Varmereservoir

Varmereservoir, or hot water reservoir, is a storage tank used in heating and domestic hot water systems to hold heated water for later use. It functions as thermal energy storage, decoupling heat generation from consumption and allowing intermittent heat sources such as solar collectors or heat pumps to supply demand on a flexible schedule.

In contemporary installations, reservoirs are typically closed and pressurized, though open-vented configurations exist in older or certain regional systems. Domestic-scale tanks usually range from about 100 to 300 liters, while larger capacities serve commercial or district applications. Many reservoirs include a heat exchanger coil or internal baffles to transfer heat from a primary circuit to the stored water.

Key components commonly found in varmereservoirs include insulation, an inner tank (often enamel-lined steel or stainless steel), a sacrificial anode for corrosion protection, a heating element or a connected heat exchanger coil, an expansion vessel, and a temperature/pressure relief valve. Heating sources may include a boiler, solar thermal system, or heat pump. Temperature control and, in some systems, stratification features help maintain a usable hot-water layer at the top.

Operation involves receiving heated water and storing it at a target temperature for later withdrawal. To limit bacterial growth such as Legionella, storage temperatures are typically maintained around 60°C or higher, with mixing valves used to deliver lower temperatures for tap water when needed.

Advantages of a varmereservoir include reduced boiler cycling, better utilization of intermittent heat sources, and improved supply reliability. Drawbacks can include standby heat losses, potential for mineral buildup or corrosion without proper maintenance, and higher initial costs. Design considerations cover capacity, insulation, system pressure compatibility, and integration with the chosen heat sources.