View Full Version : MAKE-UP AIR
I am looking to install 17 stacked speed queen dryers (34 pockets). The factory recommended make up air is 1 sq ft of opening to the outside per pocket. 34 sq ft is approx 6ft x 6ft Square. Does any body have any experience or input on a fan assisted (perhaps variable speed) make- up air system that is activated by an air pressure switch located behind the dryers? Could airflow thru the dryers and hence dryer efficiency be improved by maintaining positive make up air pressure? Also what are the advantages and disadvantages to have more than the recomended make-up air?
Cheers
Stew
Duane
12-12-2003, 07:33 PM
Having more than the recommended for make-up air is good. 25-50% extra is always ideal for make up air.
I don't have any experience with fan assisted, but it would seem the cost of the fan and the cost to run it would be an extra burden on your bottom line when normal make up air vents would do the same thing at no extra cost.
If your fan goes down during a busy Sunday, you could end of damaging some customers clothes or most of the dryers would stop drying all together.
Howard
12-13-2003, 12:59 PM
Extra Make-Up air, if provided by a fan, would be a BAD thing not a good thing. What Duane says about excess openings for make-up air is true - but this would not apply to a fan. If you run a fan and over pressurize the area behind the dryers with excess air you will adversely impact the dryer operation.
kmdigital
12-15-2003, 08:54 AM
Being a licensed HVAC Contractor, I have some knowledged of makeup air requirements.
In general, the area behind a dryer isn't sealed tightly enough to be able to pressurize it without also pressurizing the entire building. This is detrimental to space heating and cooling costs because all that air has to be heated or cooled, (assuming you are in an area of the country where this is required). For the best HVAC efficiency, ideally, the pressure inside a space should be equal to the the outside to reduce excessive infiltration or exfiltration.
If heating costs aren't a concern, a standard outside air intake will work just fine, and it will self regulate as required (and is the cheapest and most troublefree). If you live in an area where it gets pretty cold then you may want to use a larger damper divided into sections with motorized actuators. These can be controlled by pressure transducers, air temperature or number of dryers running. If you don't put in a damper, and it gets down below freezing, a large air intake (like 6x6) can let a great deal of heat excape outside.