Carrier WeatherMaker 48A020 Installation Instructions Manual

Also see for WeatherMaker 48A020: Installation and operating instructions Installation instructions

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Carrier WeatherMaker 48A020 Installation Instructions Manual Manual pdf 23 page image

23Step 7 — Install Gas Piping — Unit is equipped foruse with natural gas. Installation must conform with localbuilding codes or, in the absence of local codes, with the Na-tional Fuel Gas Code, ANSI Z223.1.Install manual gas shutoff valve with a 1/8-in. NPT pressure tapfor test gage connection at unit. Field gas piping must includesediment trap and union. See Fig. 22. A 1/8-in. NPT is alsolocated on the gas manifold adjacent to the gas valve.Size gas-supply piping for 0.5-in. wg maximum pressure drop.Do not use supply pipe smaller than unit gas connection.OPTIONAL STAGED GAS UNITS — See Table 7 for stagedgas information. Staging pattern is selected during controlsstart-up.For complete information and service instructions for stagedgas control units, see Controls, Start-Up, Operation, Serviceand Troubleshooting literature.Table 7 — 48A Series Staged Gas ControlStep 8 — Install Supply-Air Thermistors(Staged and Modulating Gas Units Only) —Supply-air thermistors are a field-installed, factory-providedcomponent. Three supply-air thermistors are shipped withstaged and modulating gas units inside the unit control box.Thermistor wires must be connected to the SGC (staged gascontroller) in the unit control box. See Table 8. The supply-airthermistors should be located in the supply duct with the fol-lowing criteria:• downstream of the heat exchanger cells• equally spaced as far as possible from the heatexchanger cells• a duct location where none of the supply air thermistorsare within sight of the heat exchanger cells• a duct location with good mixed supply air portion of theunit.Table 8 — SGC Thermistor DesignationsSGC — Staged Gas ControllerWARNINGDo not pressure test gas supply while connected to unit.Always disconnect union before servicing. Personal injuryor damage to unit may occur.IMPORTANT: Natural gas pressure at unit gas connectionmust not be less than 5 in. wg or greater than 13.5 in. wg.Fig. 21 — Condensate Drain Trap Piping Details(Typical Roof Curb or Slab Mount Shown)a48-3714NUMBER OFSTAGESMODEL NUMBER POSITION HEAT SIZE5 6,7,85 STAGESS020025027030035040050LowT035040050High7 STAGES T020025027030High9 STAGES T 060 High11 STAGES S 060 LowFig. 22 — Field Gas Pipinga48-2524THERMISTOR PINCONNECTIONPOINTFUNCTION AND LOCATION PART NO.ThermistorsSAT1 J8 – 1,2 (SGC) Supply-Air Thermistor (SAT) — Inserted into supply section underneath thegas heat section (factory-provided, field-installed)HH79NZ034SAT2 J8 – 3,4 (SGC) Supply-Air Thermistor (SAT) — Inserted into supply section underneath thegas heat section (factory-provided, field-installed)SAT3 J8 – 5,6 (SGC) Supply-Air Thermistor (SAT) — Inserted into supply section underneath thegas heat section (factory-provided, field-installed)LIMTTEMP J8 – 15,16(SGC)Limit Switch Thermistor (LIMTTEMP) — Inserted next to the lower limit switch(factory-installed)