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Water heating

technology Maturity 11-13 Next article →

Water heating is a heat transfer process. It uses an energy source to raise water above its initial temperature.

Water Heater White
Water Heater White

This process is vital for many daily tasks. We use hot water for cooking, cleaning, and bathing. In many homes, it is also used for space heating. In industrial settings, water is often heated until it becomes steam.

Ancient Water Heater
Ancient Water Heater

This steam and hot water serve many different mechanical purposes.

Traditional methods of heating water involved using metal vessels. People used tools like kettles, cauldrons, pots, or coppers. These vessels heat a specific batch of water at one time. However, they cannot provide a continuous supply of hot water at a set temperature.

Kerosene water heater, 1917
Kerosene water heater, 1917

In rare cases, hot water occurs naturally through natural hot springs. Modern technology has moved toward appliances that provide a steady flow of heat. These appliances have many names depending on the region and use. They might be called boilers, geysers, or calorifiers.

Storage water heaters are a common type of appliance.

FEMA - 63 - Photograph by Dave Saville taken on 10-04-1999 in North Carolina
FEMA - 63 - Photograph by Dave Saville taken on 10-04-1999 in North Carolina

These consist of a cylindrical vessel that keeps water continuously hot. In North America and Southern Asia, these tank-type heaters are very popular. Typical household sizes range from 75 to 400 liters. They can run on electricity, natural gas, propane, or heating oil. In the United States, natural gas is often the most popular choice. This is because gas is frequently piped through cities and is cheap to use.

These storage tanks work by holding heat for later use. This allows the system to use energy at a relatively slow rate. However, there is a downside to this design. Over time, heat escapes through the tank walls. This causes the water to cool down. When this happens, the heating system must turn on to heat the water again. To improve efficiency, manufacturers invest in better insulation for the tank.

WH safety valve
WH safety valve

Large tanks also help prevent temperature changes during moderate water use.

Another major type is the instantaneous water heater.

Water heater bathroom
Water heater bathroom

These are also called tankless or on-demand water heaters. They do not store water internally, except for what is in a heat exchanger coil. Instead, they heat water instantly as it flows through the device. Many of these units use copper heat exchangers. Copper is preferred because it has high thermal conductivity. This means it moves heat very easily. These heaters provide a plentiful, continuous flow of hot water. However, they have a much higher initial purchase cost than tanks.

Solar energy provides another way to heat water.

solar heater dsc00632
solar heater dsc00632

Solar collectors are installed on roofs or walls to capture sunlight. There are two main types of solar thermal models. The first is the direct-gain type. In this system, potable water is sent directly into the collector. The second is the indirect or closed-loop system. In a closed-loop system, a heat transfer fluid moves through the panels. This fluid might be a mix of water and antifreeze. The fluid then passes through a heat exchanger to heat the potable water.

Solar heating is extremely successful in certain parts of the world. In Cyprus and Israel, 90 percent of homes use solar water heating.

Flat-plate solar thermal collector, viewed from roof-level
Flat-plate solar thermal collector, viewed from roof-level

In other regions, such as Scandinavia, Finland, and Poland, people use district heating. This is a large-scale system for densely populated urban areas. It provides energy for both water heating and space heating. These systems use combined heat and power (CHP) plants. These plants might use incinerators, central heat pumps, or waste heat from industries. This connects individual home heating to much larger industrial and energy systems.

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🖼️ Images & Media (13)
File:Active Indirect Water Heater Diagram.svg
Active Indirect Water Heater Diagram.svg
File:Water Heater White.jpg
Water Heater White.jpg
File:FEMA - 63 - Photograph by Dave Saville taken on 10-04-1999 in North Carolina.jpg
FEMA - 63 - Photograph by Dave Saville...
File:Boiler and Cylinder.jpg
Boiler and Cylinder.jpg
File:Water heater bathroom.JPG
Water heater bathroom.JPG
File:solar heater dsc00632.jpg
solar heater dsc00632.jpg
File:Flat-plate solar thermal collector, viewed from roof-level.png
Flat-plate solar thermal collector,...
File:Ancient Water Heater.jpg
Ancient Water Heater.jpg
File:Kerosene water heater, 1917.jpg
Kerosene water heater, 1917.jpg
File:ModCon boiler system.jpg
ModCon boiler system.jpg
File:WH safety valve.JPG
WH safety valve.JPG
File:Scaldburn.jpg
Scaldburn.jpg

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