Daikin MPS015 F Installation And Maintenance Manual

Contents

• Lead/Lag Arrangement w/ MHGRH (when applicable)— Alternate staging with circuit #1 as lead will be thestandard default arrangement.— During cooling mode, circuit #1 will lead and load upbefore starting circuit #2.— During reheat mode, circuit #2 will lead and load upbefore starting circuit #1.— For reheat operation, compressor(s) in circuit #2 mustbe active. If the unit is operating in the cooling modewhen a call for dehumidification/reheat arises,circuit#2 will become the lead and the controller will bringon an additional stage of coolingfor dehumidification.If any compressors in circuit #1 are operating at thismoment they will be switched over to compressorsin circuit #2. Dehumidification operation is disabled ifcircuit #2 is disabled for any reason.• In the reheat mode, the minimum position for the reheatvalves is 10% (1.0 Vdc). The controller will modulate thereheat valves from this starting position.• Reheat valve(s) must be at 0% (0 Vdc) position beforestarting the first compressor in the reheat circuit toprevent pressure spikes.• Upon termination of dehumidification (reheat), themaximum ramp down or decay rate of the reheat controlvalves shall be 1% per sec (or 0.1V per sec).• Upon termination of dehumidification (reheat), stagingof compressor(s) is delayed for 1 minute after reheatcapacity = 0% (0 Vdc).• Every 24 hours, the reheat control valves will be driven totheir maximum position (10Vdc) and then returned to theirnormal operating position (0Vdc). If unit is operating incooling or dehumidification (reheat) at the prescribed timeit will be deferred to the next time.• Dehumidification status can now be found under the MTIIImain system menu. Reheat capacity (valve position)can also be found under the main system menu, displaybased on percentage (0-100%).Figure 34: Modulating Hot Gas Reheat SchematicoPTIonal modUlaTInG hoT Gas reheaTwww.DaikinApplied.com 41 IM 1058-8 • MAVERICK II ROOFTOP SYSTEMS