Steam Humidifiers in Central Systems - Armstrong International, Inc.

Packaged Air Conditioner InstallationsHumidifiers frequently must be installed in packaged centralstation air conditioners. This can present some unusuallocation requirements due to the close quarters within thepackaged units.In the horizontal discharge draw-thru type packaged unitshown in Figure 35-1, the recommended location of thehumidifier is at the fan discharge. In some instances thismay not be possible. Note that with the alternate location,the humidifier manifold is installed to discharge upward intothe area of greatest air turbulence. This permits the air toachieve optimum mixing before reaching the fan blades. Ahigh-limit controller, set at 80%, should be located as shownwhen the humidifier is installed at the alternate location.Recommended humidifier locations for a vertical dischargedraw-thru type air conditioner (Figure 35-2) are identical to thehorizontal unit. If the alternate location must be used, a high-limitcontroller set at 80% is desirable. The humidifier manifold shoulddischarge upward, as with the horizontal discharge unit.Figure 35-1.Horizontal DischargeWith humidifier installed at recommended location, high-limit duct controller should beset at 90% RH maximum—alternate location at 80% RH maximum.Figure 35-2.Vertical DischargeDesigns, materials, weights and performance ratings are approximate and subject to change without notice. Visit armstronginternational.com for up-to-date information.Armstrong International - NAarmstronginternational.comArmstrong International - EUarmstronginternational.euArmstrong International - Chinaarmstronginternational.cnArmstrong International - Indiaarmstronginternational.inArmstrong International, Koreaarmintl.co.kr35

Steam Humidifiers in Central Systems, continued…In a low pressure blow-thru type, multi-zone, packaged airconditioner (Figure 36-1), the recommendations are much thesame. However, to avoid overloading the cold deck and to avoidimpingement of discharge, the manifold is installed to dischargeupward instead of directly into the fan discharge.As with the draw-thru units, a high-limit controller set at 90%should be installed. In a high pressure blow-thru type packagedunit (Figure 36-2), again the recommended location is as close tothe fan as possible, with the manifold discharging directly into thefan discharge. A high-limit controller set at 90% is desirable.In either high or low pressure systems, where the humidifieris installed at the alternate location, set the high-limit humiditycontroller at 80% RH.Figure 36-1.Low pressure systemFigure 36-2.High pressure systemDesigns, materials, weights and performance ratings are approximate and subject to change without notice. Visit armstronginternational.com for up-to-date information.36 Armstrong International - NAarmstronginternational.comArmstrong International - EUarmstronginternational.euArmstrong International - Chinaarmstronginternational.cnArmstrong International - Indiaarmstronginternational.inArmstrong International, Koreaarmintl.co.kr