Carrier 39L Series Installation, Operation, And Start-up Instructions

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Carrier 39L Series Installation, Operation, And Start-up Instructions Manual pdf 109 page image

To verify or adjust submaster default values, perform thefollowing for each controlled device (control loop):1. Verify that controlled devices (cooling coil valve [CCV],heating coil valve [HCV]) are properly piped and wired.2. Using the local interface device, force each controlleddevice fully open and fully closed. Make sure the ac-tuators move smoothly. Sticky or sloppy actuators resultin poor control. They must be corrected, otherwise it maybe impossible to obtain stable control.3. Verify that all appropriate energy sources are available:hot water, chilled water, steam, etc.4. Verify that the system is in the Occupied mode and thesupply fan is running.5. Verify that the supply fan status indicates ON. If the fanstatus if OFF, the control algorithms hold the controlleddevices at the failsafe position.6. Verify that all forces have been removed.7. Table 24 indicates recommended starting values for SMG,MPG, and MIG for constant volume and variable air vol-ume units. Verify that these values have been entered.8. Verify/adjust the SMG. If the SMG is too large, the looptends to oscillate (hunt). If it is too small, the loop reactstoo slowly.Verify or adjust the SMG as follows:a. Using the local interface device, force the submasterreference of the control loop to a value above or be-low the actual sensor reading. Verify that the actua-tor responds correctly. If the actuator drives in thewrong direction, go to the submaster gain (SMG) forthe control loop and reverse the sign of the gain. Forexample: If the submaster loop gain is 5.0, change itto −5.0.Table 24 — Recommended Gain Starting ValvesGAIN VALUECV VAVHCV MPG 8.0 0.3*HCV MIG 0.3 1.5*HCV SMG† −7.5 −7.5CCV MPG 8.0 0.3*CCV MIG 0.3 1.0*CCV SMG** −7.5 −7.5MIXD MPG 8.0 0.5*MIXD MIG 0.3 1.5*MIXD SMG −7.5 −7.5IGV MPG — 0.5IGV SMG — 5.0EH MPG 8.0 8.0EH SMG 5.0 5.0PREHEAT/AO MPG 1.0 0.3PREHEAT/AO MIG 0.8 0.8PREHEAT/AO SMG† −3.0 −3.0PREHEAT/AO SCV†† 100% 100%*RFVC MPG — 0.5RFVC SMG — 10.0HUM MPG 2.0 2.0HUM SMG 7.5 7.5*Differs from default value; change the default value to obtain therecommended starting value shown.†Values shown are for normally-open valves. If normally-closed valvesare used, see Step 8.**Values shown are for normally-closed valves. If normally-open valvesare used, see Step 8.††Values shown are for normally-open valves. If normally-closed valvesare used, subtract initial value specified from 100% to obtain thecorrect value. Example:100% − (SCV N.O.) = (SCV N.C.)100% − 100% = 0%b. Observe the operation of the controlled device for afew minutes. If the device oscillates every few sec-onds around the forced value, then lower the SMGby small amounts until the output steadies. If the out-put to the device responds to a change in temperaturein small increments, then increase the SMG in smallamounts until the output steadies.NOTE: Do not be alarmed if the submaster sensor sta-bilizes at a value greater than or less than the forcedvalue. This is termed the submaster droop offset and isnormal.9. It is not necessary to adjust the submaster loop centervalue, as the master loop will adjust the submaster ref-erence as required to satisfy its set point. However, itmay be desirable to keep the submaster droop to a mini-mum. This is most often required for heating coil loops,(especially on steam coils where the control valve has atendency to be oversized).If the submaster droop is too large, adjust the SCV asfollows:If the submaster droop is positive (actual value greaterthan reference value), the SCV should be decreased forHCV and IGV loops and increased for CCV and MIXDloops. If the submaster droop is negative (actual valueless than reference value), the SCV should be increasedfor HCV and IGV loops and decreased for CCV andMIXD loops.10. Once the submaster loop is adjusted, remove all forcesand proceed with verification and adjustment of masterloop.11. To check the master loop, create an error in the masterloop. For example: Change the actual space temperatureto a value less than the heating set point or greater thanthe cooling set point.Observe system (loop) response for 10 to 20 minutes toverify stable control. After 10 minutes if the output con-tinues to swing full open to full closed, lower the MPGand observe again. Do this until the loop operation isstable. After 10 minutes, if the loop does not seem torespond (little change in submaster reference), increasethe MPG and observe again. Do this until stable opera-tion is achieved.12. Once you are satisfied with loop operation, remove allforces which may have been initiated during thisprocedure.13. Repeat steps 1-12 until all loops have been checked.VALVE TROUBLESHOOTINGGeneral — To facilitate troubleshooting the valve, it maybe necessary to disassemble the electronic actuator from thevalve body.All 1 ⁄ 2 -in. Through 1 1 ⁄ 4 -in. Electric Hot Water/Steam Valve Assemblies — A high-temperature link-age extension is supplied to help insulate the hydraulic ac-tuator from heat. See Fig. 80. Mount valves so that valvestem is at a 35° to 45° angle from vertical. See Fig. 81.109