A relatively new concept to the greenhouse industry is to use hot water storage with alternate fuel (biomass) heating systems to limited cycling. Systems, such as wood, burn most efficiently if operated at a constant fire rate. Adding a large, insulated hot water buffer tank can store excess heat during the daytime operation to be used at night when the heat demand is the greatest.
Heat storage tanks are also fairly common in operations that use their boiler system to generate CO2 during the day. Like the biomass system this hot water is stored for use when CO2 production isn’t required.
Tanks with capacities of up to 1,000,000 litres are available. They are usually steel with an interior liner or anti-rust coating and heavy insulation on the outside. An exterior aluminum jacket protects the insulation. Most tanks are assembled on site.
Design of these systems allows for a smaller boiler as the water storage carries part of the nighttime load. Typical design looks at the maximum heat needs for the coldest day. It also considers the maximum tank water temperature that can be achieved, the lowest water temperature that can be used and the storage period.
Having a heat storage tank can also add piece of mind. In the case of a boiler failure a heat storage tank can supply 12-24 hours of hot water to sustain operation until repairs can be made.