We have all heard the term “sick building” referring to an improperly ventilated office building or hotel. But this term applies to industrial facilities as well. Winter conditions can make the situation worse when doors and windows are closed to keep heat in. In this article we will cover some of the things that you need to know about industrial heating applications to keep from causing sick building syndrome in your facility.
PROBLEMS CAUSED BY IMPROPER VENTILATION AND HEATING
Heating an industrial plant in the winter is more than merely blowing some hot air into your workspace. There are a number of questions to take into consideration:
- What is the inside temperature you want your plant to be?
- Should it be kept just above freezing to keep machinery working properly and water pipes from freezing up or does it need to be warm enough for workers to do their jobs in shirtsleeves for maximum mobility?
- Does the space need to be heated differently at different times of the year?
Cold winter temperatures create challenging problems for industrial plant ventilation that can be solved with the proper application of heated air makeup units. Heated makeup air is replacement air. If you have exhaust fans and/or process exhaust systems in your plant, the resulting negative pressure inside a closed building in the winter will cause cold drafts and an uncomfortably cold working environment.
In the past, in order to keep some areas inside a plant from being cold, building owners installed space heaters or infrared heaters that are hung off the ceiling or columns. This created areas of heat where workers could gather to get warm, but once they went back to their workstations, they were cold again. With total heated air makeup, the entire building volume under one roof maintains itself at a comfortable working temperature that’s conducive to higher personnel and process productivity.
DETERMINING THE SIZE/TYPE OF HEATER
Before we begin to determine the amount of heat required for industrial heating applications, we need to calculate the total building heat loss:
- How much heat is lost through the exterior walls and roof of the building?
- How much heat is lost through the process air that’s being exhausted from the building?
- How much heat is lost through doors, windows, and loading docks?
Once we have this information, we can determine the amount of heated air makeup (in terms of CFMs and BTU/hr heating capacity) that would be required to increase the incoming air temperature from whatever the outside temperature is to the desired interior air temperature.
Typically, we tend to try and create a slight positive pressure within the building so that the building leaks heat rather than allowing cold drafts to infiltrate around loading dock doors or other building openings. For an enclosed industrial building in Texas, for example, this equates to about one air change every 20 minutes in the wintertime.
Heated air makeup systems can be provided in a number of configurations (hot water or steam coils, indirect gas fired). However, in our experience, the most cost effective way is with direct natural gas-fired heated makeup units. Natural gas is abundant and inexpensive compared to other heating methods. One hundred percent of the heat of combustion goes directly into the incoming fresh air stream. Other methods don’t come close to this level of efficiency.
WHY WE PREFER DIRECT NATURAL GAS-FIRED SYSTEMS
COMBUSTION BY-PRODUCTS
At first, customers may have questions about direct natural gas-fired heated makeup systems for industrial heating applications. They are concerned that the products of combustion are going into the air, but this simply isn’t the case. With natural gas, the combustion is so thorough that only small amounts of water vapor and C02 are released back into the air, comparable to the breath we exhale on a regular basis.
Even in underground situations, we have used this method to prevent mine freeze-ups. In these applications, the safety of these systems has been overwhelmingly approved by the Bureau of Land Management in many US states. If this technology is safe enough for use in underground mines, you can rest assured it is also safe for your plant.
PRECISE INDOOR TEMPERATURE CONTROL AND RESULTING FUEL SAVINGS
Because we use natural gas, we can modulate the gas flow and control the temperature output so that you’re only using just the amount that’s required to bring your building temperature up to the desired level. There is no concern for steam condensate or water return pipe freeze-ups with a direct natural gas fired unit. With a direct natural gas fired air makeup unit, 100% of the heat of combustion goes right into the airstream for maximum heating efficiency and fuel savings.
SMOG/FOG REDUCTION
From a total personnel health and factory environmental point of view, because fresh outside heated air is being supplied continuously, the resulting air change rate eliminates the buildup smog within the building. In the wintertime, it’s not unusual to walk into an improperly ventilated manufacturing facility and not be able to see from one end to the other. The air can become filled with process smoke, oil, welding fumes, or in some cases (like in a coating or plating facility, for example), an area might be filled with water or solvent-based fog. Keeping the air free from these unhealthy particulates is an added benefit to a winter ventilation system using heated air makeup units.
YEAR-ROUND BENEFITS
Another benefit to using a heated air makeup unit is that the natural gas heating feature can be turned off so that your plant can benefit by running the unit as simply a fresh air supply fan. For many factories, just having a constant supply of fresh air coming into the space can do a lot to keep your employees comfortable and productive!
MORE COMFORTABLE WORKING CONDITIONS = HIGHER PRODUCTIVITY
Manufacturing facilities that are ventilated with heated air makeup units in the wintertime not only create an atmosphere for higher productivity throughout the plant, but it also create an environmentally cleaner condition within the building. You can remove cold drafts, maintain a clean environment, and utilize all of the plant’s interior workspace while keeping employees comfortable.
With no obligation, we would be glad to visit your plant and make recommendations to properly apply and install heated air makeup equipment for any industrial heating applications. Contact Eldridge today.