Daikin RDT-135c Installation And Maintenance Manual

Contents

Daikin RDT-135c Installation And Maintenance Manual Manual pdf 119 page image

IM 738-2 117Maintenance: Refrigerant LeaksFigure 119. 44" and 49" SWSI airfoil wheel-to-funnelalignmentRefrigerant LeaksR-407C is a zeotropic blend of three HFC refrigerants (R-32,R-125, and R-134a). Zeotropic blends do not behave as onesubstance. Therefore, a change of phase does not occur at afixed temperature. R-407C has a “glide” of 8°F because itboils and evaporates over an 8°F change in temperature.If an R-407C unit leaks refrigerant, there is no way todetermine how much of each of the three componentrefrigerants leaked. However, experience in the field hasshown that R-407C systems can be “topped off” after a leakand will operate normally. There is no need, except in thecase of critically charged systems, to replace the entire chargeafter a leak.Add charge per instructions on page 42.Refrigerant ChargeThe unit nameplate references proper charge for each RPS/RDT refrigerant circuit in case a full charge must be added tothe unit. Verify these values using pages 39–41. Refer to pages39–41 for RFS/RCS units.Servicing Refrigerant Sensors or SwitchesThe Daikin Rooftop unit includes the following refrigerantsensors or switches.1 Low refrigerant pressure sensing, operating switch,automatic reseta Disables their associated compressors on a drop insuction pressure to approximately 35 psig.b Enables their associated compressors on a rise in suctionpressure to approximately 60 psig.2 SpeedTrol™ high refrigerant pressure sensor (not availableon sizes 15 to 30). See page 90 for more information.3 High refrigerant pressure, protective switch, manual reset,reset by breaking control power to the S1 control switch.a All R-22 high pressure switches disable their associatedcompressors on a rise in discharge pressure to 400 psig.b R-407C high pressure switches disable their associatedcompressors on a rise to the following dischargepressure:– Scroll compressor units (sizes 015 to 105C) =425 psig– Reciprocating compressor units (sizes 15 to 135C)= 400 psiga The switches have a differential of 100 psig.4 High pressure relief, protective valve on sizes 115 to 135Conly and located on the condenser headers.The low pressure and SpeedTrol sensors/ switches senserefrigerant pressure through shrader fittings that contain cores.The cores are stop valves that do not allow refrigerant to flowthrough the shrader unless the device is in place. Therefore thelow pressure and SpeedTrol sensors/switches can be replacedwithout reclaiming the refrigerant.The Shrader that serves the high pressure switch does notcontain a core in order to maximize the functionality of thesafety. Therefore it cannot be replaced unless therefrigerant has already been reclaimed.Winterizing Water CoilsCoil freeze-up can be caused by such things as air stratificationand failure of outdoor dampers and/or preheat coils. Routinedraining of water cooling coils for winter shutdown cannot bedepended upon as insurance against freeze-up. Severe coildamage may result. It is recommended that all coils be drainedas thoroughly as possible and then treated in the followingmanner.• Fill each coil independently with an antifreeze solutionusing a small circulating pump and again thoroughly drain.• Check freezing point of antifreeze before proceeding to nextcoil. Due to a small amount of water always remaining ineach coil, there will be a diluting effect. The small amount ofantifreeze solution remaining in the coil must always beconcentrated enough to prevent freeze-up.Note: Carefully read instructions for mixing antifreezesolution used. Some products have a higher freezingpoint in their natural state than when mixed with water.Table 31: 44" and 49" SWSI airfoil wheel-to-funnelRelationshipWheel-to-funnel relationship (in inches)Wheel diameter “A”44 16.2149 17.81WARNINGPotential severe loss of charge may occur if the high refrigerantpressure switch is replaced before reclaiming the refrigerant.Replace switch after reclaiming refrigerant.WheelunnelA