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A boiler economizer is a device that is designed to increase the operating efficiency of a boiler, cutting down on its operational costs over the lifetime of the boiler. Although the savings on any given day may be relatively small, the impact over time can be significant, especially with a large boiler system, such as the type used to heat large buildings like office buildings and institutions. Some boilers are designed with economizers built in, while in other cases, an economizer can be fitted on after the fact.
Boilers operate by heating water to make steam, and using that steam for heat or energy generation. For the most part, a boiler is fairly efficient, but there is some heat loss when the byproducts of combustion are vented. The byproducts of combustion are still hot, often quite hot, and when they are simply vented, this represents lost heat for the boiler.
A boiler economizer acts as a waste heat recovery device, ensuring that this heat does not go unused. Instead, the heat is used to essentially preheat the water, so that less heat is required to bring the water to a temperature high enough to make steam. One could think of this device as a feedwater heater; it ensures that the water used to feed the boiler to make more steam is hot so that the boiler does not have to expend as much energy heating it.
Using an economizer does not just prevent heat loss — it can also extend the life of the boiler. Temperature changes caused by using cooler feedwater can create wear and tear on the boiler over time as the fittings heat and cool down cyclically. When the feedwater is heated, the temperature differential is less extreme, putting less strain on the boiler and giving it a longer operating life. Since a large boiler system can be expensive to repair or replace, this adds to the overall savings on the heating system.
When someone installs a boiler economizer, it is important for him or her to use a product that is suitable for the boiler. Some manufacturers offer economizers for their boilers, while companies that make standalone devices can come to inspect the boiler to determine which product would be most suitable. A heating and cooling specialist can provide additional advice about installation, including a breakdown of how much an economizer can save. There may be cases in which it is not fiscally responsible to install this device because the costs of installation may outweigh the savings.