How Do Tankless Water Heaters Work?

How Do Tankless Water Heaters Work? - The tankless water heater is also familiar as on-demand, instantaneous, continuous flow, inline, instant-on, the point of use or geyser water heater. The staple working principle of a tankless water heater is to deliver hot water flow within few seconds after open the faucet without retaining any water in the tank except the stream is in the heat exchanger coil.

The tankless water heaters are broad categories in two flavors: electric and fuel-fired. The fuel-fired water heaters commonly used natural gas or propane heat exchanger to boil the water flows through it. Fuel-fired type water heaters required enough free space for ventilation purpose or some models equipped with vent pipe at the top to pass away exhaust gases. With that said, electrical water heaters only have a power cable connecting the thermostat of the heating device with home electric service panel. Usually, fuel-fired water heater gives more flows than the electric one.

Electric Tankless Water Heaters – are compact consume less space and easy to install. As like fuel-fired heater, electric type does not require any venting pipe or free air ventilation space for emitting any harmful gasses. So, they are flexible enough to install right before the point of use like the bathroom, dishwasher or under the sink as you want. The more close you set it to the fixtures, more rapidly you get the hot water.  

Electric tankless heater use electricity powered heating elements instead of the gas burner to heat up the water flows through it. It converts the electrical energy into the heat energy. Heat loss is minimal as the water directly contacted with the heating element.

Working Procedures of the Electric Tankless Water Heater:

The working procedure of both gas and electric water heater almost same except in electric it heats up by heating elements instead of a heat exchanger. The steps of the working of an electric tankless water heater are as follows-

Step 1:  Turn on the fixtures to get the hot water flow

Step 2: Cold water flows enter into the process, and a sensor sends a signal to the internal computer control unit which called electric control unit (ECU)

Step 3: The electronic control unit (ECU) activate the heating element and heating element transfer heat into the water which comes into contact with it.

Step 4: Enjoy the endless stream of hot water.

To operate it required minimum water flow, otherwise, it will not start working. When you puss the off button of hot water it instantly stop heating. So, there is no chance of misuse excess energy.

Fuel-fired Tankless Water Heaters – run by natural gas or propane or kerosene. The pre-requisite to install this type of water heater having enough ventilation to give out harmful gasses emitted from the combustion chamber. As a substitute some model equipped with vent pipes on top of the device. This types of tankless water heater are the excellent option for big houses where there is high demand for hot water. Also, it is low cost than electric type.

The Working Procedures of Fuel-fired Tankless Water Heater:

The working procedures of the gas tankless water heater and traditional water heater are almost same. The only difference is one has a storage tank and other not. The step by step working procedure of fuel-fired tankless water heater are as follows-

Step 1:  Turn on the fixtures to get the hot water flow

Step 2: Cold water flows enter into the process, and a sensor sends a signal to the internal computer control unit which called electric control unit (ECU)

Step 3: The electronic control unit (ECU) activate the heating element and heating element transfer heat into the water which comes into contact with it.

Step 4: Enjoy the endless stream of hot water.

To operate it required minimum water flow, otherwise, it will not start working. When you puss the off button of hot water it instantly stop heating. So, there is no chance of misuse excess energy.

Fuel-fired Tankless Water Heaters – run by natural gas or propane or kerosene. The pre-requisite to install this type of water heater having enough ventilation to give out harmful gasses emitted from the combustion chamber. As a substitute some model equipped with vent pipes on top of the device. This types of tankless water heater are the excellent option for big houses where there is high demand for hot water. Also, it is low cost than electric type.

The Working Procedures of Fuel-fired Tankless Water Heater:

The working procedures of the gas tankless water heater and traditional water heater are almost same. The only difference is one has a storage tank and other not. The step by step working procedure of fuel-fired tankless water heater are as follows-

Step 1:   To get the hot water flow first turn on the hot water tap anywhere in your house.

Step 2:  A flow sensor detects the flow of cold water and sends a signal to the connected Electric Control Unit (ECU),  

Step 3:  At the same instant, the ECU sends a message to a sensor connected with it, activated the gas flow and triggered the igniter.  

Step 4: The igniter sparks and the gas burner heats the heat exchanger until the flame sensor detects a flame. The course of water flow serpentine pattern, it absorbs as much as heat from the body of the heat exchanger.  

Step 5: When the water reached its pre-set temperature, water gets out and flowing through the faucets. Turn it off once fulfill your hot water requirement.

Some gas heater has a combustion fan which draws air to accelerate the combustion process. The second generation tankless water heaters are mostly condensing type which produce heat by using exhaust gases for further combustion. The condensation type water heater reduces energy use tremendously thus helps to save your water bills.

Regardless of the type, the Electronic Control Unit (ECU) is the heart of all modern tankless water heater. It controls all functions like temperature, ignition, gas flow, and modulations. It is also responsible for safety issues. Flame sensors or automatic gas cut off are activated within a second in case of any unexpected failure detected.  

Most of the modern tankless water heater comes with a Temperature Control Unit either wired or wireless. Usually, the temperature pre-set by the manufacturer at 140°F. To avoid scalding and save energy it is recommended to set not more than 120°F. However, you can configure your desired temperature by modulating through ECU.

The ECU can modulate the amount of gas flow entering into the burner based on the water stream, to deliver a constant temperature hot water as per your desire. To do this ECU use the signals from an inflow water temperature sensor and the outflows from the heat exchanger.

In case of instantaneous water heater controlling temperature is as simple as pressing a button. The ECU modulates the thermostat after getting signal from the user. These modern thermostat equipped with LED readouts for control temperature precisely. The help of this, a user can change temperature one degree at a time, which is not possible in traditional dial-up water heaters.  

Either gas or electric, ignite the burner or power the heating element you required a trusted Power Supply system. Most of the water heater using the home power supply to run the device. Some differences seem that using small water turbine, which produce energy created by the water flowing through it. Some portable tankless water heaters are using only battery power. Though the cost of ignition for a turbine system is zero, it is expensive and extensive in size compared to other models.

In spite of the differentiation of the tankless water heaters, the working principle is more or less same to all.

  • The entrance of cold water into the water heater device immediate after open the fixtures of hot water.
  • The water flows detected by a sensor which triggered the igniter to spark the gas burner or start the heating element to heat the water in the heat exchanger.
  • Cold water absorbs heat from the heat exchanger and delivers hot water at your faucet
  • The ECU modulate the gas burner to maintain constant water temperature and take care safety aspects.

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