Understanding How Hot Water Heaters Work

Hot water heaters do one thing well: they heat water for bathing and washing. Until they were invented, everyone had to spend hours and hours heating water in giant pots on the stove just to take a single bath, and most families would take turns sharing the same tub because nobody wanted to empty the tub and reheat a ton of water for the next person to bathe. Some elderly people would avoid bathing because of the effort needed to bring that much water from a well to the stove and then into a tub.

Now, you have it pretty good. Whenever you want a hot shower, you can just turn on the faucet. Yet, how much do you know about the modern appliance known as the hot water heater? A contractor could probably tell you all of the following, and then some. 

There Are Different Types of Water Heaters

It is not just the gas-fueled or electric-powered heaters here. There are traditional tank heaters and tankless heaters. Tank heaters have a range of sizes for varying gallon amounts from 40 gallons to 120 gallons, depending on the size you already have in your home. The tankless heaters do not hold water at all. They heat water on demand as the water goes through the appliance and moves on its way up to your showers, sinks, dishwasher, and/or laundry washer. Knowing which will work best for your living situation is all part of the decision regarding what to buy, what to install, and what, if anything, you want to replace your current appliance with. 

How They Work

Water is sent into the water heater. In a tank heater, the tank is filled up with water, and the tank heater kicks on and heats the water to 100–130 degrees, depending on where you set the temperature on the water heater. It holds the hot water until you need it, and then the water goes up to the opened faucet. With a tankless heater, water is pulled into the appliance, heated rapidly, and sent right back out without holding a drop.

Tank Water Heaters Have to Be "Bled" Annually to Remove Sediment

Tank water heaters collect mineral and rust sediment on the bottoms of the tanks. This is perfectly normal, and it is expected that homeowners will "bleed" the tanks annually. This process involves opening a valve on the bottom edge of the tank and letting the tank drain completely. You will notice that the water is not clear and is a funky color. This means that there is sediment present, and you are doing exactly what you need to do to get rid of it. (Tankless heaters do not need this maintenance procedure at all.)

For more information about hot water heaters, reach out to a plumbing contractor.


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