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Water heaters: how single and double coil units work
Heating systems

Water heaters: how single and double coil units work

ISAR GROUP7 November 20264 min read

A water heater, or calorifier, produces and stores hot water. Working with a boiler or solar collectors, it keeps hot water ready in the building at all times.

How it works

Inside the tank sits a coil, a tubular heat exchanger. Hot water from the boiler flows through the coil and heats the clean water in the tank. The two never mix: the heating water stays in a closed loop and the domestic water stays clean.

Single and double coil

A single coil unit connects to one heat source, usually a boiler. A double coil unit has two separate coils: one for the boiler and one for solar collectors. On sunny days the water is heated mostly by the sun, and the boiler only tops up what is missing.

The role of insulation

The hot water is stored in the tank for a while. Polyurethane foam insulation cuts heat loss so the water stays hot for hours. A thermometer lets you watch the temperature, and a heater socket allows an electric element to be fitted when needed.

Where it is used

Water heaters are used in hotels, hospitals, sports centres, restaurants, housing and factories. The volume is chosen for the highest simultaneous demand, for example the morning peak in hotels.

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