Indirect And Direct Fired Make Up Heaters: Pros And Cons


Industrial projects and construction sites often need to rent or buy heaters in order to make sure they can continue the job in adverse conditions. In such situations, the company has a choice to make. Should the employ indirect or direct fired make up heaters. Each type has its pros and cons. Companies and managers need to understand the specifics of their site and/or project in order to ensure the type they choose is compatible with its intended environment.

Direct-Fired Heaters

Direct-fired heaters come in two major types:

  1. Open flame or torpedo style
  2. Make-up air unit: This unit does not remove any air from the interior but uses exterior air to provide heat for places where air is limited, unavailable or unable to be reused

They produce a visible flame. You can see it ignite and grow as the energy source acts as a fuel. A direct-fired heater may burn natural gas, propane or fuel oil. The result is a fuel-efficient flame that increases the temperature in the area. In fact, this type of heater is almost 100% energy efficient. This also makes it a cost-effective solution for heating a room or large area.

Another advantage of such heaters is the ability by a manufacturer to customize the heat transfer sections of the heater to meet the specifications of the customer. This provides for a flexibility lacking in other types of heating units and systems. However, with direct fired make up heaters, it is also essential to have in place some form of ventilation system. The heater does release toxic fumes requiring dispersal. On open-air construction sites, this does not present a problem.

Indirect Fired Heaters

Indirect heaters have a separate heat exchanger. This means the air you breathe in on a site differs from the sir the heater uses for combustion. The energy source is the same as for a direct heater: natural gas, propane and fuel oil. However, while there is less to worry about ventilation and moisture than with other heaters, other concerns exist, including positioning. An indirect fired heater needs to be positioned out of the room or space requiring heating. Ductwork will conduct the hot air to its location.

Indirect and Direct Fired Make Up Air Heaters

Heaters are essential to ensure employees can continue their work on a job site with minimal discomfort. These devices also allow a company to extend its capabilities to extend the date of a site well into the colder months of the year. Depending upon the characteristics of the site, the legislation of the region and the needs of the workers, you will usually make a decision to employ one of two types of heaters: indirect or direct fired make up air heaters.

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