Kitchen and Dining

What is a Tankless Water Heater?

During the holiday season when your house is swarmed with houseguests, you’d need a nice hot shower to soothe your nerves. But before you can relax peacefully in your bathroom, you have to wait in line behind your cousins and in-laws. Then, when it’s finally your turn, the big tank runs out of hot water. You have to wait for it to fill up with enough hot water again. During times like these, a tankless water heater would be a blessing.

tankless water heater

Tankless water heaters, or demand-type or instantaneous water heaters, provide hot water only when it’s needed, instead of continually heating water stored in a tank. It doesn’t produce the energy losses associated with standard tankless heaters, thus conserving natural gas and money on bills. A tankless water heater looks like a box, about the size of a suitcase, and is usually mounted on the wall.

How It Works

To know how a tankless heater works, it’s important to understand how a standard tank heater operates. A traditional heater system heats water in a large tank. The tank continually heats water to maintain a constant temperature. In short, it keeps the water hot even when it’s not being used, and it’s called standby heat loss.

Tankless water heater works to prevent standby heat loss. You don’t need running water all the time, so it works to heat water only as you need it – that’s why it’s called a demand type water heater. This makes it more energy efficient.

When opening a hot water tap, such as a shower or faucet, or starting the washing machine or dishwasher, cold water travels through a pipe into the unit. The tankless water heater recognizes the need for hot water and starts the heating the water using either a gas burner or electric element. It calculates how much heat the burners must produce to deliver water at the desired temperature by identifying the temperature of the incoming water. As a result, it delivers hot water that’s just right to your liking. When you turn off the faucet, the tankless water heater also turns off.

To generate heat, a tankless water heater uses a powerful heat exchanger to raise the temperature. It’s a device that transfers heat from one source to another, and in this case, it transfers heat from the gas-fired burner or electric coils to the water that comes out of your faucet.

Usually, a tankless water heater can provide hot water at a rate of 2-5 gallons per minute. Gas-fired tankless water heaters can produce higher flow rates than electric ones. Also, even the largest, gas-fired models can’t supply enough hot water for simultaneous use inside a large household. For instance, when someone’s taking a bath, and another person is using the dishwasher, you may stretch tankless water to its limit. If you have a large home, you can install two or more tankless water heaters. You may also install separate tankless water heaters connected to your appliances that use a lot of hot water, such as your washing machine or dishwasher.

Types of Tankless Water Heaters

Tankless water systems come in three varieties: point-of-use water heaters, whole-house heaters, and hybrid heaters.

  • Point-of-use water heaters – small water heaters that are installed near an area, room, or appliance that needs hot water. Because it’s small, it can be installed under a cabinet or a closet and be placed closer to your outlet to avoid water loss due to lag time.
  • Whole-house heaters – larger and more expensive water heaters that can operate more than one outlet at a time.
  • Hybrid heaters – combines the functions of a tank and tankless water heater. This can be installed using your existing water heater setup. It has a heat pump that pulls and heats surrounding air and expels cooler air back to the location it is installed.

Advantages and Disadvantages of a Tankless Water Heater

Having a tankless water heater has a lot of benefits, but it also has its drawbacks.

Advantages:

  • It can give instant hot water on demand. You’re not limited to how much your tank can hold; you can enjoy an endless supply of hot water in your home.
  • It’s more energy efficient as it produces no standby heat loss.
  • It lowers energy bills up to 20% as compared with using a standard tank water heater.
  • It lasts up to 20 years, which is twice as long as a tank-style unit.
  • It takes up less space and can be installed on virtually any wall in your home. Traditional water heaters need around 16 square feet of floor space.
  • It poses no possibility of flooding because of a ruptured tank.
  • Electric models don’t produce greenhouse gases.
  • It is usually operated by remote control for your convenience.

Disadvantages:

  • It costs twice to thrice the price of a tank water heater.
  • If you’re using a gas-fired heater, you may need a larger natural gas line to bring enough fuel to the unit.
  • Gas models need annual servicing, which gives you additional annual expenses.
  • Gas-fired heaters produce greenhouse gases.
  • Venting gas and propane units require stainless steel tubing, which is expensive.
  • Electric models need additional circuit and require a lot of energy.
  • Lag time may cause you to let cold water run while waiting for the hot water.

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