Construction of a water heater tank

The Design of a Hot Water Heater Tank can facilitate direct or indirect water heating.

Indirect heating involves heating tap water by cooling the technical water used as an intermediate heat carrier between the heat source and the water being heated, through an embedded or external heat exchanger.

Direct heating involves heating tap water with an embedded electric heating element in the tank. Water heaters with direct heating are not represented in our catalog.

The Operating Principle of an Indirect Water Heater Tank is a steel tank covered with thermal insulation on the outside and enamel on the inside, suitable for contact with drinking water. Depending on the application scheme, water heaters can be equipped with:

• One built-in tubular heat exchanger
• Two built-in tubular heat exchangers
• External plate heat exchanger
• Magnesium anode
• Electric heating element

Water heaters with one built-in heat exchanger are widely used in hot water supply systems with one heat source, if the surface area of the built-in heat exchanger ensures the heating of water in a specified time.

Water heaters with one heat exchanger are installed in HWS systems:

• Private houses with any types of heat sources.
• Apartment buildings and administrative buildings with a gas boiler room as a heat source.

The built-in spiral heat exchanger is made of copper or stainless steel and is located in the lower part of the tank.

A water heater with two built-in heat exchangers is used in systems with combined heat generation from two or more sources. They are widely used in hot water supply systems for private houses, where the main heat source is a solar collector and the water is heated to the required temperature by a gas or electric boiler.

The main low-temperature heat source, such as a solar collector or a heat pump, is connected to the lower heat exchanger of the water heater, while the secondary high-temperature heat source, such as a gas, solid-fuel, or electric boiler, is connected to the upper heat exchanger.

A water heater with an external heat exchanger is used when serially installed heat exchangers do not provide enough time for water heating. Advantages of tanks with an external heat exchanger and loading system:

• Easy cleaning
• Fast heating of the entire volume of water
• Low temperature of the heating medium
• Layer-by-layer water heating (see Working principle for details)
• All water supply is heated to the same temperature
• The heat exchanger is selected to match the working conditions
• Several storage tanks can be connected to one loading system
• Heating time depends on the heat exchanger's power and can be set during calculation
• More cooling of the heating medium increases the efficiency of the condensing boiler and reduces the necessary costs for centralized heating
• The operating mode of the storage water heaters should exclude the entry of cold water from the bottom to the top of the tank, as a high temperature difference can damage the internal anti-corrosion coating

The internal surface of the storage water heaters is protected from corrosion by enamel coatings suitable for use with drinking water and is sometimes complemented by cathodic protection devices. The presence of a magnesium anode significantly extends the life of the tank's body, protecting it from corrosion, but the deteriorating anode will periodically need to be replaced.

The thickness of the thermal insulation of the water heater determines the amount of heat loss and the speed of its cooling, so in systems that require prolonged storage of hot water, it is recommended to choose a thicker thermal insulation structure. Thermal insulation is usually made of mineral wool or rigid polyurethane foam.

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