- General

Sizing the Exhaust Fan and Evaporative Cooler in Dry Cleaning Plants

Almost every Dry Cleaner uses Evaporative Coolers, or Swamp Coolers as some call them, in their plant or clothes cleaning area. Using refrigerated air conditioning would be too expensive for them. Their steam boilers are putting out hundreds of thousands of BTU’s of heat into the work area. To remove this much heat using air conditioning would cost thousands of dollar per month. Because of this, the work area of the Dry Cleaner should have an Exhaust Fan that is capable of making a complete air exchange about every 1 1/2 minutes. Let me give you an example to help you figure the correct size exhaust fan for your Cleaner.

Let’s say you lease a space in a shopping center that is 25 feet wide by 80 feet deep. The total square feet of this lease space is 2,000 sq. ft. Usually the front sales area is heated and air conditioned. Next, remove from the 2,000 sq. ft. your sales area of 25 feet wide by 15 feet deep which totals 375 sq. ft. This leaves you with 1,625sq. ft. The boiler room is 10 feet by 10 feet (100 sq. ft.) and the restroom is 6 feet by 6 feet ( 36 sq. ft.) which total another 136 sq. ft. usually not figured in to the cooled area.. This gives you a final total of 1,489 sq. ft. of floor space in the work area to exhaust and cool. To get the cubic feet of the work area you should measure from the floor to the roof deck. I say roof deck because I never recommend installing a ceiling in the work area. This only keeps the heat lower in the room and makes the work area much hotter. Multiply the 1,489 sq. ft. by the 15 ft from the floor to the roof deck and you get a total of 22,335 cubic feet of area to exhaust. Divide 22,335 by 1 ½ (the amount of minutes per air change) and get the total number of cubic feet of air to remove every minute, or the CFM. Under these conditions, I would install an exhaust fan that is rated at about 15,000 CFM. The most common exhaust fans used in Dry Cleaners are Grainger fans. There are Grainger stores in most of the major cities in the United States, which makes it convenient for purchasing fans and parts. I have bought exhaust fans from Grainger for years. I have learned of a way that any customer of Grainger, even if you have never bought from them before, can get a 10% discount on their fans. If you e-mail me I will let you know how that you can get the discount at any Grainger store in the country.

Next, you have to make up the exhausted air with an Evaporative Cooler. These work great in dry climate areas. But even in more humid areas they give some cooling. You may only get a 10 degree temperature drop in a humid area, but on a 95 degree day, a light breeze of 85 degree air can feel good while working over a hot press. On a Dry Cleaner plant you will usually find them using a large commercial Evaporative Cooler. For the work area that I sized above you would need to install a 15,000 CFM Cooler. Keep in mind when you look at Coolers, they usually give the CFM ratings in free air. Since you will probably have a duct system cooling the work area, there is static pressure or restriction on the air flow from the Cooler. If you use a 15,000 to 16,000 CFM Evaporative Cooler, you will probably have a good match with the 15,000 CFM exhaust fan. The static pressure of the ductwork will generally drop the CFM rating by a couple thousand CFM. The reason this match is good is because you want a slight amount of negative pressure in the work area, in other words a little more air exhausting from the room than is being supplied into the room. The most common Evaporative Cooler used in Dry Cleaning work areas is the Champion 14/21 SD or the Essick 14/21 SD. These are the most common because they are the most inexpensive models sold. If you are willing to spend a little more money, I recommend going to a Cooler that will last far longer. The Champion AS150 or the Champion AS15012 are better built and longer lasting Coolers. If you want a better explanation of the reasons why they are better Coolers, you can type these Coolers into a search engine and find articles written about them.

I know there is a lot of technical information that would be boring to many people, but if you are wanting to cool a Dry Cleaning plant I recommend using this information. I have installed exhaust and cooling systems in Cleaners for decades in the Dallas/Fort Worth, Texas area. These formulas and equipment have worked great. I hope these tips I have learned will help others in the future.