn your gas water heater back on when you come home from your vacation. To do this, close all faucets and valves and turn on cold water. Then, light the pilot light and switch the gas valve to On.

In the case you’ve been trying to turn it on for a while, but you can’t, there might be a problem.

Here are some of the most common problems that could prevent your water heater from working properly. 

Mineral buildup

As time goes, calcium and magnesium can build up, which leads to what is known as hard water and impacts the water heater. This is called mineral buildup.

Failure to ignite

If your water heater fails to ignite, the gas supply could be low or the gas valve or water valves are not completely opened. In case your water heater is still not igniting after you’ve opened the gas and water valves, the problem could lie with a failed ignition pack. It is best to leave this to the professionals.

Constant overdrive

It is possible that your water heater is not capable of satisfying the constant need for hot water in your household. In this case, it should probably be upgraded, or you should consider adding another unit. 

Flame failure

The most common cause of flame failure is an electrical or gas pressure problem. Some other causes of this problem include low levels of propane, regulator failure, venting, combustion issues, or an inadequate gas line.

How do you shut the water off to your gas water heater?

Turn off the water heater valve.

To turn off your water heater valve, check the front of the tank and you will notice a red or black button. These buttons are sometimes hidden behind insulating materials, and you have to pull it off to reveal the button. Turn the switch from the “on” position to the “off” position.

When you turn the water heater, the pilot will stop working, and the burner will stop heating. 

Turn off the line that supplies gas.

Make sure to turn off the gas line valve, which is located on the gas line close to the heater. Turn the lever until it is vertical to the gas line. 

In case you can’t find a valve, trace the gas line until you find a handle that serves as the switch. It is usually very easy to locate a gas line, so you won’t have to search for too long. 

Shut off the water

Turn off the water heater and wait 12 hours for it to cool down. To drain your tank, put a bucket under the pressure relief valve so that water goes directly into the bucket. Open the relief valve to let the steam out and then gently release the lever. Attach a hose to the drain valve placed right at the bottom. Pull it to the particular spot you want to drain the water, which should be on a higher elevation than the position of the water tank. For example, you could drain the water in your garden. 

Next, turn off the cold water valve and turn on the hot water faucets to let the water run out. Make sure you keep the drain valve open until all the water runs out and then close it. 

Lastly, turn off all the open faucets in the house. In case your water doesn’t drain, it could be that mineral deposits have blocked the drainage channels. To get rid of them, shut off the valve and then pull off the hose to clear out all deposits. Attach the hose once again and turn on the valve.

Reasons for turning a gas water heater off

If you will be away for a long period of time, it is best to turn your gas water heater off. Even though it is highly unlikely that your water heater will cause a disaster, the risk increases with the length of your absence. 

If you smell gas, there could be a potential gas leak from your water heater. Natural gas doesn’t have a smell, but utility companies include an additive that helps consumers easily detect a gas leak, which smells like rotten eggs. If you leave the gas leak unattended, it could cause fire and explosion. If the gas smell is very strong, you should leave your home immediately and call the gas utility company. 

It is much less dangerous if you only faintly smell a gas leak. In this case, it would be a good idea to shut off the gas to flame-operated appliances, as well as your gas water heater. 

To turn off your gas water heater in the event of a gas leak, clear the area around your water heater so you have access to the gas pipe and shut-off valve. 

Find the gas pipe that fills gas into the water heater, as well as the shut-off valve. Keep in mind that the valve is placed along the pipe run itself, and not on the control box mounted on the water heater. In most cases, the valve will be a lever or a knob placed a few feet away from the water heater control box.

Next, turn the handle of the shut-off valve a quarter turn until it stops. If it is turned off, the handle should be at a 90-degree angle to the pathway of the pipe itself.

Lastly, immediately call the gas company to investigate the source of the leak and repair it. This should be a free service from the gas utility company.

Final Thoughts

So the question comes to this. How long will you be gone from your home and how long will the water be turned off? After you answer those questions you will know if you should turn the gas water heater off.

If you will be leaving for a long period of time, then you should turn off your gas water heater. In the case that the water will be off only for a short time, then you don’t have to turn off your gas water heater. 

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