Carrier WeatherMaster 48HC04 Service And Maintenance Instructions

Also see for WeatherMaster 48HC04 Series: Installation instructions

22Air is introduced to the duct smoke detector sensor’s sensingchamber through a sampling tube that extends into the HVAC ductand is directed back into the ventilation system through a (shorter)exhaust tube.The difference in air pressure between the two tubes pulls the sam-pled air through the sensing chamber. When a sufficient amount ofsmoke is detected in the sensing chamber, the sensor signals analarm state and the controller automatically takes the appropriateaction to shut down fans and blowers, change over air handlingsystems, notify the fire alarm control panel, etc.The sensor uses a process called differential sensing to preventgradual environmental changes from triggering false alarms. Arapid change in environmental conditions, such as smoke from afire, causes the sensor to signal an alarm state, but dust and debrisaccumulated over time does not.The difference in air pressure between the two tubes pulls the sam-pled air through the sensing chamber. When a sufficient amount ofsmoke is detected in the sensing chamber, the sensor signals analarm state and the controller automatically takes the appropriateaction to shut down fans and blowers, change over air handlingsystems, notify the fire alarm control panel, etc.For installations using two sensors, the duct smoke detectordoes not differentiate which sensor signals an alarm or troublecondition.Fig. 36 — Smoke Detector SensorSmoke Detector LocationsSUPPLY AIRThe supply air smoke detector sensor is located to the left of theunit’s indoor (supply) fan (see Fig. 37). Access is through the fanaccess panel. There is no sampling tube used at this location. Thesampling tube inlet extends through the side plate of the fan hous-ing (into a high pressure area). The controller is located on abracket to the right of the return filter, accessed through the lift-offfilter panel.Fig. 37 — Typical Supply Air Smoke Detector SensorLocationRETURN AIR SMOKE DETECTOR SENSOR WITHOUTECONOMIZERThe sampling tube is located across the return air opening on theunit basepan (see Fig. 38). The holes in the sampling tube facedownward, into the return air stream. The sampling tube is con-nected through tubing to the return air sensor that is mounted on abracket high on the partition between return filter and controllerlocation. (This sensor is shipped in a flat-mounting location. In-stallation requires that this sensor be relocated to its operating lo-cation and the tubing to the sampling tube be connected. See in-stallation steps in “Completing Installation of Return Air SmokeDetector” section.)Fig. 38 — Typical Return Air Smoke DetectorLocationRETURN AIR SMOKE DETECTOR SENSOR WITHECONOMIZERThe sampling tube is inserted through the side plates of the econo-mizer housing, placing it across the return air opening on the unitbasepan (see Fig. 39). The holes in the sampling tube face down-ward, into the return air stream. The sampling tube is connectedusing tubing to the return air sensor mounted on a bracket high onthe partition between return filter and controller location. The sen-sor is shipped in a flat-mounting location. Installation requires thesensor be relocated to its operating location and the tubing to thesampling tube be connected. See installation steps in “CompletingInstallation of Return Air Smoke Detector” section.SEE DETAIL ADETAIL APLUGSAMPLING TUBE(ORDERED SEPARATELY)COUPLINGMAGNETICTEST/RESETSWITCHALARMTROUBLEPOWERDIRTYSENSORCOVERCOVER GASKET(ORDERING OPTION)SENSOR HOUSINGAND ELECTRONICSEXHAUST GASKETEXHAUST TUBE DUCT SMOKE SENSORINTAKEGASKETTSD-CO2(ORDERING OPTION)SUPPLY AIRSMOKE DETECTOR*RA detector must be moved from shippingposition to operating position by installer.RETURN AIR DETECTORSAMPLING TUBERETURN AIRDETECTOR MODULE(Shipping positionshown)*CONTROLLERMODULE