Design, Construct, and Operate to Control Indoor Humidity

Transcription

1 EHUMIIFITION: Natatorium pplication & Product Guide esign, onstruct, and Operate to ontrol Indoor Humidity The Humidity Expert

2 Munters is the world leader in dehumidification Munters is the largest manufacturer of dehumidifiers in the world. Since developing the first desiccant dehumidifier in the late 93 s, Munters has continued to innovate in the fields of dehumidification and energy recovery. Our long history and extensive expertise in dehumidification makes us the premier choice for your dehumidification needs. Natatoriums have historically posed a difficult environment for the conventional HV system. The continuous moisture load swimming pools generate challenges the mechanical system and creates multiple opportunities for structural damage. The combination of humidity and chlorine not only attack the building, but also provide a breeding ground for mold and bacteria which can jeopardize occupant health and comfort. Munters offers a variety of systems in several different sizes, configurations, and thermodynamic process options to meet the customer s needs. Munters, The Humidity Expert Our extensive knowledge and experience makes us the premier choice for your dehumidification needs.

3 Protect the building and its occupants n efficient HV system must function properly during all seasons and be capable of handling all possible indoor and outdoor air conditions even those abnormal swings. The system should provide precise humidity control because the evaporating water from the pool is continuously released into the air. and must be constantly removed. Space air condition and water temperature must also be balanced for occupant comfort based on the type of pool. (See chart at right). uilding esign It is important to start with the correct envelope construction to avoid significant problems during the life of the building. proper vapor barrier is needed to keep moisture from being trapped in the buildings walls and roof assembly. dditionally care should be taken with regard to the window quantity, design and installation, as well as the wall construction detail and its insulation. ondensation on building elements during low outdoor air temperatures should be carefully guarded against. Please refer to the SHRE handbooks and The Humidity ontrol esign Guide published by SHRE for more information on this subject. oncrete lock Inside the Natatorium F (28 ) %rh ew Point = 7 F (9.4 ) Vapor Retarder Layer FROM SHRE The recommended conditions for pools as indicated in the SHRE pplications Handbook and Humidity ontrol esign Guide: Type of Pool Recreational Therapeutic ompetition iving Whirlpool/Spa Temp ºF 75 to 85 8 to to 85 8 to 85 8 to 85 RH% 5 to 5 to 5 to 5 to 5 to Water Temp ºF 75 to to 95 7 to 8 to 9 97 to 4 Introduce Outside into the uilding Outside air must be brought into the space to dilute the chlorine that has evaporated from the pool and to provide fresh air for the occupants. FROM SHRE Standard calls for:.48 FM PER SQURE FOOT OF POOL N EK RE & 7.5 FM PER PERSON IN THE SPETTOR RE In order to make room for this outside air, mechanical exhaust is required. This exhaust should exceed the outdoor air quantity to maintain negative air pressure in the pool area. Pay special attention that the airflow moves in the correct direction. This ensures that humidity and odors will not transfer into adjacent spaces, and also keeps high humidity out of the wall cavities to minimize the potential for condensation. Prevent ondensation Outdoors F (-7.8 ) Face rick 4 F (8 ) The surface of the interior insulation becomes cold enough to allow condensation to form. The vapor barrier must be installed on the interior side of the installation to prevent water from reaching the cold insulation, where condensation will form. Rigid Polystyrene Insulation High humidity and condensation on the building structure can cause significant damage. detailed dew point analysis of the building is required to eliminate condensation both during initial design and through the end of construction. Thermal bridges in the walls and windows should be analyzed and reviewed carefully to avoid building damage. 2

4 alculate the Loads TOTL HUMIITY LO = O HUMIITY LO + INTERNL HUMIITY LO + POOL LO Pool Evaporation Rate FROM SHRE PPLITIONS HNOOK Evaporation Rate Equation: POOL LO =. X POOL RE X VPOR PRESSURE X USE FTOR Where: Load = the evaporation rate of the pool (lbs/hr) Pool rea = the surface area of the water (sq. ft.) Vapor Pressure = the difference in vapor pressure of the air and water (in of Hg) Use factor = the occupancy factor from SHRE. Type of Pool Residential Fitness lub / ondo Therapy / Elderly Swim Hotel Institutional / School Public Pools Spas and Whirlpools Use Factor Vapor Pressure (Inches of Mercury) Fluid Type Water Relative Humidity % 5% % Temperature ºF Outside Humidity Load FROM SHRE PPLITIONS HNOOK O Humidity Load Equation: use SHRE design dew point conditions: O HUMIITY LO =.57 X O X HUMIITY RTIO Where: Load = the humidity load of the outside air (lbs/hr) OFM = Ventilation Quantity (cfm) Humidity Ratio = the difference in absolute humidity of the outside air and the space (grains/lb) Internal Humidity Load People are an internal load to the space and their activity should be considered in the calculation. Use the chart below to determine the activity load per hour. ctivity per hour Seated at Rest btu/hr 5 lbs/hr. Seated Very Light Work 58.5 Properly calculating the internal and external loads of the facility is a Seated, Light Work 2.2 critical step in designing a natatorium. The HV equipment is sized Walking, Standing based on load calculations and the type of facility being constructed. Moderate ancing n indoor swimming pool has a remarkable chance of experiencing Walking riskly w/loads 3. moisture problems, but with accurate load calculations of the pool Light Exercise 8.83 evaporation rate, peak outside air loads, and the internal load in the Medium thletic ctivity 9.92 space you can successfully design a healthy and enjoyable natatorium. thletics

5 uct esign The air distribution system should be designed in such a way as to minimize stagnation in the building envelope. While keeping velocity over the pool surface low, air movement is desirable to control chloramines. air should be washed over windows and other surfaces that may experience low temperatures in cold weather that might lead to condensation. Exhaust and return air inlets should be located high to capture hot and humid air. Whirlpools should have an exhaust air connection directly above. Exhaust outside air intake to flush out chlorineladen odors Return air vent mounted as high as possible in room Weather-proof Munters dehumidifier sits outside natatorium ry air keeps glass free of condensation and water damage Temperature & humidity controlled room ryer floors ry ductwork resistant to mold and mildew growth ry pool environment helps preserve pool structure from moisture damage uctwork should be aluminum, painted galvanized, 3 series stainless steel or lightweight corrosion resistant fabric. Munters offers ryflo ucting. ryflo ducting is cylindrical tubes constructed of a durable fabric that uniformly disperses air into the space. (See Munters istribution System illustration above.) hoose pool technology best suited for that region Weather is a critical component of the building load. When climate is hot and dry, it presents different challenges for a HV system than when it is hot and humid. iffering outdoor conditions require specific performances from dehumidification and air conditioning systems. The same type of system throughout the country will not efficiently meet the needs of different area and different climate requirements. ew Point Temperature Energy recovery and mechanical dehumidifier requirements are significantly different based NL on outdoor conditions. N Q In the west, the outdoor condition is generally much lower than the space condition. SK M ON NH Outdoor air can naturally be used for indoor VT W dehumidification, and if provided with an efficient energy recovery device, it can be done at ME MT N OOLER & HUMI OR MN M RY NY significantly reduced operating costs. I S WI RI MI WY In the east, outdoor air can be used part P T I NE NV OH time for dehumidification and the mechanical UT IL IN NJ UNITE O STTES WV dehumidification cycle is only needed for the V KS MO KY E N M higher ambient humidity. With colder temperatures in the north, energy recovery for winter TN Z NM OK S R HOT & HUMIL G operation is easily justified. epending on the MS priorities of the user, a significantly different TX L HI system may be appropriate to maximize energy FL efficiency. Exhaust fan 4

6 Munters Offers ifferent Solutions Four different types of systems are available to meet both the difficult requirements of the natatorium and the diverse climates these buildings may experience. These different solutions can be optimized to provide the best solution from a first cost, life cycle cost, and sustainability perspective. They allow for the optimization of energy savings and performance. Selecting the Right System Where is the building located 2 What are the priorities of the 3 and what is the local climate? system required? What is the system size requirement? Hot and Humid: Southeast U.S. Humid, but with cold winter climate: Northeast U.S. Hot and ry: Southwest U.S. ry, but with cold winter climate: Northwest U.S. System Types and Features. Reliability 2. First 3. Operating 4. Increased Ventilation during most of the year Small - < 5 lbs/hr Medium - > 5 lbs/hr, < 3 lbs/hr Large - > 3 lbs/hr Wringer Pool ryool Pool Ventilation Pool Pool esiccant limate Southeast, Northeast, Southwest, Northwest Southeast, Northeast Southwest, Northwest Southeast, Northeast Priority Reduced compressor runtime for enhanced reliability, Low operating cost, Increased ventilation Low first cost Eliminated compressor runtime for enhanced reliability, Low operating cost, Increased ventilation Reduced compressor runtime for enhanced reliability System Size Small, Medium, Large Small, Medium Small, Medium, Large Medium, Large The system features listed do not outline the extent of the product line availability, rather they outline the features of the systems in competitive environments.see the specific system description on the following pages to see the available capacities of each product. Pump Option Wringer Pool and Ventilation Pool systems are available with the heat pump option to heat the pool water. This options adds an evaporator coil to the exhaust air stream as it leaves the unit to recover the last amount of heat from the building exhaust. This allows the heat pump system to efficiently heat the pool water all year long. The dehumidification cycle is not required to operate and the system is sized based on the energy available in the exhaust air stream. The heat pump is also configurable to provide air heating in the winter whenever sufficient heat is available from the exhaust air stream, and providing very efficient heating of the outside air after it has been preheated by the sensible heat exchanger. EXHUST IR (FTER HX) POOL WTER HETER (ONENSER 2) SROLL OMPRESSOR MIX OF O/, PREHETE Y IR-TO-IR HX, N REIRULTION IR POOL WTER OUT 9ºF (32.2º) POOL WTER IN 8ºF (2.7º) SUPPLY IR HETER (ONENSER ) HETE S/ TO SPE 5

7 Wringer Pool Products escription The Wringer Pool dehumidifier utilizes energy recovery to provide heat recovery in the winter and pre-cool/reheat during the summer. The combination of mechanical dehumidification and outside air dehumidification provides an extremely efficient and reliable dehumidification system. The energy derived from the cooling coils is used to reheat the supply air through a refrigerant reheat coil. uring high outdoor humidity the cooling coil acts as the dehumidifier, using the heat exchanger to minimize energy. When the humidity outside is lower than the desired space condition, the unit brings in more outside air to meet the dehumidification load without the need for the cooling coil or compressor run hours, while the heat exchanger recovers the heat from the exhaust air stream to minimize the heating requirement. The unit modulates the outside air to the minimum position during very cold conditions to minimize energy requirements. In addition, a heat pump option can be added to the exhaust air stream to provide pool water and/or supply air heating to increase overall unit efficiency. OUTSIE IR OOLING OIL Product Features 2 double wall casing Wringer flow & Schematic SENSILE HET EXHNGER EXHUST IR SUPPLY IR RETURN IR State Summer Winter Point FM ºF gr/hr FM ºF gr/hr Return Outside Post Exchanger Post ooling, 9, 9, 9, , 2, 2, 2, E 9, 7 5 9, 5 Sensible counter-flow, cross-flow, and heat pipe heat exchangers with up to 88% efficiency Simple dehumidification and energy recovery modes for easy maintenance and control Outside air dehumidification mode for reduced compressor run hours Increased ventilation throughout many operating hours uilt in building exhaust fan to maintain negative pressure Packaged X, split system X, water cooled X & chilled water options microprocessor controls option Option for % outside air during purge mode Stainless steel drain pans pump air and water heating available as option ETL listed E Wringer apacity hart Unit FM Pool Size (sq. ft.) imensions (in.) L x W x H Weight (lbs.) WR 4 4,, -,5 84 x x 92 4,7 WR,,5-2,25 84 x x 92 7,4 WR 8 8, 2, - 3, 84 x x 92 9, WR 2 2, 3, - 4,5 x 74 x 2 2,7 WR 8 8, 4,5 -,75 32 x 78 x , WR 24 24,, - 9, 44 x 98 x , WR 3 3, 7,5 -, 44 x 4 x 27 32, WR 4 4,, - 44 x 4 x 32 39, WR 5 5, 2, - 8, 44 x 5 x 39 44,

8 ryool Pool Product escription The ryool Pool dehumidifier provides energy efficient dehumidification in a small packaged product at low cost. ondenser heat is recovered from the direct expansion refrigeration system to provide the reactivation energy for the desiccant dehumidification process. The cooling energy of the refrigeration system is used to cool and dehumidify the air prior to entering the desiccant wheel. The hybrid refrigerantdesiccant system provides an efficient dehumidifier by eliminating the overcooling required with a refrigeration only based dehumidifier. The system uses the reactivation fan as the exhaust air fan to maintain negative pressure in the space while further enhancing efficiency and minimizing the unit footprint and cost. RETURN IR MOIST IR TO TMOSPHERE ryool flow & Schematic OOLING OIL State Summer Winter Point FM ºF gr/hr FM ºF gr/hr E Return Post ooling Post esiccant Wheel Outside,,, 4,, ,,, 4,, Product Features ESINT WHEEL Foam injected 2 double wall casing HETE TO 5 F IR OOLE ONENSER OUTSIE IR EXHUST IR SUPPLY IR esiccant enhanced process for lower connected tonnage and lower operating cost Packaged X, split system X, water cooled X and chilled water options oated cooling coils and other critical components microprocessor controls Option for % outside air during purge mode Stainless steel drain pans ETL listed E ryool Pool apacity Unit Maximum FM O Return Minimum Exhaust Maximum Exhaust Tons lbs/hr imensions L x W x H Weight Pounds HU-N 5 HUc-24 HUc-342 HUc-345 HUc-45 HUc-42 HUc-2 HUc-3 HUc-83 HUc-84,,35 2,25 2,7 2,7 2,7 3, 5,4 5,4 7,2,2 2,4 3,4 3,4 4, 4,,, 8, 8, 2,2 3,75 4, 4, 4,5 4,5,, 4, 4, ,,,333,333 2, 2, 2,7,2,5 2,5 3, 3, 4, 4,,, 8, lbs/hr 7 lbs/hr 9 lbs/hr 5 lbs/hr 5 lbs/hr 45 lbs/hr lbs/hr 225 lbs/hr 24 lbs/hr 35 lbs/hr 58 x 43 x 78 x 5 x x 5 x x 5 x x 5 x 93 x 5 x 22 x 8 x 7 22 x 8 x x 9 x x 9 x 8 9 3,5 3,5 3,5 4,25 4,25 5,25 5,25 7, apacity based on F % RH space condition 7

9 Ventilation Pool Products escription The Ventilation Pool unit is an enhanced energy recovery system. The core of the unit is an efficient sensible energy recovery heat exchanger. The chart below shows that outdoor air can be used to provide dehumidification for natatorium environments effectively up to approximately ºF dew point. The outdoor air supply can be modulated to provide the correct dehumidification capacity and to not over-dehumidify when possible. In western or similar climates, the ºF dew point condition is rarely exceeded. This allows the system to maintain the desired space humidity most of the time with no need for mechanical dehumidification. On occasion when it is exceeded the resultant increase in space humidity is small. Temperature and humidity in the space will exceed the design condition for a short period of time, but the trade off is a simplified unit design with no refrigeration system. ooling can be provided with indirect evaporative cooling, enhancing the system performance and efficiency. irect evaporative humidification can be added to the supply air. This will minimize the evaporation rate of the pool and the chemical requirements for pool maintenance. Simple, low operating cost, low maintenance, and improved air quality through increased ventilation make the Ventilation Pool unit an attractive option for natatoriums. Outdoor ification Outside ew Point ºF O FM lbs of H 2 Removed O FM lbs of H 2 Removed O FM ,,,,,,,,,,,,,, , 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, Note: ased on space condition of ºF, % RH. lbs of H 2 Removed,2,89,2,28,85, OUTSIE IR Ventilation flow & Schematic EXHUST IR SENSILE HET EXHNGER E RETURN IR HETING OIL State Summer Winter Point FM ºF gr/hr FM ºF gr/hr E Return Outside Post ing Post Exchanger,5 2, 7, 7,, ,5 2, 2, 2,, Product Features 2 double wall casing Optional indirect evaporative cooling to provide cooling during high ambient temperatures Optional direct evaporative cooling to minimize pool evaporation during low dew point conditions Sensible counter-flow, cross-flow, and heat pipe heat exchangers with up to 88% efficiency Simple dehumidification and energy recovery modes for easy maintenance and control Outside air dehumidification mode eliminating compressors Increased ventilation throughout many operating hours microprocessor controls option Option for % outside air during purge mode pump air and water heating available as option ETL listed 8

10 Pool esiccant Products escription The Pool esiccant unit utilizes a silica gel desiccant dehumidification wheel with gas fired reactivation to provide dehumidification without the need for compressorized refrigeration. ooling coil operation is only required to provide temperature reduction in the space during high ambient temperatures. The wheel turns at a slow. rpm minimizing maintenance. The desiccant process heats and dehumidifies the supply air reducing the heating required in the heating mode. The effect of this process provides low relative humidity inside the unit and therefore reduced corrosion. Great flexibility and reliability are provided in a packaged large capacity unit. MOIST IR TO TMOSPHERE RETURN IR S flow & Schematic ESINT WHEEL HETE TO 25 F POOL HETING OIL GS URNER OOLING OIL OUTSIE IR E F OUTSIE IR State Summer Winter Point FM ºF gr/hr FM ºF gr/hr Return Post esiccant Wheel,, ,, Post ing Post ooling,, , 25, 25 E F Outside Product Features Foam injected 2 double wall casing esiccant dehumidification process for lower connected tonnage and lower compressor run hours Low relative humidity during dehumidification process for reduced corrosion Packaged X, split system X, water cooled X and chilled water options oated cooling coils and other critical components microprocessor controls option Option for % outside air during purge mode Stainless steel drain pans ETL listed Pool esiccant apacity hart Unit Maximum FM O Return Minimum Exhaust Maximum Exhaust Tons lbs/hr imensions L x W x H Weight Pounds S 2 S 3 S 4, 3, 5,, 3, 5, 2, 3, 5, 25 5,, lbs/hr 35 lbs/hr 5 lbs/hr 29 x 8 x 7 29 x 9 x 28 x 34 x,5 8,5,5 9

11 Economic Evaluation and Life ycle Munters has software tools to analyze the operating cost of each system. Unit selection and cost data are inputted with design parameters, local weather data, and energy costs. The output is annual energy cost, annual energy savings, and simple payback. $ vs. $, Operating of Munters Ventilation Pool Product Location FM Required Humidity Ratio Summer Outside Return Temperature Return Relative Humidity ry ulb MW* P Hours.* at ondition hicago, IL. 2,.2 Outside, 7,525 5,9 4,7 4,38 3,934 3,75 3,2 3,392 3,322 3,94 3,98 3,2 2,97 2,843 hange Over ew Point Recovery Effectiveness ooling Fuel of ing Fuel Efficiency of Fuel onversion (ing) Outside FM at hange Over Tons $22 $97 $524 $94 $,88 $,32 ondenser vailable TUH 44,52 45,48 434,84 4,99 38,4 32,83 248, /kwh=$9./Million TU of ooling Input $./,, TU 8 2, Required No to $2 $ $38 $75 $ $ $ $7 $7 $8 $97 $38 $84 $3 $94 $3 $48 $3 $3 $33 ondenser Reheat redit $2 $ $38 $75 $ ooling Equipment.O.P Summer uilding Load Winter uilding Load Max Evaporation Rate X LT ondenser Water redit $. $. $45 $89.7 $4. $ MH 89 MH 98 #/Hr. 5.2 ºF ollars Spent $2. $8. $8.3 $ $,73.22 $, $. $. $9. $7.4 $85. $9.78 $38. $83.99 $35. $93.54 $2.78 $.88 $35.94 $29.7 $32.4 nnual Energy Expense $5,9.4 Operating of onventional Refrigeration-ased Pool ifier as omparison Location FM Required Humidity Ratio Min Outside Return Temperature ry ulb MW* P Hours.* at ondition hicago, IL. 2,.2 Outside Recovery Effectiveness ooling Fuel of ing Fuel Efficiency of Fuel onversion (ing) Return Relative Humidity LT/Tons 2./4.5.5/4.9.9/45.3/43.5.7/ / / / /29.2 /24. / / / / / / / / / / / / $33 $37 $842 $,2 $2,2 $2,853 $2,955 $2,397 $,7 ondenser vailable TUH 8,42 73,89 7,459 52,889 32,94 58,94 53, , ,289 32,57./kwh=$9./Million TU of ooling Input $./,, TU 8 Required No to $ $ $4 $98 $9 $28 $337 $34 $38 $53 $85 $223 $327 $4 $34 $237 $2 $25 $95 $79 $88 ondenser Reheat redit $ $ $4 $98 $9 $28 $337 $34 $374 *Weather data used for hicago, IL. exchanger effectiveness is based on dry sensible heat transfer. ondensing within the heat exchanger will increase performance. ooling Equipment.O.P Summer uilding Load Winter uilding Load Max Evaporation Rate ondenser Water redit $. $. $45.8 $89.7 $34. $35.7 $ MH 3 MH 98 #/Hr. ollars Spent $3.34 $29.5 $79.5 $,5.98 $2,75.7 $2,5.7 $2,89.2 $2, $, $53. $84.55 $ $327.4 $44. $ $237.8 $2.5 $25.29 $95.4 $79. $88.48 nnual Energy Expense $,7.4

12 Operating of Wringer Pool Product Location Washington FM 2, Required Humidity Ratio.2 Summer Outside Return Temperature Return Relative Humidity ry ulb MW* P Hours.* at ondition Outside,,9 5,325 4,58 4,75 3,78 3,25 3,492 3,295 3,52 3,7 3,3 3,2 2,97 2,843 hange Over ew Point Recovery Effectiveness ooling Fuel of ing Fuel Efficiency of Fuel onversion (ing) Outside FM at hange Over Tons $29 $324 $998 $,598 $2,3 $2,85 ondenser vailable TUH /kwh=$9./Million TU of ooling Output $./,, TU 8 2, Required No F to $ $8 $3 $59 $97 $57 $ $7 $79 $88 $ $23 $33 $29 $ $52 $27 $4 $4 ondenser Reheat redit $ $8 $3 $59 $97 $57 ooling Equipment.O.P Summer uilding Load Winter uilding Load Max Evaporation Rate X LT ondenser Water redit 3 MH 2 MH 98 #/Hr ºF ollars Spent $29.4 $324. $ $,598. $2,3.2 $2,85.2 $.48 $75.73 $79. $87.98 $.24 $23.42 $33.2 $29.5 $8.8 $5. $2. $4.49 $ nnual Energy Expense $8,87.54 Operating of onventional Refrigeration-ased Pool ifier as omparison Location Washington FM 2, Required Humidity Ratio.2 Min Outside Return Temperature ry ulb MW* P Hours.* at ondition Outside Recovery Effectiveness ooling Fuel of ing Fuel Efficiency of Fuel onversion (ing) Return Relative Humidity Tons 2./4.5.5/4.9.9/45.3/43.5.7/42. 2/4 2.2/4. 3.9/ /27.4.4/22.5 / / / / / / / / / / / / $33 $38 $,24 $2, $3,34 $4,3 $3,34 $2,42 $,2 ondenser vailable TUH 8,42 73,89 7,459 52,889 32,94 5,35,57 498,342 4, ,87./kwh=$9./Million TU of ooling Input $./,, TU 8 Required No F *Weather data used for Washington,. exchanger effectiveness is based on dry sensible heat transfer. ondensing within the heat exchanger will increase performance. to $ $4 $ $29 $22 $385 $38 $3 $357 $ $27 $289 $32 $39 $29 $35 $7 $39 $ $ ondenser Reheat redit $ $4 $ $29 $22 $385 $38 $3 $29 ooling Equipment.O.P Summer uilding Load Winter uilding Load Max Evaporation Rate ondenser Water redit $. $9.93 $7.25 $8.49 $74.9 $25.8 $53.4 $ MH 3 MH 98 #/Hr. ollars Spent $3.34 $3.2 $,.33 $,997.3 $2,859.2 $4,9.29 $3,87.39 $2, $,887. $.25 $27.2 $285. $39. $39.23 $28.7 $35. $7.85 $38.9 $ nnual Energy Expense $9,.7 $8, vs. $9, This two-page comparison allows the designer and end user to make intelligent decisions regarding system configuration and payback criteria. Together, Munters can assist in selecting the correct systems and options to meet the customers needs and desires.

13 Munters Flexibility Natatoriums vary in size, shape, and location. Some are low, small rooms, others are atriums of hotels with vast deck areas and high ceilings. Some are totally interior with no transmission load, while others are completely enclosed in glass with large transmission loads. Munters provides a standard or customized product for precise application for any amount and proportion of sensible and latent capacity to meet the load. Munters provides systems with increased outside air throughout the year to improve indoor air quality, while reducing the air to minimum required airflows during extreme temperatures to minimize operating cost. 9 Jordan Road Selma, TX 7854 Tel: or Fax: G 3 Rev. 9, 3/8