D-PAC Functionality Factory Testing Ease of Installation Ease of Maintenance Energy Efficiency

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Digital Precise Air Control System D-PAC Functionality Factory Testing Ease of Installation Ease of Maintenance Energy Efficiency

AAON • 2425 South Yukon Avenue • Tulsa, Oklahoma 74107 • (918) 583-2266 • Fax (918) 583-6094 • www.aaon.com Total Control Indoor Air Quality and Comfort ndoor air quality (IAQ) and occupant comfort are two of the most Scroll compressor, return important factors to consider with any HVAC system design. One air bypass, and modulating ofI the leading causes of poor IAQ and occupant discomfort is too hot gas reheat for energy much moisture in the air, commonly referred to as high humidity. efficient load matching IAQ problems associated with high humidity include mold growth, humidity control. An AAON condensation and increased sickness and allergic reactions. As for D-PAC controller is also occupant comfort, the saying goes “It’s not the heat, it’s the humidity”. factory installed to provide Improving indoor air quality and occupant comfort by controlling optimum performance of the the humidity and the temperature will help with these problems, system. Thus, the D-PAC boost productivity, and even improve the general well-being of the system provides an energy occupants. efficient, cost effective solution for temperature One way to improve IAQ and occupant comfort is with uniform and humidity control. humidity and temperature control. Ideally indoor conditions should remain consistently around 75°F dry bulb and 45% relative humidity. This will keep the occupants comfortable and decrease the likelihood The Competition of IAQ issues. ome in the HVAC industry assume that as Energy Use theS dry bulb temperature ontrolling both temperature and humidity can be very energy is being controlled the intensive. This is because both the sensible (temperature) and humidity will be controlled Clatent (humidity) loads require energy from the HVAC equipment to as well. This, however, is be controlled. With a conventional rooftop unit extra energy is used to not true at many ambient satisfy the sensible load during part load conditions because cooling is conditions and space loads staged with only a few compressors which will not always match the with higher humidity. load. To satisfy the latent load the system must either satisfy the latent Humidity is also especially load while satisfying the sensible load, include an energy recovery uncontrollable when in wheel to reduce the outside air load, or there must be some form of ventilation mode, when cooling and reheating to dehumidify the air and avoid overcooling the the mechanical cooling is space. Satisfying the latent load while satisfying the sensible load and off and outside air is being including an energy recovery wheel will not control the humidity at introduced into the system. all conditions. Cooling and reheating will control the humidity at all Previously there have been conditions, however, it uses extra energy. only a few solutions for controlling both temperature The Solution and humidity. he AAON energy efficient rooftop unit solution to improving One method is to have a indoor air quality and occupant comfort by controlling both chiller and boiler system temperatureT and humidity is the patented Digital Precise Air Control with air handling units. This System, D-PAC (Patent No. 6,792,767). method allows modulation The system uses a Digital Scroll™ compressor, with modulating of both cooling and capacity control, for energy efficient load matching temperature control. reheating for tight control of For humidity control the system uses a combination of the Digital temperature and humidity.

2 The D-PAC System

The problems with this system are that it is large, expensive to implement, and energy is wasted controlling the humidity because both the chillers and boilers must be running. Figure 1: Loaded State Figure 2: Unloaded State The second solution is a conventional rooftop unit with on/off hot gas reheat. What is D-PAC? The problems with this he D-PAC control system consists of a Digital Scroll compressor, system are there is poor modulating hot gas reheat, an economizer with three independently control of the amount controlledT sections - outside air, return air, and return air bypass - and an of reheat, there will be AAON D-PAC controller. uncomfortable discharge air temperature swings during The Digital Scroll Compressor varies the volume of refrigerant that operation, especially in flows through the cooling system. This allows the compressor to match make up air applications, the load needed by the unit. The compressor can modulate from 10-100% and finally the temperature of its cooling capacity. This allows the unit to have tighter temperature is still only controlled by a control than a conventional few compressor stages. unit. The compressor will 16 Digital Scroll 14 also run for a longer period r 12.8 so es The last solution is to use pr m of time, dehumidifying the 12 o C y 10.4 an energy recovery wheel it c air more and cycling the a 10 p a rd to control humidity. This, C da le n compressor on and off less. b ta 8 ia S r or however, is not a total a ss V pre 6 om y C solution because at higher The compressor operates cit pa Ca 4 d xe latent loads humidity will in two states, loaded and Fi Energy EciencyEnergy Ratio still be an issue. unloaded, to be able to 2 % modulate from 10-100 0 Reduced Load & Maximum Load & (Figure 1 and 2). The loaded Ambient Temperature Ambient Temperature

state is the standard scroll Figure 3: Unit with a Digital Scroll compressor compressor operation. compared to a unit with a fixed capacity scroll During the unloaded state compressor and hot gas bypass. a solenoid valve opens and the top of the scroll moves up separating from the bottom of the scroll allowing refrigerant to circulate back to the suction line and keeping it from leaving out the discharge line. There is a power reduction during this unloaded state that allows the compressor and unit to save energy at part Digital Scroll  load conditions (Figure 3). By pulsing between the loaded and unloaded Compressor states the capacity of the compressor can be varied for energy saving load matching capability.

3 Evaporator Mixed Air (MA) The Return Air Bypass Reheat Coil Coil Filters feature consists of an economizer with three independently controlled sections - outside air, return air, and return air bypass (Figure 4). The outside air damper routes all of the Outside Air (OA) ventilation air through the evaporator coil. The return Return Air Bypass air damper routes return Economizer air through the evaporator coil. The return air bypass damper routes up to 50% of the return air around the Supply Air after Return Air Bypass Cooling Coil Return Air (RA) evaporator coil. This allows and Modulating Hot Gas Reheat Leaving Air (CCLA) the mixed return and outside (RAB + MHGR) air to be dehumidified by the evaporator coil and Figure 4: D-PAC Airflow then reheated by the return air bypassed around the The Modulating Hot Gas Reheat feature coil. The cooling load is consists of a reheat coil downstream of the increased when return air is evaporator coil, a modulating reheat hot bypassed because the mixed gas valve, a modulating condenser hot gas air entering the evaporator valve, and a reheat controller (Figure 5). The coil contains a greater evaporator coil cools the mixed air to below percentage of outside air; the the dew point and then reheats the air with mixed air is not pre-cooled the reheat coil. The modulating valves allow by the bypassed return air. only the needed amount of reheat to be used, Return air bypass is an creating consistent supply air temperature. To energy efficient solution to minimize energy usage, reheat begins only controlling light humidity after the return air bypass damper is fully loads. open with the D-PAC System. Modulating hot Modulating Hot Gas gas reheat is an energy efficient solution to Reheat Control Valve controlling high humidity loads. The AAON D-PAC Controller controls the fans, outside air, return air, and return air bypass actuators, modulating hot gas reheat, compressors, heating, and optional AAONAIRE® energy recovery wheel. Using these components, the controller controls the temperature and humidity of the space under all conditions in the most energy efficient manner. The controller is factory installed and tested to ensure proper operation. The WattMaster WattMaster VCM-X controller and the AAON JENEsys controller are VCM-X Controller available for the D-PAC system to meet any controls application. With a choice of these factory installed controllers a D-PAC unit can used as a stand alone unit or integrated into an existing building automation system. The factory installed and tested D-PAC unit controller optimizes performance of the complete D-PAC system.

AAON JENEsys Controller

4 Why Use a Digital Scroll Compressor? Sequence of Operation There four common ways to modulate the refrigerant capacity of a s the space temperature cooling system: hot gas bypass, multiple compressors, an inverter driven Aincreases or decreases, compressor and a Digital Scroll compressor. the controller modulates A hot gas bypass system mixes hot refrigerant gas from the compressor the compressor’s capacity with cool refrigerant liquid at the evaporator to control the cooling capacity. to maintain the space Hot gas bypass is an inefficient modulation technique because it is adding temperature setpoint. a false load that the system must satisfy. As the space humidity rises, A multiple compressor system stages the compressors on and off to the controller modulates control the cooling capacity. The problem with this system is that it has the compressors capacity to a finite number of capacity steps for modulation and will have inefficient maintain a low evaporator operation at many part load conditions. Another issue is at smaller tonnages coil temperature to maximize multiple compressors are often not available. dehumidification and meet the space latent load. The An inverter driven compressor system varies the speed of the compressor controller then modulates motor to control the cooling capacity. This system, however, has oil return the return air damper closed issues and the modulation range is limited by the motor speed range. and the return air bypass A Digital Scroll compressor system modulates the volume of refrigerant damper open, diverting that flows through the cooling system to control the cooling capacity. It is a return air around the simple, reliable, energy efficient system with wide modulation capability. evaporator coil to maintain the space temperature. Humidistat After the return air bypass (Factory or Field Supplied Accessory) damper is fully open, the controller uses modulating hot gas reheat to increase Space the dehumidification capacity of the unit while still maintaining the space temperature. Thus, the TXV humidity setpoint and temperature setpoint will be Supply Fan Reheat Evap maintained with minimum Coil Coil

Supply Air energy usage. Temp Sensor (Factory Provided)

Field Reheat Wiring Check Hot Gas Reheat Controller Valve Valve Flow Flow

Optional Reset Signal (Field Provided) Condenser Receiver Tank

Figure 5: Modulating Hot Gas Reheat

5 System Comparison Full load Rooftop Unit with Modulating Hot Gas Reheat Example1: e x a m p l e With the addition of modulating hot gas reheat the unit can consisting of a large well lit conference control to the desired conditions of 75°F DB space temperature room with occupants, laptops, projectors and 45% space relative humidity. The amount of reheat required and other sensible heat sources. is 33.1 MBtu/h. The load on the compressor is 9.8 tons, thus a modulating hot gas reheat, 10 ton rooftop unit is required. Ambient conditions are 95°F DB and Controlling the humidity with modulating hot gas reheat alone 75°F WB with 2,800 cfm of supply air, required an extra 3.8 tons of load. 700 cfm of outside air and 700 cfm of exhaust air. A packaged rooftop unit is Rooftop Unit with a Digital Scroll Compressor, Return Air attempting to control to 75°F DB space Bypass and Modulating Hot Gas Reheat (D-PAC) % temperature and 45 space relative With the addition of a Digital Scroll compressor, return air humidity. The space full load conditions bypass and modulating hot gas reheat the unit can control to are 40 MBtu/h sensible load and 10 the desired conditions of 75°F DB space temperature and 45% MBtu/h latent load for a sensible heat space relative humidity. The load on the compressor is 7.8 tons, ratio of 0.8. Supply fan motor heat is thus a D-PAC, 8 ton rooftop unit is required. Controlling the neglected. Psychrometric charts match humidity with the D-PAC unit required an extra 1.8 tons of with the descriptions. Calculations load, over the conventional rooftop with uncontrolled humidity. can be recreated using your specific % ambient and loading conditions within The D-PAC unit can control to 45 space relative humidity and the AAONEcat32TM software. requires 2 tons less load than the modulating hot gas reheat only unit. Conventional Rooftop Unit D-PAC with an AAONAIRE Sensible Energy Recovery Wheel With no humidity control the conventional rooftop unit can control With the addition of an AAONAIRE sensible energy recovery to 75°F DB space temperature with wheel the unit can control to the desired conditions of 75°F % an uncontrolled 65% space relative DB space temperature and 45 space relative humidity. The humidity. The load on the compressor addition of the sensible energy recovery wheel reduced the is 6.0 tons, thus a 6 ton rooftop unit is entering outside air conditions to 79°F DB and 70°F WB. The required. load on the compressor is 6.7 tons, thus a sensible AAONAIRE, D-PAC, 7 ton rooftop unit is required. Therefore, the D-PAC Rooftop Unit with Return Air Bypass unit with an AAONAIRE sensible energy recovery wheel With the addition of return air bypass requires 1.1 tons less than a D-PAC unit alone. the unit can control to the conditions D-PAC with an AAONAIRE Total (Enthalpy) Energy Recovery of 75°F DB space temperature and Wheel 53% space relative humidity. Return air bypassed around the evaporator coil is With the addition of an AAONAIRE total energy recovery 1,050 cfm. The load on the compressor wheel the unit can control to the desired conditions of 75°F % increased to 6.7 tons because the mixed DB space temperature and 45 space relative humidity. The air entering the evaporator coil is not addition of the total energy recovery wheel reduced the entering pre-cooled by the bypassed return air, outside air conditions to 79°F DB and 65°F WB. The load on thus a return air bypass 7 ton rooftop unit the compressor is 5.6 tons, thus a total AAONAIRE, D-PAC, is required. Controlling the humidity 6 ton rooftop unit is required. Therefore, the D-PAC unit with with return air bypass alone required an an AAONAIRE total energy recovery wheel requires 2.2 tons extra 0.7 tons of load, however, the unit less than a D-PAC unit alone. It requires the same tonnage as cannot control to 45% relative humidity the conventional unit and controls both temperature and because only up to 50% of the total humidity! return air can be bypassed.

6 Psychrometric Chart Comparisons

80 80 40 40 140 140 0.45 0.45

130 130

0.40 0.40 120 120 75 WET BULB TEMPERATURE 75 WET BULB TEMPER 35 35

110 110 ATURE - °F 0.35 0.35 - °F

OA 100 OA 100 70 70 30 30

MA 90 0.30 90 0.30

14.0 VOLUME- CU.FT. PER LB. DRY AIR 14.0 VOLUME- CU.FT. PER LB. DRY AIR 65 65 80 80

RA 0.25 0.25 25 25 MA CCLA 70 70 60 60 VAPOR PRESSURE - PSIA VAPOR PRESSURE - PSIA 25% 0.20 25% 0.20 90% 60 90% RA 60 20 55 20 55 RAB 80% CCLA80% WET BULB, DEW POINT, SATURATION TEMP - °F 50 WET BULB, DEW POINT, SATURATION TEMP - °F 50

5070% 0.15 5070% 0.15

60% 40 60% 40 15 45 15 45 15% 15% 50% 50% 40 30 0.10 40 30 0.10 13.0 13.0 40% 40%

30% 8% RELATIVE HUMIDITY 20 30% 8% RELATIVE HUMIDITY 20

6% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND DRY AIR 0.05 6% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND DRY AIR 0.05 20% 20% 4% 10 4% 10 10% RELATIVE HUMIDITY 10% RELATIVE HUMIDITY 10 2% 10 2%

40 45 50 55 60 65 70 75 80 85 90 95 100 105 40 45 50 55 60 65 70 75 80 85 90 95 100 105 DRY BULB TEMPERATURE - °F DRY BULB TEMPERATURE - °F

Full Load Conventional Full Load with Return Air Bypass

80 80 40 40 140 140 0.45 0.45

130 130

0.40 0.40 120 120 75 WET BULB TEMPERATURE - °F 75 WET BULB TEMPERATURE - °F 35 35

110 110 0.35 0.35

OA 100 OA 100 70 70 30 30

90 0.30 90 0.30

14.0 VOLUME- CU.FT. PER LB. DRY AIR 14.0 VOLUME- CU.FT. PER LB. DRY AIR 65 65 80 80

0.25 0.25 25 25

70 70 60 60 MA VAPOR PRESSURE - PSIA VAPOR PRESSURE - PSIA MA 25% 0.20 25% 0.20 90% 60 90% 60

20 55 20 55 80% 80% WET BULB, DEW POINT, SATURATION TEMP - °F RA 50 WET BULB, DEW POINT, SATURATION TEMP - °F RA 50 CCLA 5070% MHGR 0.15 CCLA 5070% RAB MHGR 0.15 60% 40 60% 40 15 45 15 45 15% 15% 50% 50% 40 30 0.10 40 30 0.10 13.0 13.0 40% 40%

30% 8% RELATIVE HUMIDITY 20 30% 8% RELATIVE HUMIDITY 20

6% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND DRY AIR 0.05 6% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND DRY AIR 0.05 20% 20% 4% 10 4% 10 10% RELATIVE HUMIDITY 10% RELATIVE HUMIDITY 10 2% 10 2%

40 45 50 55 60 65 70 75 80 85 90 95 100 105 40 45 50 55 60 65 70 75 80 85 90 95 100 105 DRY BULB TEMPERATURE - °F DRY BULB TEMPERATURE - °F

Full Load with Modulating Hot Gas Reheat Full Load D-PAC

80 80 40 40 140 140 0.45 0.45

130 130

0.40 0.40 120 120 75 WET BULB TEMPERATURE - °F 75 WET BULB TEMPERATURE - °F 35 35

110 110 0.35 0.35

S-ERW OA 100 OA 100 70 70 30 30

90 0.30 90 0.30

14.0 VOLUME- CU.FT. PER LB. DRY AIR 14.0 VOLUME- CU.FT. PER LB. DRY AIR 65 65 80 80

0.25 0.25 25 MA 25 T-ERW 70 70 60 60 VAPOR PRESSURE - PSIA VAPOR PRESSURE - PSIA 25% 0.20 25% 0.20 90% 60 90% 60 20 55 20 55 MA 80% 80% WET BULB, DEW POINT, SATURATION TEMP - °F RA 50 WET BULB, DEW POINT, SATURATION TEMP - °F RA 50 CCLA 5070% RAB MHGR 0.15 CCLA 5070% RAB MHGR 0.15 60% 40 60% 40 15 45 15 45 15% 15% 50% 50% 40 30 0.10 40 30 0.10 13.0 13.0 40% 40%

30% 8% RELATIVE HUMIDITY 20 30% 8% RELATIVE HUMIDITY 20

6% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND DRY AIR 0.05 6% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND DRY AIR 0.05 20% 20% 4% 10 4% 10 10% RELATIVE HUMIDITY 10% RELATIVE HUMIDITY 10 2% 10 2%

40 45 50 55 60 65 70 75 80 85 90 95 100 105 40 45 50 55 60 65 70 75 80 85 90 95 100 105 DRY BULB TEMPERATURE - °F DRY BULB TEMPERATURE - °F

Full Load D-PAC with Sensible Energy Recovery Wheel Full Load D-PAC with Total Energy Recovery Wheel

OA = Outside Air or outside air after going through the wheel; S-ERW = Preconditioned outside air downstream of the Sensible Energy Recovery Wheel; T-ERW = Preconditioned outside air downstream of the Total Energy Recovery Wheel; RA = Return Air; MA = Mixed Air (Return and outside air); CCLA = Cooling Coil Leaving Air before mixing with bypassed return air and before reheat coil; SA = Supply Air

7 Part load Rooftop Unit with Return Air Bypass Example2: e x a m p l e With the addition of return air bypass the unit can control to consisting of the same conference room the conditions of 75°F DB space temperature and 86% space in the full load example with the lights relative humidity. Return air bypassed around the evaporator and electronics turned off while the coil is 1,050 cfm. The load on the compressor increased to occupants are watching a video on a 2.4 tons because the mixed air entering the evaporator coil projection screen. is not pre-cooled by the bypassed return air. Controlling the humidity with return air bypass alone required an extra 0.2 Ambient conditions are 95°F DB and tons of load, however, the unit cannot control to 45% relative 75°F WB with 2,800 cfm of supply air, humidity because only up to 50% of the total return air can be 700 cfm of outside air and 700 cfm of bypassed. exhaust air. A packaged rooftop unit is attempting to control to 75°F DB space Rooftop Unit with Modulating Hot Gas Reheat % temperature and 45 space relative With the addition of modulating hot gas reheat the unit humidity. The space part load conditions can control to the desired conditions of 75°F DB space are 10 MBtu/h sensible load and 10 temperature and 45% space relative humidity. The amount of MBtu/h latent load for a sensible heat reheat required is 63.1 MBtu/h. The load on the compressor ratio of 0.5. Supply fan motor heat is increased to 9.8 tons because the mixed air is cooled to below neglected. Psychrometric charts match the dew point and then reheated. Controlling the humidity with the descriptions. Calculations can with modulating hot gas reheat alone required an extra 7.6 be recreated using your specific ambient tons of load. and loading conditions within the AAONEcat32TM software. Rooftop Unit with a Digital Scroll Compressor, Return Air Bypass and Modulating Hot Gas Reheat (D-PAC) Conventional Rooftop Unit With the addition of a Digital Scroll compressor, return air With no humidity control the conventional bypass and modulating hot gas reheat the unit can control to rooftop unit can control to 75°F DB the desired conditions of 75°F DB space temperature and 45% space temperature with an uncontrolled space relative humidity. The load on the compressor is 7.8 % 89 space relative humidity. The load on tons. Controlling the humidity with the D-PAC unit required the compressor is 2.2 tons. an extra 5.6 tons of load. The D-PAC unit can control to 45% space relative humidity and requires 2 tons less load than the modulating hot gas reheat only unit. Note: By adding a Digital Scroll D-PAC with an AAONAIRE Sensible compressor to a conventional rooftop unit, the compressor Energy Recovery Wheel work will be greatly reduced With the addition of an AAONAIRE sensible energy recovery at part load conditions because wheel the unit can control to the desired conditions of 75°F the compressor can match the DB space temperature and 45% space relative humidity. The required load. The Digital Scroll addition of the sensible energy recovery wheel reduced the compressor will also cycle on and entering outside air conditions to 79°F DB and 70°F WB. The off less resulting in less compressor load on the compressor is 6.7 tons. Therefore, the D-PAC unit wear, tighter temperature control, with an AAONAIRE sensible energy recovery wheel requires more dehumidification, and longer compressor life. 1.1 tons less than a D-PAC unit alone. D-PAC with an AAONAIRE Total (Enthalpy) Energy Recovery Wheel With the addition of an AAONAIRE total energy recovery wheel the unit can control to the desired conditions of 75°F DB space temperature and 45% space relative humidity. The addition of the total energy recovery wheel reduced the entering outside air conditions to 79°F DB and 65°F WB. The load on the compressor is 5.6 tons. Therefore, the D-PAC unit with an AAONAIRE total energy recovery wheel requires 2.2 tons less than a D-PAC unit alone. 8 Psychrometric Chart Comparisons

80 80 40 40 140 140 0.45 0.45

130 130

0.40 0.40 120 120 RA 75 WET BULB TEMPERATURE 75 WET BULB TEMPER 35 MA 35 RA 110 RAB 110 MA ATURE - °F 0.35 0.35 CCLA - °F OA 100 OA 100 70 70 30 30 CCLA

90 0.30 90 0.30

14.0 VOLUME- CU.FT. PER LB. DRY AIR 14.0 VOLUME- CU.FT. PER LB. DRY AIR 65 65 80 80

0.25 0.25 25 25

70 70 60 60 VAPOR PRESSURE - PSIA VAPOR PRESSURE - PSIA 25% 0.20 25% 0.20 90% 60 90% 60

20 55 20 55 80% 80% WET BULB, DEW POINT, SATURATION TEMP - °F 50 WET BULB, DEW POINT, SATURATION TEMP - °F 50

5070% 0.15 5070% 0.15

60% 40 60% 40 15 45 15 45 15% 15% 50% 50% 40 30 0.10 40 30 0.10 13.0 13.0 40% 40%

30% 8% RELATIVE HUMIDITY 20 30% 8% RELATIVE HUMIDITY 20

6% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND DRY AIR 0.05 6% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND DRY AIR 0.05 20% 20% 4% 10 4% 10 10% RELATIVE HUMIDITY 10% RELATIVE HUMIDITY 10 2% 10 2%

40 45 50 55 60 65 70 75 80 85 90 95 100 105 40 45 50 55 60 65 70 75 80 85 90 95 100 105 DRY BULB TEMPERATURE - °F DRY BULB TEMPERATURE - °F

Part Load Conventional Part Load with Return Air Bypass

80 80 40 40 140 140 0.45 0.45

130 130

0.40 0.40 120 120 75 WET BULB TEMPERATURE - °F 75 WET BULB TEMPERATURE - °F 35 35

110 110 0.35 0.35

OA 100 OA 100 70 70 30 30

90 0.30 90 0.30

14.0 VOLUME- CU.FT. PER LB. DRY AIR 14.0 VOLUME- CU.FT. PER LB. DRY AIR 65 65 80 80

0.25 0.25 25 25

70 70 60 60 MA VAPOR PRESSURE - PSIA VAPOR PRESSURE - PSIA MA 25% 60 0.20 25% 60 0.20 90% 90%

20 55 20 RAB55 80% 80% WET BULB, DEW POINT, SATURATION TEMP - °F RA 50 WET BULB, DEW POINT, SATURATION TEMP - °F RA 50 CCLA 5070% MHGR 0.15 CCLA 5070% MHGR 0.15 60% 40 60% 40 15 45 15 45 15% 15% 50% 50% 40 30 0.10 40 30 0.10 13.0 13.0 40% 40%

30% 8% RELATIVE HUMIDITY 20 30% 8% RELATIVE HUMIDITY 20

6% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND DRY AIR 0.05 6% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND DRY AIR 0.05 20% 20% 4% 10 4% 10 10% RELATIVE HUMIDITY 10% RELATIVE HUMIDITY 10 2% 10 2%

40 45 50 55 60 65 70 75 80 85 90 95 100 105 40 45 50 55 60 65 70 75 80 85 90 95 100 105 DRY BULB TEMPERATURE - °F DRY BULB TEMPERATURE - °F

Part Load with Modulating Hot Gas Reheat Part Load D-PAC

80 80 40 40 140 140 0.45 0.45

130 130

0.40 0.40 120 120 75 WET BULB TEMPERATURE - °F 75 WET BULB TEMPERATURE - °F 35 35

110 110 0.35 0.35

S-ERW OA 100 OA 100 70 70 30 30

90 0.30 90 0.30

14.0 VOLUME- CU.FT. PER LB. DRY AIR 14.0 VOLUME- CU.FT. PER LB. DRY AIR 65 65 80 80

0.25 0.25 25 MA 25 T-ERW 70 70 60 60 VAPOR PRESSURE - PSIA VAPOR PRESSURE - PSIA 25% 60 0.20 MA 25% 60 0.20 90% 90%

20 55 RA 20 55 80% 80% WET BULB, DEW POINT, SATURATION TEMP - °F 50 WET BULB, DEW POINT, SATURATION TEMP - °F RA 50 CCLA 5070% RAB MHGR 0.15 CCLA 5070% RAB MHGR 0.15 60% 40 60% 40 15 45 15 45 15% 15% 50% 50% 40 30 0.10 40 30 0.10 13.0 13.0 40% 40%

30% 8% RELATIVE HUMIDITY 20 30% 8% RELATIVE HUMIDITY 20

6% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND DRY AIR 0.05 6% HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND DRY AIR 0.05 20% 20% 4% 10 4% 10 10% RELATIVE HUMIDITY 10% RELATIVE HUMIDITY 10 2% 10 2%

40 45 50 55 60 65 70 75 80 85 90 95 100 105 40 45 50 55 60 65 70 75 80 85 90 95 100 105 DRY BULB TEMPERATURE - °F DRY BULB TEMPERATURE - °F

Part Load D-PAC with Sensible Energy Recovery Wheel Part Load D-PAC with Total Energy Recovery Wheel

9 System Comparison Summary Return Air Bypass alone can control humidity at high sensible heat ratio loads. Modulating Hot Gas Reheat alone can control humidity at a majority of load conditions, however, a larger unit with more capacity may be needed. D-PAC (Digital Scroll Compressor, Return Air Bypass and Modulating Hot Gas Reheat) can control humidity and temperature at all load conditions. It can also control humidity at those conditions with less compressor work than modulating hot gas reheat alone. AAONAIRE Energy Recovery Wheel can greatly reduce the compressor work at all load conditions. Thus, the overall size of the unit can be reduced resulting is less initial and running cost.

Full Load Steady State Conditions Supply Return Air Space Space Air Compressor Reheat Bypass DB RH DB Load Amount Amount Controlling Temperature Only Conventional System 75°F 65% 62°F 6.0 tons NA NA Controlling Temperature and Humidity With Only Return Air Bypass 53% 6.7 tons NA 1,050 cfm (RAB) With Only Modulating Hot Gas 9.8 tons 33,100 Btu/h NA Reheat (MHGR) With a Digital Scroll, RAB and 75°F 62°F 7.8 tons MHGR (D-PAC) 45% D-PAC with Sensible Energy 6.7 tons 8,800 Btu/h 1,050 cfm Recovery Wheel D-PAC with Total (Enthalpy) 5.6 tons Energy Recovery Wheel

Part Load Steady State Conditions Supply Return Air Space Space Air Compressor Reheat Bypass DB RH DB Load Amount Amount Controlling Temperature Only Conventional System 75°F 89% 72°F 2.2 tons NA NA Controlling Temperature and Humidity With Only Return Air Bypass 84% 2.4 tons NA 1,050 cfm (RAB) With Only Modulating Hot Gas 9.8 tons 63,100 Btu/h NA Reheat (MHGR) With a Digital Scroll, RAB and 75°F 72°F 7.8 tons MHGR (D-PAC) 45% D-PAC with Sensible Energy 6.7 tons 38,800 Btu/h 1,050 cfm Recovery Wheel D-PAC with Total (Enthalpy) 5.6 tons Energy Recovery Wheel

10 Conclusion The D-PAC control system combines a Digital Scroll compressor, return air bypass, and modulating hot gas reheat to control both space temperature and space humidity. With the combination of these components, and an AAON D-PAC controller to optimize them, the system can control temperature and humidity as efficiently as possible. The system can accurately control the temperature to +/- 1°F and the relative humidity to +/- 5%. The patented sequence of operation allows the unit to have reduced energy costs when compared to conventional temperature and humidity control systems.

Applications for the D-PAC system, which require both temperature and humidity control, include supermarkets, convenience stores, schools, office buildings, restaurants, cafes, churches, auditoriums, health clubs, healthcare facilities, lodgings, museums and libraries.

Contact your local AAON Sales representative to learn more about the AAON D-PAC features and many more ways AAON can provide HVAC solutions to your applications.

Winners of... The D-PAC control system was recognized as the 2008 Product of the Year, in the HVAC category, and the Most Valuable Product (MVP), in the overall competition, by Consulting-Specifying Engineer Magazine as well as the 2009 Product of the Year by the National Society of Professional Engineers (NSPE).

11 Dening Quality. Building Comfort.

It is the intent of AAON to provide accurate and current product information. However, in the interest of product improvement, AAON reserves the right to change pricing, specifications, and/or design of its product without notice, obligation, or liability. Copyright © AAON, all rights reserved throughout the world. AAON and AAONAIRE are registered trademarks of AAON, Inc., Tulsa, OK.

Functionality Factory Testing Ease of Installation Ease of Maintenance Energy Efficiency

AAON • 2425 South Yukon Avenue • Tulsa, Oklahoma 74107 • (918) 583-2266 • Fax (918) 583-6094 • www.aaon.com

D-Pac • R58460 • 110914