Exhaust fans

[daniabeach]

I'm in real need of help and quick. I have a 1500sqf facility about a mile and a half from the beach in south florida. I also have 2 huge central A.C. units, which I have only turned on twice since I purchased this location. My question is about how good it would be for me to install a few exhaust fans, would it really save me any money, is it worth it. I really need help, if their is anyone who has had experience with these type of fans, your info would be highly apreciated.

[kern]

Hi Dan... I have a 1400 sq. ft. mat with two A/C units. One is 5 ton and the other is 3.5 ton. They are located at opposite ends of the mat and are roof units with the heat exchanger inside the ceiling and duct work to feed cool air to the length of the mat. We are in upper New York State and it gets into the high 90s with high humidity during the dead of summer. We've found that opening doors and fans and such only work to cool off the mat if the outside temperatures are at least 10 degrees cooler than inside the store. The bigger the difference the better. But even then, only the areas immediately next to the fan or door get cool. There are several hot spots when trying to cool this way. Also, fans and open doors won't work if the outside air is very humid. And cooling with fans and doors may only work in the early AM or late PM if it gets hot outside during the day.

The net is, based on our experience, is to use the A/C units. Turning the units off when no one is in the store will save $$$. But you should install a timer so that they come on about an hour before opening time. A timer connected to a rely that opens the thermostat circuit can be used to control the on and off times.

We've found the extra cost of running the A/C units is very much offset by customer reactions. Very often we hear our customers exclaiming "I knew I wanted to do my laundry today" when they first enter the cool store. BTW, in our area most mats don't have A/C so we see it as a draw. We advertise this feature with our lighted window sign "WE'RE COOL INSIDE" or "AIR CONDITIONING IS ON IN HERE" and things like that.

Also, fans will serve to bring in dust (and pollens up here) to the inside of the mat, creating a real mess very quickly. This is especially true if you're located near a highway with truck traffic.

Hope this helps. Bill

[LEEHUSTON]

I love when the other mats in my area don't run the A/C, gives me a competitive advantage. Has anyone ever heard of another retail business that does not use air conditioning even when it is installed and working perfectly?

[TKLaundry]

How do you combat the loss of AC treated air from the building vents behind the dryers? In my next mat I will definately consider putting in AC but that is something that I figure would be akin to running the AC at home with a window open?
Dave

[kern]

Here's how we keep the cooled A/C air inside the mat. The most important first step is to make sure you have more than enough make up air coming into the back of the dryers from outside the building, NOT from inside the mat. In fact, we designed 30% extra capacity than we really needed.

Next, the facade over the top of the dryers should be as tight around the dryers as possible. It should extend to the ceiling. By having more than enough make up air and by having a wall that separates the rear of the dryers from the front (and hence from the cool A/C air) there should be minimal cool air pulled into the rear of the dryers.

Also, all ceiling tiles in the mat must be kept in place and be in good repair. If not, the hot air above the ceiling will be pulled down into the mat.

If you want to test for air flow, you can use a punk stick or, dare I say it, a cigarette. Just place the stick near where you want to check and you will see which way the wind blows or is being sucked. BTW, if you find it difficult to open the front door when all the dryers going, you don't have enough make up air. This assumes your door opens out. If it opens in, then the door will want to stay open if you don't have enough make up air. Hope this helps.

[LEEHUSTON]

I think it is nearly impossible not to to pull some of the condtioined air into the dryers. I have put insulation under the dryers, allowed for extra make up air and installed ceiling fans to keep air moving in the store. There is still going to be some wasted a/c, but that is a cost of having a comfortable place. I am sure that restaurants and many other retail establishements waste some ac too, but they don't cut it off and let their customers suffocate, if they did they would be out of business.

[LEEHUSTON]

We also have progamable thermostats that turn the air off at closing and back on in the morning.

[daniabeach]

THANKS EVERYONE FOR THE GRAT RESPONSES