Carrier 16JT Series Start Up & Operation Manual

Carrier 16JT Series Start Up & Operation Manual Manual pdf 28 page image

Start-Up After Limited Shutdown1. Place the capacity control, Cycle-Guard,™ and Local-Remote settings in the position indicated in Table 7.Table 7 — Start-Up Setting PositionsSETTINGS POSITIONCapacity Control AUTO.Cycle-Guard Switch AUTO.Local-Remote Switch AS APPROPRIATE2. Depress the Start button.Machine should start in normal manner and the Run lightshould be on. The refrigerant pump will start about 5 min-utes after chiller starts; the solution typically heats up to nor-mal operating conditions within 20 to 30 minutes.If, however, machine does not lower leaving chilled watertemperature to design, noncondensables may be present. Inthis case, take an absorber loss reading (see Maintenance Pro-cedures, Absorber Loss Determination section, page 31).If absorber loss is 5° F (3° C) or less, the chilled watertemperature should drop to design within a short period asthe automatic purge evacuates the machine. A completelyevacuated machine normally has an absorber loss of 2° F(1° C) or less.If absorber loss is greater than 5° F (3° C), follow the pro-cedure for Start-Up After Extended Shutdown.Start-Up After Extended Shutdown1. Start the machine in the normal manner by placing thecapacity control and Cycle-Guard settings in the posi-tions indicated in Table 7.2. Depress the Start button.When refrigerant pump starts and solution is warm (strongsolution approximately 100 to 130 F [38 to 55 C]), placecapacity control operation button in MANUAL positionand press the positioning button (ƒ) to shut the steamvalve.3. Determine machine absorber loss (see Maintenance Pro-cedures, Absorber Loss Determination section, page 31).If absorber loss is 5° F (3° C) or less, open capacity con-trol valve by placing capacity control button in AUTO.position and allow machine to operate. The purge willevacuate the machine to the normal absorber loss of 2° F(1° C) or less.If absorber loss is more than 5° F (3° C), evacuate ma-chine to remove noncondensables that can prevent nor-mal operation (see Maintenance Procedures, MachineEvacuation section, page 33). An alternative procedure isto limit steam pressure so that low-stage generator strongsolution temperature remains below 140 F (60 C) whilemachine purge removes the noncondensables.4. When absorber loss is reduced to 5° F (3° C) or less, placecapacity control switch in AUTO. position, return steampressure to normal and allow purge to establish the nor-mal 2° F (1° C) or less absorber loss rate.5. After evacuation, check the noncondensable accumula-tion rate to determine machine tightness (see Mainte-nance Procedures, Noncondensable Accumulation Ratesection, page 31).Start-Up After Below-Freezing Conditions —Refill all water circuits if previously drained. Then followprocedure for Start-Up After Extended Shutdown.Remove solution from the refrigerant circuit by followingthe procedure, Removing Lithium Bromide from Refriger-ant, page 35.Machine Shutdown — Normal Conditions1. Depress the Stop button momentarily. Machine goes throughautomatic dilution for about 15 minutes and shuts down.2. Close the main steam valve and stop system pumps. Leavemachine in this condition until the next start-up.Machine Shutdown — Below FreezingConditions1. Depress the Stop button momentarily. Wait until auto-matic dilution is complete (about 15 minutes) and all ma-chine pumps stop.2. Close the main steam valve and stop system pumps.3. Completely drain all tube bundles and flush all tubes withan antifreeze chemical such as glycol.4. a. The refrigerant circuit requires special treatment. Filla hose with water (to avoid letting air into the ma-chine), and connect it between the solution pump andrefrigerant pump service valves.b. Start the machine and open both service valves. Keepthe steam valve closed. If the machine has a refrig-erant pump with above atmospheric discharge pres-sure, it must be stopped for this procedure.c. Allow solution pump to run for 10 minutes. This willtransfer lithium bromide solution into the refrigerant,lowering the refrigerant freezing point. Close the serv-ice valves and remove the hose.d. Leave the machine running with all machine pumpsoperating for about one minute to be sure lithiumbromide has been mixed throughout the refrigerantcircuit.e. Depress the Stop button.28