Properly Sizing An Exhaust Fan And Evaporative Cooler In Dry Cleaning Plants
Almost every Dry Cleaner uses Evaporative Coolers, or Swamp Coolers as they are often called, in the plant or clothes cleaning area. Using refrigerated air conditioning would be very 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 by 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 in figuring 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 will give 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 will have to measure from the floor to the roof deck. I say roof deck because I never recommend installing a ceiling in the work area. This will keep 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 will 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 that are used in Dry Cleaners are Grainger fans. There are Grainger stores in most of the major cities in the United States, which makes it very convenient for purchasing fans and parts. I have bought exhaust fans from Grainger for years. I have also 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 you can receive this discount at any Grainger store throughout the country.
Next, you will have to make up the exhausted air with an Evaporative Cooler. These really work great in dry climate areas. But also in more humid areas they give some cooling. You may only get a 10 degree temperature drop in a more humid area, but on a 95 degree day, a light breeze of 85 degree air can feel good while you are working over a hot press. On a Dry Cleaner plant you will usually find them using large commercial or industrial Evaporative Coolers. For the work area that I sized above you would need to install a 15, 000 CFM Cooler. Keep in mind that when you are looking at Coolers, they usually give the CFM ratings in free air. Since you will probably have a duct system cooling the work area, there will be 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 generally drops the CFM rating by a couple thousand CFM. The reason this match is good is because you will 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 Coolers used in Dry Cleaning work areas is the Champion 14/21 SD or the Essick 14/21 SD. These are very common probably because they are the most inexpensive models sold. If you are willing to spend a little more money, I would recommend using 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 superior Coolers, you can type these Cooler model numbers into a search engine and find articles written about them.
I know that in this article there is a lot of technical information that could be boring to some people, but if you are wanting to cool a Dry Cleaning plant I would 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 that I have given will help others in the future.
