York ECO HFC-410A User Manual

York ECO HFC-410A User Manual Manual pdf 10 page image

JOHNSON CONTROLS10FORM 100.50-EG5 (108)Application Data (continued)VAV SUPPLY AIR PRESSURE CONTROLTraditional packaged rooftop systems use inlet guidevanes (IGVs) for duct static pressure control. Thesecontrol supply duct pressure by modulating dampers(introducing losses and inefficiencies) on the inlet of thefan, open and closed. YORK’s variable frequency drives(VFDs) offer superior fan speed control and quieter,energy efficient operation.For VAV applications, the YORK Eco 2 unit uses a VFDto modulate fan speed and maintain a constant ductstatic pressure. VFDs offer superior control over theoperation of the unit at part load, and offer the additionalbenefits of quieter and more efficient operation whencompared to IGV.HARSH ENVIRONMENTS – CONDENSER ANDEVAPORATOR COIL PROTECTIONFor harsh environmental conditions such as seashoreapplications, YORK offers three types of coil protection:copper fin material, black fin and Technicoat coatings.YORK recommends that for corrosive environments thatcopper fins be used to protect the evaporator and/orcondenser coils. In areas where chemicals that cancorrode copper are present, such as ammonia, YORKrecommends that the black fin or Technicoat coating beused for maximum protection.• Copper-Fin Evaporator and Condenser Coil– Copper fins can be used instead of aluminum foradditional corrosion protection. However, it is notsuitable for areas that are subject to acid rain orexposed to ammonia.• Pre-Coated Condenser Fins – Black fin coating(yellow fin for evaporator fins) is pre-coated appli-cation epoxy on aluminum fin stock to guard fromcorrosive agents and insulate against galvanicpotential. It is used for mild seashore or industriallocations. This can provide corrosion resistancecomparable to copper fin coils in typical seashorelocations.• Post-Coated Condenser Fins – Technicoat (apost-coated application of epoxy) can be used forseashore and other corrosive applications with theexception of strong alkaloides, oxidizers, wet bro-mide, chlorine and fluorine in concentrations greaterthan 100 ppm. Any of the above suitable optionsshould be selected based on the particular projectdesign parameters and related environmental fac-tors. The application should be further reviewed andapproved by the consulting engineer or owner basedon their knowledge of the job site conditions.BUILDING PRESSURE CONTROL SYSTEMSBuilding pressure control systems are often neces-sary when economizers are used to bring in outdoorair. Without proper building exhaust, the building maybecome over pressurized. The pressure control systemmaintains the proper building pressure by expelling theappropriate amount of air from the building.Exhaust/relief fans – In this application, a poweredexhaust fan may be suitable, however careful consid-eration of the fan type is necessary. YORK offers acentrifugal powered exhaust fan to perform this function.Some manufacturers use a propeller exhaust fan, whichcannot handle the static pressure requirements.For systems with moderate to low return static pressure,an exhaust fan is recommended. The benefit of the ex-haust fan is that it does not run all of the time, and mayfacilitate compliance with the ASHRAE 90.1 fan motorhorsepower requirement.The exhaust fan operates in parallel with the supplyfan. In this arrangement, the supply fan handles the fullstatic pressure requirements of the system. For normalbuilding pressure control, the exhaust fan operates todraw air from the return plenum and exhaust it out ofthe building.The exhaust fan configuration is available in two forms,modulating and non-modulating. Modulating is the mostcommon and recommended for the majority of applica-tions, while non-modulating should be used with in onlycertain circumstances.In the modulating exhaust system, the volume of airflowexhausted from the building is proportional to the enter-ing volume of outside air. Control is accomplished viaeither a discharge damper or a variable-frequencydrive(VFD). YORK recommends the use of a VFD to reduceenergy consumption, sound levels and improved reli-ability due to fewer moving parts.FIG. 1. TRADITIONAL OVERHEAD VAV AIRDELIVERY SYSTEM