Daikin FC Series Page 25 Installation And Maintenance Manual Download

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Troubleshooting

The RM7897A flame safeguard is equipped with an LED to aid in the diagnosis of burner operation and problems. Fault

identification is a series of fast- and slow-blinking LED lights. The fast blinks identify the tens portion of the fault code (two fast

blinks is 20), while the slow blinks identify the units portion of the fault code (two slow blinks is 2) . Two fast blinks followed by two

slow blinks would be fault code 2-2. This identifies a flame signal absent at the end of the pilot flame establishing period. (See

Table 7: Fault codes

for Blinking Fault Code List .) The LED code repeats as long as the fault exists . To clear the fault, press the

RESET button .

Troubleshooting

www .DaikinApplied .com 25

IM 684-6 • ROOFTOP SYSTEMS

Summary of Contents for FC Series

Page 1: ...Installation and Maintenance IM 684 6 Group Applied Air Systems Part Number IM 684 Date October 2018 Daikin Rooftop Systems Forced Draft Gas Fired Furnace FC A with RM7897A Flame Safeguard ...

Page 2: ...I Control Systems 13 Modulating Gas Burner without End Switch Cycling 14 Typical Sequence of Operation 3 1 gas burner with no MicroTech III Control System 15 Service 16 General 16 Pilot Air Gas Adjustments 16 Pressure Regulator 16 Pilot Orifice 16 Ignition Electrode Adjustments 16 Flame Rod Adjustment 17 Pilot Location Adjustment 17 Air Pickup Tube Adjustment 17 Gun Assemblies 17 Modulating Linkag...

Page 3: ... RISQUE D INCENDIE OU D EXPLOSION Le non respect des mises en garde pourrait entraîner des blessures graves la mort ou des pertes matérielles Prende soin de lire et de comprendre les instructions d installation de fonctionnement et d entretien contenues dans ce guide Une installation un réglage une modification une réparation ou un entretien inapproprié peut entraîner des blessures graves la mort ...

Page 4: ...caps Warranty Exclusion Warranty is void if the furnace is operated in the presence of chlorinated vapors if the airflow through the furnace is not in accordance with rating plate or if the wiring or controls have been modified or tampered with Ventilation Flue Pipe Requirements The Daikin rooftop unit is equipped with an outdoor air louver to supply adequate combustion air The unit also has a flu...

Page 5: ...ner section On Models 150 through 200 it is shipped in the same crate as the vestibule Remove and discard the shipping cover installed over the furnace tube outlets before installing the flue box 1 Remove the screws 2 in the casing of the unit that line up with the bottom lip holes of the flue box tube sheet 3 These screws will later be replaced at which time they will also attach the bottom of th...

Page 6: ... within the pressure range mentioned above Gas Piping The connection size at the burner is shown in Table 10 under columns 17 and 18 Gas piping must be sized to provide the minimum required pressure at the burner when the burner is operating at maximum input Consult your local utility on any questions on gas pressure available allowing piping pressure drops and local piping requirements Install al...

Page 7: ...ot run to the outside of this vestibule If local regulations require that this be done it is a part of the field gas piping hookup Remove any plastic protector plugs from regulator and valve vents Normally Open Vent Valve Vent valves such as required by IRI for over 1000 MBh input units must always be routed to the outdoors This is field piping Gas Piping Routing into Unit On The Roof Piping Model...

Page 8: ...off valve when required for IRI etc will require careful use of the available space The examples shown in Figure 5 indicate typical piping layouts Field Gas Piping Required The gas train components have all been factory installed and require only a connection to the supply gas line The manual shutoff valve is located within the burner vestibule If local codes require a manual shutoff valve that is...

Page 9: ...ines may cause a build up of condensate inside the heat exchanger resulting in leakage and damage to the rooftop unit and probably to the facility These two furnace sizes exceed the allowable shipping width and for this reason the burner is disconnected and removed for shipment A sheet metal vestibule weather enclosure is also disassembled for shipment At installation the burner must be re mounted...

Page 10: ...nd meet the equipment requirements 5 Determine that proper instruments will be available for the start up A proper start up requires the following voltmeter manometer or gauges with ranges for both manifold pressure and inlet gas pressure keyboard display module or a 20K ohm volt meter for flame safeguard signal strength measurement CO2 indicator carbon monoxide indicator and a stopwatch for timin...

Page 11: ...ure through the hole Modulating burners are to be at their high fire position for this measurement Table 10 Column 8 indicates typical readings and any appreciable deviations from these would indicate a burner air problem that should be found before attempting to fire the unit These problems could include linkage adjustments disturbed during shipment etc 2 With control switch at OFF connect the ma...

Page 12: ...Typical Electrical Schematic for MicroTech III Control System with RM7897A IM 684 6 ROOFTOP SYSTEMS 12 www DaikinApplied com Start Up and Operating Procedures ...

Page 13: ...ves GV4 and GV5 will be energized and the control system will be allowed to control the firing rate once the heating stage timer default 5 minutes has passed After the flame has lit and been proven and the heating stage time has passed the controller will modulate VM1 to the required firing rate via analog output EXPB AO_X7 In the event the flame fails to ignite or the flame safeguard fails to det...

Page 14: ...llers will determine the firing rate The modulating controls position an operator which will change both gas and airflow proportionally The modulating control will always go to the low fire position for light OFF Figure 10 Typical Electrical Schematic with no MicroTech III Control System IM 684 6 ROOFTOP SYSTEMS 14 www DaikinApplied com Start Up and Operating Procedures ...

Page 15: ...mplete the pilot flame will ignite and be detected by the Flame Safeguard FSG through the Flame Rod FD Terminal 10 Ignition Transformer IT will de energize when the pilot flame is detected Terminal 9 Main Gas Valve GV2 energizes and the main flame will ignite The Flame Safeguard FSG contains an LED at the lower left corner which will glow to indicate operation The firing rate of the burner is dete...

Page 16: ...stment kinked or damaged so it is not providing adequate air to the pilot 8 If the pilot flame signal voltage is within the range specified above use that peak midpoint setting as the pilot gas pressure setpoint 9 Determine that the pilot will hold in satisfactorily at BOTH high and low fire on modulating burners Test this by observing the flame signal as the burner repositions from low fire to hi...

Page 17: ... flame safeguard Once kinked the tube will probably have to be replaced Figure 13 Air Pickup Tube Gun Assemblies The Daikin gas burner has an easily removable gun assembly which includes the complete pilot burner assembly and the main flame burner head The position of this assembly within the burner blast tube determines the shape of the flame This is adjusted at the factory and normally does not ...

Page 18: ...p on the manifold to measure gas pressure at the orifice When the modulating operator is positioned to the minimum fire position and the burner is operating readjust C to obtain the specified minimum fire gas pressure on the orifice Typical 0 44 in W C natural gas Readjust D to obtain an even quiet flame and the specified CO2 and CO 10 Reposition modulating operator to high fire position and adjus...

Page 19: ...gs CO2 9 to 10 percent at maximum rate 9 to 10 percent at minimum rate CO 001 percent 10 PPM or less Cleaning Heat Exchangers Models 032 thru 200 see Figure 16 1 Remove the flue box front wrap 1 and the rear inspection cover 3 2 Remove and clean the turbulator 2 from each tube and clean the flue box 3 Clean each tube with a 2 1 2 round flue brush 4 Remove the bushings and if required clean the com...

Page 20: ...eat exchanger Remove the remains of the smoke bomb and uncover the flue box openings before attempting to operate the furnace Causes of Failures 1 Improper Application The furnace rating plate specifies a Minimum Airflow CFM The furnace must not be operated when airflow is below this minimum cfm If the furnace is being used on a variable air volume system the control system must be such that the f...

Page 21: ... and consequently the more condensate Do not think a furnace has a problem because it produces condensate anymore than you would think a cooling coil has a problem because it produces condensate However suitable steps must be taken to manage the flow of the condensate produced Most condensate will be produced in the secondary tubes where flue gas will sweep it into the flue box Condensate will als...

Page 22: ... shutting off on high limit at these settings it indicates that there is a problem with the furnace not getting enough air or it is being overfired Table 5 Limit Control Set Points BURNER MODEL LIMIT CONTROL SET POINT BURNER MODEL LIMIT CONTROL SET POINT 020 215 079 181 025 160 080 229 032 196 100 170 040 154 110 222 050 229 140 168 064 185 150 194 065 232 200 151 Replacing White Rogers Fan Limit ...

Page 23: ...l or flue passages in need of cleaning can cause changes in CO2 reading When a readjustment seems necessary do not make the adjustment without first trying to determine if the required change is not an indication that something else is in need of correction 3 Flame Safeguard Perform a flame failure check and pilot turndown test See control manufacturer s bulletin for further information 4 Motor Mo...

Page 24: ...must be proven at the end of that 10 second period or a shutdown will occur Run If Pilot flame is proven at the end of the 10 second ignition trial the main gas valve will be powered If a flameout occurs the module will recycle within 3 seconds and initiate a new prepurge period If pilot flame continues to be detected the module will be in Run until the power is interrupted to terminal 6 indicatin...

Page 25: ...blinks is 20 while the slow blinks identify the units portion of the fault code two slow blinks is 2 Two fast blinks followed by two slow blinks would be fault code 2 2 This identifies a flame signal absent at the end of the pilot flame establishing period See Table 7 Fault codes for Blinking Fault Code List The LED code repeats as long as the fault exists To clear the fault press the RESET button...

Page 26: ...age at terminal 4 and L2 If powered the problem is with the burner motor or its associated controls On Models 1100 2000 terminal 4 only controls a contactor and burner motor power comes from its own circuit breaker If terminal 4 is dead check for power to terminals 6 and L2 d IF VOLTAGE IS ZERO The power is being interrupted by the limit control the manual reset high or auto reset low gas pressure...

Page 27: ...ot Air and Gas Adjustment section 2 6 Pilot flame comes on but flame safeguard still locks out a The flame safeguard is not detecting pilot flame Check flame safeguard using Table 7 If this confirms flame safeguard is working and the pilot is coming on during the 10 second ignition trial period then the pilot is not producing an adequate flame signal Check pilot and its adjustments as listed above...

Page 28: ... flame signal when operating at both high fire and low fire e Check that the pilot ignition electrode porcelain bushing is blocking air passage into hole in pilot assembly Check the pilot burner for cracks that could allow air leakage into the pilot burner On modulating burners this leakage changes as the burner air damper changes air pressure and perhaps the pilot will produce a strong microamp s...

Page 29: ...from ignition Also determine that ignition electrode spark gap is within specifications 4 6 When the flame safeguard is powered it locks out and the ALARM LED comes ON a Check Table 7 The LED code may diagnose the problem b Purge card missing or bad terminals are energized that should not be at that stage or there is an internal system fault Replace purge card or RM7897A as indicated Troubleshooti...

Page 30: ...and or the flame detector g If the fault persists replace the relay module Code 2 2 Flame Signal Absent No flame time present at the end of the Pilot Flame Establishing Period lost during the Main Flame Establishing Period or during RUN a Measure the flame signal If one exists verify that it meets specifications b Make sure that the flame amplifier and flame detector are compatible c Inspect the m...

Page 31: ...k to RUN e If steps 1 through 4 are correct and the fault persists replace the relay module Code 3 2 Running Interlock On During Standby Lockout Interlock powered at improper point in sequence or On in Standby a Check wiring to make sure that the Lockout Interlocks are connected properly between terminals 6 and 7 Correct any errors b Reset and sequence the relay module c If the fault persists meas...

Page 32: ... module e If the fault persists replace the relay module Code 4 3 Flame Amplifier Problem Flame not sensed sensed when it should be ON or OFF a Check wiring correct any errors b Make sure the flame amplifier and flame detector are compatible c Remove the flame amplifier and inspect the connections Reseat the amplifier d Reset and sequence the relay module e If the code reappears replace the flame ...

Page 33: ...ing properly c Stat Switch held ON too long d Reset and sequence the relay module e Reset and sequence the relay module If the fault persists replace the relay module RM7838A1014 RM7838B1013 or RM7838C1004 only Code 6 1 Internal Faults Relay Module self test failure a Reset and sequence the relay module b If fault reappears remove power from the device reapply power then reset and sequence the rel...

Page 34: ...19643000 1 2000 MBH Furnace 036235700 1 Relay after 3 10 R20A 349934764 Burner Blast Tube 1 Relay after 3 10 R23A 349934764 1 200 400 MBH Furnace 037378802 1 Relay after 3 10 R20B 193454703 1 500 650 MBH Furnace 034101703 1 Relay after 3 10 R23B 193454703 1 790 1000 MBH Furnace 034101707 1 Fan Motor Contactor 1100 2000 mbh only M29 024700700 1 1100 1400 MBH Furnace 034101706 Relays MicroTech II Un...

Page 35: ... Gas heating section N A N A N A 344884B 00 GV2 3 Main gas valve Open to allow flow of gas to main burner Normally closed Gas heating section N A N A N A Varies with size HPR High pressure regulator Regulates pressure to main regulator N A In gas line before MPR As specified 10 13 w c 2491 3238 Pa N A Varies with size HP5 High gas pressure switch IRI option Shuts off burner if pressure goes above ...

Page 36: ...2000 61 1 40 58 3 00 2 8 0 563 3 86 3 13 0 97 0 42 7 5 3 9 0 35 0 87 4 58 5 30 5 60 0 80 3 20 1 25 1 25 1 25 080 1000 333 7340 100 1 50 58 2 60 2 5 0 563 3 35 2 71 0 84 0 29 7 5 3 9 0 35 0 87 4 64 6 00 6 56 0 85 3 05 1 25 1 25 1 25 100 1250 417 15000 61 1 60 58 2 60 2 9 0 750 3 67 2 97 0 92 0 23 9 0 4 2 0 12 1 00 4 90 6 88 7 81 0 93 3 12 1 38 1 25 1 25 110 1375 495 10100 100 2 05 58 3 32 2 8 0 703...

Page 37: ...s 10 Burner Motor Amps 11 Mid Rate Scale 50 Gas Manifold Pressure In W C 12 Gas Line Pressure In W C 13 Flame Signal DC Volts 14 Ambient Temperature Deg F 15 Flue Gas Temperature Deg F 16 Flue Gas C02 percent 17 Flue Gas CO PPM 18 Air Pressure in Box In W C 19 Min Rate Scale 5 Gas Manifold Pressure In W C 20 Gas Line Pressure In W C 21 Flame Signal DC Volts 22 Ambient Temperature Deg F 23 Flue Gas...

Page 38: ...ant to its standard terms and conditions of sale including Limited Product Warranty Consult your local Daikin Applied representative for warranty details To find your local Daikin Applied representative go to www DaikinApplied com Aftermarket Services To find your local parts office visit www DaikinApplied com or call 800 37PARTS 800 377 2787 To find your local service office visit www DaikinAppli...

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Daikin FC Series, Installation And Maintenance Manual

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