No matter whether your home has a traditional water heater or an on-demand tankless unit, flushing it is one of the most important maintenance tasks. When it comes to flushing a water heater, the most common questions we get asked are how often it needs to be done and why it’s necessary. For this reason, today, you’ll learn everything you need to know about flushing your water heater to answer these questions and more
What Does Flushing a Water Heater Do?
Both traditional and tankless water heaters should always be flushed at least once a year, but the reasons for doing so are different for each type of unit. If you have a traditional unit with a hot water storage tank, flushing is necessary to remove sediment that builds up inside the tank. The water that comes into your home always contains at least some dissolved minerals. When the water is heated, some of these minerals solidify and form a hard sediment that settles down at the bottom of the tank.
Tankless water heaters don’t store any hot water, which means that sediment build-up isn’t an issue. However, some of the dissolved minerals in the water will still be left behind as it passes through the unit. This results in limescale slowly building up inside the water heater, which can damage its components and begin to clog the water lines. Flushing and cleaning a tankless unit helps to remove the limescale to ensure that your water heater continues to function properly.
How Do You Know When Your Water Heater Needs Flushing?
The general rule of thumb is that all water heaters should be flushed at least once a year. However, for homes that have hard water and don’t use a water softener, it is usually best to flush the unit every six months due to the higher concentration of dissolved minerals.
Virtually the entire state of California has quite hard water compared to much of the rest of the country, which is why we always recommend either installing a water softener or making sure to have your water heater flushed more frequently. While the San Jose area isn’t as bad as other parts of the state, the water is still classed as hard and has an average mineral concentration of around 130 parts per million.
If you haven’t had your traditional water heater flushed recently, there are some signs that can indicate that it is time to get it done. Specifically, if you notice that your water isn’t getting as hot or it takes much longer to reheat after using up all of the stored hot water, then it is a good idea to schedule an appointment to have your tank flushed.
Another sure sign that you need to have your tank flushed is if you hear some loud knocking or banging noises whenever the unit is heating. When the unit heats, it produces hot air bubbles that float up through the sediment. This disturbs the hard sediment and causes it to knock against the sides of the tank.
Why Flushing a Traditional Water Heater Is So Important
While flushing a tankless water heater is always a good idea, regularly flushing a traditional unit is far more important. This is because sediment build-up is the single biggest reason that traditional units fail or develop a leak in their tank.
With traditional gas units, the layer of sediment at the bottom of the tank basically acts as an insulator. The sediment absorbs much of the heat produced by the gas burner and prevents it from being transferred into the water. This leads to increased energy costs since the unit will need to run longer to heat the water fully. It also means that your recovery time, or the time it takes for the unit to reheat, will also be much longer.
All that being said, the biggest issue is that the sediment often results in hot spots forming at the bottom of the tank. These hot spots can weaken the metal tank and also speed up the rate of corrosion, which has the potential to cause the tank to develop a leak eventually.
Sediment build-up is also an issue with traditional electric water heaters. Whereas gas units have a large burner underneath the tank, electric units have two electric heating elements located inside the tank. One element is in the upper portion of the tank, and the other is near the bottom. If the sediment ever builds up to the point where it comes into contact with the lower heating element, it can easily damage the element and cause it to fail and need replacing.
How to Flush a Water Heater
Flushing a water heater is something that you can do on your own, but we generally wouldn’t recommend it. Instead, we recommend hiring a professional plumber to flush the tank for you as part of your annual water heater maintenance service.
Flushing a traditional water heater involves first shutting the unit off and leaving it off for at least a few hours or preferably overnight. This ensures that the water in the tank has time to cool so that there is no risk of scalding when the tank drains.
Once the water is sufficiently cooled, turn the cold water supply off so that no more water will flow into the tank. A garden hose is then attached to the drain valve at the bottom of the unit. Before opening the valve to drain the tank, it is first necessary to open up a hot water faucet somewhere in the building. This is important because, otherwise, a vacuum will form inside the tank and prevent it from draining if all of the plumbing fixtures are closed.
Once the tank finishes draining, turn the cold water supply back on so that water again flows into the tank to help flush out all of the sediment. The water is then left running until there is no sediment left and the water coming out of the unit is completely clear. Depending on how much sediment there is, it could take anywhere from 10 minutes to an hour or more before the tank is fully flushed.
If there is lots of sediment in the tank, it will often end up clogging the drain valve. When this happens, it is then necessary to clear the clog. Sometimes you can clean the clog easily, but other times the only way to clear it is to back-flush the unit by connecting the hose to another water fixture. There are also times when the drain valve can become so clogged that the only option is to replace it, which is another reason why it is always best to have a plumber flush your unit for you.
If you need your water heater flushed or any other plumbing service, you can trust the team at Plumbtree Plumbing & Rooter to help. We work on all brands and types of water heaters, and we can assist with repairs, maintenance and new equipment installation. We also specialize in drain cleaning and repair, rooting, hydro jetting and a full range of water, gas and sewer line services. For more information or to schedule any plumbing service in the San Jose area, contact Plumbtree Plumbing & Rooter today.