EngA ENGINEERED AIR DJM2.4 Скачать руководство пользователя страница 24 | Manualshive

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EngA ENGINEERED AIR DJM2.4 Скачать руководство пользователя страница 24

DJM2.4 MANUAL

24

Oct 00 R2

NOTE:

After set up is complete remove jumpers.

XV.

SPECIAL SERVICE NOTES

On Board Fuse

The DJM2.4 is equipped with a 2-amp fuse. This fuse is located on the bottom of the main board.
If there is 24 VAC to terminals H and N and the DC voltage from terminals OS to GS is 0 VDC,
check the fuse.

(10.5 to 11.0 VDC is normal.)

Control is slow to respond to temperature demand.

Rapid Change in Load or Set Point

Two Speed and VAV Applications

The DJM2.4 likes to see stable discharge air temperatures. If the set point is changed rapidly

(lowered)

, the DJM2.4 may take up to 3 minutes to fully respond. The same conditions apply

to a load that is suddenly reduced.

(Vanes closing or low speed operation.)

Under these

conditions the discharge temperature may rise. If a problem is encountered with the high
limit tripping, consult the factory.

Checking Speed Sensor with the Fluke 80 Series Meter

Also refer to Section IX, Pre-Purge Status Light #1, for more information. The DJM2.4 has a Hall
Effect speed sensor to allow the control to closely monitor the combustion fan speed. There is a

fixed 10 VDC output from the
DJM2.4 terminals “GS” and “OS” to
the Hall Effect speed sensor if the
DJM2.4 is powered. The speed
sensor allows a return signal to be
measured on the “YS” and “GS”
terminals. If the fan is rotating
above 500 RPM, the signal can be
read as either an AC or DC voltage
and it will be about 5 volts. This is
because the fan is turning at a high
rate of speed and your meter is
averaging the reading. If the DJM2.4
has 24 volt power to it and the
combustion fan motor has been
disconnected from its power supply,

turning the combustion fan slowly by hand will result in a reading of 0 - then 10 VDC repeating as
the north and south poles of the magnet pass by the Hall Effect speed sensor. If the pre-purge
problem light is flashing the above steps should be checked.

If the DJM2.4 indicates a pre-purge problem the problem can be analysed more completely using
one of the Fluke 80 series meters. The DJM must see a near symmetrical square wave coming
from the Hall Effect speed sensor or it will reject the sensor signal. This wave is formed as the
magnet spins on the shaft with the north and south poles passing a Hall Effect speed sensor. This
speed sensor is a very small electronic chip located under the shrink-wrap at the end of the
copper tube. A simple method for estimating the wave form when the combustion fan is running

1/8" GAP

Collar

Blower

Shaft

Magnet

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Содержание ENGINEERED AIR DJM2.4

Страница 1: ...ND FACTORY CANADIAN EASTERN FACTORY 1401 HASTINGS CRES SE CALGARY ALBERTA T2G 4C8 Ph 403 287 4774 Fx 888 364 2727 32050 W 83 rd STREET DESOTO KANSAS 66018 Ph 913 583 3181 Fx 913 583 1406 1175 TWINNEY DRIVE NEWMARKET ONTARIO L3Y 5V7 Ph 905 898 1114 Fx 905 898 7244 SALES OFFICES ACROSS CANADA AND USA Retain instructions with unit and maintain in a legible condition Please give model number and seria...

Страница 2: ...from the unit There are two copies provided with the unit One is in an envelope for copying then return it to the unit or store in a safe place The other is attached to the control panel door and should never be removed If a copy of the function for a particular unit is needed contact Engineered Air with the unit serial number and DJM2 model number ex model DJM 2 4 Warning m c This unit is connect...

Страница 3: ...DJM2 4 MANUAL 3 Oct 00 R2 ...

Страница 4: ...E OVERRIDE 8 VIII STATUS LIGHTS 8 IX BASIC BURNER OPERATION 10 X TEMPERATURE CONTROL GENERAL OVERVIEW 11 XI BMS CONTROL 13 XII BMS CALIBRATION AND SET UP 13 XIII DISCHARGE SENSOR READOUTS CALIBRATION ETC 14 XIV BURNER SET UP 16 XV SPECIAL SERVICE NOTES 24 XVI SET UP WHEN INSTALLING A DJM2 4 IN FIELD 33 XVIII MISCELLANEOUS NOTES 34 XIX MAXITROL GAS VALVE DRAWINGS 37 ...

Страница 5: ... BMS The DJM2 has no built in low limit therefore it can be applied as stairwell pressurisation in case of fire The DJM2 is designed to replace the original DJM and has additional features to assist in troubleshooting II SERVICE To ensure warranty coverage and safe operation this equipment should only be serviced by qualified HVAC Technicians Gas Fitter and other properly trained trades people Bef...

Страница 6: ...t is not recommended but if a second control is connected to the DJM2 4 it will respond to the control with the greatest signal If direct reset control is required the DJM3 controller should be used Basic Features The basic features of the DJM2 4 include the following 1 Proportional and Integral PI temperature control 2 Can be used with the Johnson TE 6000 sensor and internal DJM2 set point pot It...

Страница 7: ...ture sensors flame rod etc This is to avoid voltage crosstalk stray induced high voltage signals that can adversely affect electronic controls V SYSTEM TIMINGS Pre purge 50 seconds combustion blower must run 50 seconds before flame can be lit on initial heat call if no combustion fan is in operation immediately before heat call Maintained Purge 4 minutes combustion blower runs after flame is turne...

Страница 8: ...fferent applications slightly different settings may be required Tests have indicated the best settings for various applications are For use with Maxitrol TS114 or Johnson TE 6000 960 sensors this pot should be left in the centre position 9 o clock or less position For use with a building management control system the pot should be set in the full CCW proportional position This includes METASYS an...

Страница 9: ...e AC volts present on terminals YS to GS When the combustion blower is running there should be 4 to 6 VAC present If the AC voltage is not present check the tachometer sensor to magnet gap It should be 1 16 to 1 8 inch If the gap is okay replace the speed sensor Further information found in section Checking Speed Sensor located on page 24 If the voltage is constantly 10 VDC and the sensor is locat...

Страница 10: ...ower is started 3 After the combustion blower is started the DJM waits until the blower reaches the correct pre purge speed Approximately 3450 RPM 4 When the correct speed is obtained the pre purge time delay is started While the combustion fan is operating in the pre purge mode the heat exchanger is purged of any unwanted gases that may be present 5 After the pre purge cycle is complete the combu...

Страница 11: ...s while the DJM2 4 is operating in its maintain purge mode the control logic goes to step 6 and the burner will re light 12 If there is no heat call within the 4 minute maintain purge mode the combustion blower is shut off If another call for heat is initiated at this time the control logic returns to step 1 Service Mode When DJM2 4 terminals SV and SR are jumpered the DJM2 4 is placed into servic...

Страница 12: ... etc The C TRAC pots are set as per the normal factory recommended settings To set the DJM2 4 controlled by a C TRAC See Section XVIII DJM2 Slaving From C TRAC for more information The C TRAC pots are to be set as per the following assuming it is sitting horizontal the label DJM2 4 is horizontal then CONT Pot 3 would normally be set at about the 9 o clock position or midway on its stroke If you wi...

Страница 13: ...If desired the wiring may be changed such that the BMS or control voltage is wired to terminals and These terminals are optically isolated and will eliminate the requirements for a separate ungrounded isolating transformer The control providing the signal to the and terminals needs to be a 0 10 VDC signal that has capability of a 20 ma or stronger drive For new installations we recommend using ter...

Страница 14: ... have an input impedance of 500 ohms on the and terminals At 10 VDC input the current would be 20 mA If the host BMS system cannot source 20 mA the input impedance can be increased to 1500 ohms by removing cutting resistor R19 680 ohms This resistor is located next to terminals and To gain access to R19 to cut it the DJM2 4 must be turned over BMS Calibration Refer to instructions in above section...

Страница 15: ...set point to match the measured discharge temperature Adjust pot 1 until the meter reading is 1 8 volts DC Note information below A second calibration method for the TE6000 without a meter is Ensure there is no signal such as voltage on that would call for a higher discharge than the temperature at the set point Next measure the temperature immediately next to the discharge air sensor Adjust the s...

Страница 16: ...rner plate and High Turndown rectangular Burners Cutting a jumper wire located next to terminal PV1 makes the selection For high turndown burner operation the jumper wire must be cut There are two pots located close to terminal SP which affect the burner set up These pots are to be adjusted only by a qualified service technician using proper combustion analysis equipment Pot 7 second pot from the ...

Страница 17: ...f the air and fuel may have a great affect on the set up you select If both the combustion air and the fuel are at a constant temperature throughout the heating season once combustion is set it should remain similar through the season However this usually only occurs on indoor units Setting up an outdoor unit is not the same as setting up a unit or a boiler inside a building When a unit is located...

Страница 18: ...sure is set up at the appliance regulator ES345D L This valve has a built in high fire regulator Used on DJ140 models The above valves differ from each other in size configuration BTU capacity physical layout and low fire set up Check the unit you are working on to verify what type of modulating gas valve you have to ensure the correct combustion set up method is used Top Loading Ensure that there...

Страница 19: ...in from less than 1 5 VDC until 2 25 VDC is reached 7 Check the O2 reading again at this point If the O2 has increased adjust the spring activated low fire adjustment on top of the valve until the O2 reading is same as the low fire reading at 0 VDC you are correcting for valve hysteresis with this adjustment 8 CURVE MATCHING PROCEDURE Switch to high fire setting approximately 3450 RPM or 57 5 Hz f...

Страница 20: ...ng the DJM2 Service pot 4 SER fully CCW Turn the ES345 low fire adjustment screw found under the valve cover near the wire terminals fully CCW Adjust DJM2 pot 8 MINSP until the combustion fan is turning 1250 RPM 10 RPM 20 8 Hz for 10 1 turndown 1195 RPM 5 RPM for 15 1 turndown 19 91 Hz Voltage to the ES valve should be 0 volts DC The low fire bypass adjustment on this valve is under the top cover ...

Страница 21: ... These valves do not have high fire regulators High fire pressure is set up at the appliance regulator This series of valve has been replaced with the M520 620 series ES345D L This valve has a built in high fire regulator High Fire Set Up 1 Place a jumper across the DJM2 4 terminals SV and SR to force the control into a manual firing mode 2 Set manual firing pot 4 labelled SER located near the mid...

Страница 22: ...d burners set pilot as per the following procedure Install a 10 000 ohm resistor in series with the flame rod circuit Connect a DC voltmeter across the resistor The reading will be in millivolts if your meter does not auto scale Connect a manometer to the pilot line Run the burner on main flame for a few minutes to have the burner plate warm Leave the pilot on but turn the main gas off You will ha...

Страница 23: ...up for propane fuels for either the high turndown or the standard burner are similar to the above The only modification suggested is it may be desirable to increase the oxygen settings by 1 to 1 5 above those for natural gas High turndown burners operating on propane fuel will generally exhibit the following High Fire 3 5 O2 will appear yellow from behind the burner However if you could view it fr...

Страница 24: ...ls GS and OS to the Hall Effect speed sensor if the DJM2 4 is powered The speed sensor allows a return signal to be measured on the YS and GS terminals If the fan is rotating above 500 RPM the signal can be read as either an AC or DC voltage and it will be about 5 volts This is because the fan is turning at a high rate of speed and your meter is averaging the reading If the DJM2 4 has 24 volt powe...

Страница 25: ...refer to LED 1 for more information If the test is done only for voltage and it proves to be correct there could still be a problem as the DJM 42 has a refined sensing circuit This circuit is looking for the magnet to be split fairly evenly The duty cycle test gives a reasonable view of the magnets split between north and south poles Speed Sensor Values With the speed sensor disconnected from the ...

Страница 26: ...next item Cold Discharge Temperature in Cold Weather At the time of installation and air balancing the air balancer in warmer weather often adjusts the unit s airflow If the unit is designed for Make up Air outside air being drawn into the building and heated as it passes through the unit then the quantity of air being delivered into the space will vary considerably as the outside air temperature ...

Страница 27: ...any factors including duct layout this location may not represent an average duct temperature Most discharge temperature sensors can be relocated into the duct work to correct problems of temperature stratification etc Last but by no means least is the application of a BMS sensor in the discharge by a control contractor Engineered Air suggests that both our sensor and the BMS sensor should be loca...

Страница 28: ...ools and the fan shuts off The DJM during this time has modulated to low fire There is not enough heat produced to remake the auto fan switch the DJM may continue to modulate at low fire depending on temperature conditions at the sensors Suggested resolution When C TRAC terminal K is powered at night the coil of a relay is powered The contacts of the relay are located between the DJM main gas feed...

Страница 29: ...the pilot tube 9 Usually changing the pilot assembly will not have much of an affect on the pilot signal if both assemblies are in good condition and installed correctly 10 Ensure the pilot assembly gasket is tightly installed to stop air leakage into the pilot area 11 Standard round burner only If the burner plate is not centered in the hole it may allow too much of a gap over the top of the burn...

Страница 30: ... high turndown burner On the standard burner it is possible to get small amount of rumble whenever a burner is lit after being cold for an extended period of time After the first light it settles down This is because the warm burner has a greater back pressure than the cold one thus a lower air velocity occurs when the burner plate is warm One of the more common causes on the regular burners round...

Страница 31: ... Not Respond to Signal to Open Items that may contribute to this are Ice in valve in bottom or above diaphragm Burnt out coil Sticky substance or debris in valve Modulating Valve Sticks When Returning to Low Fire If the modulating valve sticks partly open as the combustion fan slows down the combustion process will be very poor The products of combustion may smell badly or in rare instances even f...

Страница 32: ...ure failure due to thermal stress or freezing Another source of excess condensation is when a unit designed with capacity to heat 100 outside air is operating with very little outside air therefore operating at a low fire or cycling This allows the cool flue gases from low fire to cool and condense in the chimney Burner Pulsing Backfiring An improper air fuel mixture usually causes this condition ...

Страница 33: ...ntly turn off the manual valve on the pilot line Check to see if the fire has gone out If it has then the pilot solenoid is leaking and should be changed If there was no difference gently turn off the firing valve for the main manifold If this stops the fire this would prove the main solenoid blocking valve was leaking Replacement of Combustion Fan Motors Motors being used for combustion fan appli...

Страница 34: ...n acceptable temperature control band 4 NOTE If the DJM2 is controlled by a C TRAC2 1 or Metasys then resistor R19 should be cut before installation If the DJM2 4 is being controlled by a BMS signal that cannot put out enough VA to drive the DJM2 4 resistor R19 should be cut If the DJM2 is controlled by a C TRAC Megatrac METASYS or other BMS device that is wired to terminals and then Set combustio...

Страница 35: ...ct as described in the DJM2 manual section X Secondly if the above does not resolve the problem adjust the C TRAC COOLING DEADBAND Pot 3 to number value eleven Also access the C TRAC Pot eleven on the back of the C TRAC and set it to number 2 Thirdly if the above steps do not resolve the issue use an open sensor contact the factory for details Fourth if after doing the above and reasonable control...

Страница 36: ...ater usage and water quality There are water level controls sensing minimum and maximum water levels in the water heater A buildup of moisture and or dirt on some portions of the sensor ceramics may allow the heat to operate without proper water levels This could result in damage to the heat exchanger SH tank When servicing these water level sensors should be confirmed as operating correctly at le...

Страница 37: ...VER W LOCK RING VENT HOLE MUST BE PLUGGED IF VALVE IS TOP LOADED LOCATION BOTTOM SIDE FOR SECOND LOW FIRE ADJUSTMENT BYPASS WHITE PLASTIC DISK COVERING PLUNGER BLACK SIDE UP SPRING ON TOP OF PLUNGER POWER DRAWS PLUNGER UP REVERSE ACTING POWERS CLOSED MR410 MR510 AND MR610 N O VALVE DJ 20 DJ 40 WITH A1010 AMPLIFIER DJ 60 WITH DJT MODULE PACKS XE AND RT WITH MAXITROL A1010 AMPLIFIER SET HIGH FIRE MA...

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