When you need temporary or supplemental heating for your construction site, industrial site, office building, retail store or restaurant, a portable industrial heater, construction heater or commercial heater is the answer. Portable heaters can improve the comfort, productivity and safety of workers and maintain the required ambient temperature for various construction activities and manufacturing processes. 

Choosing the best portable industrial heater for the application comes down to understanding the amount of heat you need to generate and which heater types are appropriate for use in which environments. This guide helps you identify the safest, most convenient and most economical choice for your application.

Direct fired heaters: Ideal for large, well-ventilated spaces

Direct fired heaters have an open flame and are typically fueled by propane or natural gas. They are ideal for heating large, open spaces such as outdoor construction sites, buildings that aren’t yet fully enclosed and large industrial or commercial spaces, including warehouses.

Because they generate combustion byproducts such as carbon dioxide and carbon monoxide, they are safe to operate only in spaces with plenty of ventilation or air circulation. Some localities ban their use in certain cases.

Direct fired heaters are by far the most efficient choice; they convert about 95% of the fuel used into heat. As a result, they are the cheapest heaters to operate. They are also less expensive to rent than indirect fired heaters.

The burner never shuts off, so they provide constant heat, which makes them ideal for concrete and masonry pours. A modulating valve can keep the temperature of the space within a narrow target range.

Direct fired heaters heat outside air rather than recirculated indoor air.  As a result, they bring in moisture. That makes them a poor choice when a dry environment is required, such as when drywall or finishings are being installed or are in place.

There are two main types of direct fired heaters: open flame and enclosed flame.

Open flame direct fired heater

Open flame direct fired heaters have an exposed flame—look closely and you can see it. They produce the most heat in a short period. A torpedo heater, aka salamander heater, is the classic example. Open flame heaters may be undesirable in certain industrial settings.

Enclosed flame direct fire heater

These heaters, sometimes referred to as tent heaters because they are suitable for tent parties, contain the flame within a box. They are a safer option compared with open flame heaters because there’s no danger of stray papers, debris, explosive dust or vapors coming into contact with the flame and causing a fire or explosion.

A make-up air heater is one type of enclosed flame direct fired heater. It forces the heated outside air into the space while pushing out the ambient air through a door, window or other opening. Positive air pressure ensures that cold outside air can’t enter the space. The heater provides air that is constantly fresh, but like other types of direct heaters, it generates emissions that must be vented and can’t be used once a space is closed in.

Indirect fired heaters: Clean, dry heat for indoor spaces

Indirect fired heaters use a heat exchanger to produce clean, dry air. Combustion takes place inside the heat exchanger. The combustion byproducts never touch the air being warmed; they are contained in the heat exchanger and released through a flue and chimney.

This type of heater typically sits outside. The warm air is ducted in. The heater can be placed indoors if the exhaust is ducted out.

An indirect fired heater does not heat the air directly, so it is somewhat less energy efficient than a direct fired heater—80% compared to 95%—but still far more efficient than an electric heater.

Because it produces dry air, an indirect fired heater can be used in buildings where finishes are in place or being installed. It’s also a good choice for heating office spaces, commercial spaces, manufacturing facilities, chemical production facilities, hospital buildings and event venues.

These heaters don’t provide the precise temperature control that direct fired heaters provide. The burner shuts off when the thermostat hits or exceeds the target temperature, and the heater blows cold air until the ambient temperature drops and the burner turns on again. The units are larger than direct fired heaters and require more space.

As with direct fired heaters, indirect fired heaters may be prohibited in some locations and circumstances because of the combustion gasses they exhaust. On jobsites where fuel tanks are prohibited, neither indirect fired heaters nor direct fired heaters can be used.

Indirect fired heaters may be fueled by propane, natural gas or diesel.

Propane or natural gas indirect fired heaters

Heaters that run on propane require an external propane tank. Natural gas heaters require a natural gas hookup. Dual-fuel heaters can run on either propane or natural gas.

Both propane and natural gas heaters are well suited to longer-term applications. Large propane tanks eliminate the need for frequent refueling, as do natural gas lines.

Diesel indirect fired heaters

Diesel powered indirect fired heaters are convenient and cost-efficient for short-term applications. They are quick to set up because they have their own tanks. The downside: The tanks require frequent refilling. Diesel fuel is also more expensive than propane or natural gas.

Industrial electric heaters: Inefficient but clean and convenient

 Electric heaters are by far the least energy efficient portable heater option. They convert only 30% of the electricity consumed into heat, which makes them the most expensive type of heater to operate. However, they are relatively compact, operate silently, produce clean air and are simple to install. For heating relatively small spaces, they are a convenient option. In places where fuel-powered heaters are prohibited, or in locations where hooking up to a fuel tank or gas line isn’t feasible, they may be the only option.

Electric heaters come in a range of sizes, from highly portable 15kW space heaters to high-temperature 150kW ductable commercial heaters. They are often used in retail stores, restaurants, buildings that require emergency heating and heavy industrial facilities where electric power is abundant. Because they are hot to the touch, they may not be the best choice for school settings.

Heat pumps: Clean, efficient comfort heating and cooling

Heat pumps represent a unique option for providing temporary heat inside an occupied space. They produce about twice as many BTUs of heat as an electric heater, and unlike electric heaters, they aren’t hot to touch.

Despite their name, heat pumps produce as much cold air as hot air. They can therefore be used for both heating and cooling. To provide heat, they absorb thermal energy from outside air (or the ground) and warm it further through a process that relies on a compressor, evaporator coils, condenser coils and a refrigerant. When used for heating, the cold air they produce is vented outside or ducted into the space above the ceiling.

Because a heat pump can produce both cold and hot air, it may be a good option when applications span warm and cold seasons and in areas that experience large temperature variations from day to night.  

Heat pump applications include comfort heating and cooling for office buildings, restaurants, retail stores, hospitals, medical facilities and schools. Heat pumps may be less suitable for industrial settings. Because the heat output of a heat pump is limited, it may not be ideal in very cold locations.

Working with a knowledgeable temporary HVAC equipment provider

 The right temporary industrial, construction or commercial heater can provide comfort for workers and building occupants and required air temperatures for construction and industrial processes. Because so many heater types are available, each with its own advantages, choosing the best and most efficient heater for the application can be daunting.

Properly sizing the heater for the space is also challenging given the need to factor in a host of variables, including the square footage to be heated, the amount of ventilation in the space, the ducting possibilities, the ambient air temperature and the target temperature.

A vendor with a large selection of portable industrial heaters and a deeply knowledgeable team can help you determine the heat output you need and guide you to the optimal type of heater to warm your space safely and efficiently.

Visit our online marketplace to browse our complete selection of industrial heaters.