HEATEC TEC-NOTE. TROUBLESHOOTING Heatec thermal fluid heaters. Scope CONTENTS. Variations. Publication SAFETY

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1 HEATEC TEC-NOTE TROUBLESHOOTING Heatec thermal fluid heaters CONTENTS Safety...1 Scope...1 Variations...1 Intended users...2 Troubleshooting basics...2 Low media level switch...6 Circulating pump motor auxiliary contacts...6 Low fuel gas pressure switch...7 High fuel gas pressure switch...7 High media temperature limit controller...7 Temperature limits of exhaust gases...8 Combustion air motor auxiliary contacts...9 Low combustion air pressure switch...9 Fuel oil pump auxiliary contacts...9 Low fuel oil pressure switch...9 Pilot gas pressure regulator...10 SAFETY Before troubleshooting your heater please read the safety information shown in Heatec Tec-Note It is the first Tec-Note in this manual. Review each procedure entirely before performing any of its instructions. Do not deviate from these instructions unless you are sure it is safe to do so. If you do not perform step-by-step instructions in the order given you could create unforeseen safety hazards. Scope This Tec-Note provides instructions for troubleshooting key components on a variety of Heatec thermal fluid heaters (Fig. 1, 2, 3). However, the instructions are limited to our heaters that employ helical coils. Variations Instructions in this document are specific for heaters that have the burner management controls shown in Figure 6. These are currently used on most Heatec thermal fluid heaters. The photos in this document show a variety of heaters and components. Your heater may differ from those shown. But most heaters have devices that perform the same basic functions despite differences. So you should be able to adapt the information presented herein to your heater. Figure 1. Two Heatec horizontal helical coil heaters. One has an output of 60 million Btu/hour. The other has an output of 0.7 million Btu/hour. Figure 2 (above). Heatec vertical helical coil heater. The burner is on its bottom and is up-fired. Figure 3 (right). Heatec 3-pass vertical heater. Its burner is on its top and is down-fired.

2 INTENDED USERS Instructions in this document are intended for use by plant personnel who understand electrical shock hazards and how to avoid them. Such persons should also know about the usual burn hazards present when working with thermal fluids heated to temperatures in excess of 300 degrees F. Some procedures require making electrical tests and settings inside the heater electrical control panel while it is open and electrical power is turned on. This should be done only by persons authorized by their employer to work inside panels while significant electrical hazards are present. Employers and/or owners should have prescribed safety procedures for such work. TROUBLESHOOTING BASICS Although troubleshooting is something you normally do only after your heater has a problem, it is useful to gain knowledge of how things work beforehand. We recommend that you get familiar with the information in this document without waiting for a problem to develop. Most of the devices covered in this document are incorporated in the heater s 3 P interlock circuit. Each of these devices is intended to detect a specific abnormal operating condition. If any of these devices encounters the abnormal condition for which it is intended, it will shut down the burner and activate the heater s warning system. On some heaters the warning system uses a red light on top of the panel. It flashes when an abnormal condition triggers a shutdown. Other heaters use an audible alarm. You must find and fix the problem before you can restart the heater. If a shutdown happens you will see a LOCKOUT message on the burner display. The first line of the message indicates the operating condition when the lockout happened. The second line indicates what abnormal condition triggered the lockout. The lockout message may identify one of the limit devices in the 3 P interlock circuit as the cause of the shutdown. A clogged strainer is often the source of one or more abnormal conditions that will open an interlock device in the 3 P circuit. It can cause high media temperature. It can cause high stack temperature. And it can cause inadequate pressure differential across the coil. Improper settings of a pressure differential switch is also a common cause of 3 P interlock shutdowns. Lockout messages on the burner display may indicate that a shutdown was caused by abnormal conditions not related to the 3 P circuit. A message that says M-8 LIMIT OPEN is usually caused by a problem with the burner modulation motor. A message that says LOCKOUT STANDBY FALSE FLAME usually indicates a faulty flame scanner (when there is really not a flame in the burner). A message that says LOCKOUT PTFI FLAME FAIL is usually caused by a problem with the flame scanner, or with fuel, or with ignition. A message that says LOCKOUT AUTO FLAME FAIL is usually caused by a problem with fuel or combustion air. There is also the possibility that an interlock device itself has malfunctioned and has caused a shutdown. Or there may be yet another cause. In reality, troubleshooting is a process of elimination that starts with the lockout message. For example, assume the burner shuts down and the display says LOCKOUT LO MEDIA LEVEL. Obviously, the first thing to do is to check the level of thermal fluid in the expansion tank. If it is actually too low, fixing the problem may be as simple as adding thermal fluid to the system and making sure there is no leak in the piping system. If it is not too low, the next thing to check is the media level switch located in the expansion tank. If the switch is okay the problem is almost certainly to be a faulty wiring connection. The information in this document should enable you to determine whether various interlock circuit devices are working properly. Page 2

3 A B C Q P O N M L K J I H G F E D A. Expansion tank B. Expansion tank filler C. Heater end cover plate D. Outlet from helical coil E. Valve No. 2 (purge) F. Thermal fluid return inlet G. Valve No. 3 (expansion) H. Inlet pressure gauge I. Pressure differential switch J. Outlet pressure gauge K. Valve No. 1 (strainer) L. Inlet pressure gauge port M. Strainer N. Valve No. 4 (coil inlet) O. Burner fan motor P. Circulating pump Q. Circulating pump motor Figure 4. Location of components on a basic heater. Page 3

4 RESET MDFY Part No Part No BLV512 BURNER MODULATION CONTROLLER MEDIA HIGH-TEMPERATURE CONTROLLER MODE NEXT BACK BURNER DISPLAY GAS OIL OFF ON OFF ON DANGER FUEL SELECTOR CIRCULATING PUMP BURNER PART NO SHOCK HAZARD. Hazardous voltage is present inside this panel. Contact with it will cause death or serious injury. Disconnect and lock out electrical power to this panel before opening the panel door. PELIGRO RIESGO DE ELECTROCUCION. Hay niveles peligrosos de voltaje dentro de este tablero. El contacto causará la muerte o lesiones graves. Desconectar y bloquear la alimentación eléctrica suministrada a este tablero antes de abrir su puerta. ABNORMAL SHUTDOWNS If the heater encounters an abnormal operating condition it will shutdown and the red light on top of the Improper settings of the two pressure differential inadequate pressure differential across the coil. panel will flash. You must find and fix the problem switches are also a common cause of 3-P interlock before you can restart the heater. shutdowns. If a shutdown happens you will see a LOCKOUT message on the burner display. that a shutdown was caused by abnormal conditions Lockout messages on the burner display may indicate not related to the 3-P circuit. A message that says M-8 The first line of the message indicates the operating LIMIT OPEN is usually caused by a problem with the condition when the lockout happened. The second line burner modulation motor. indicates what abnormal condition triggered the lockout. A message that says LOCKOUT STANDBY FALSE FLAME usually indicates a faulty flame scanner (when The lockout message may identify one of the limit there is really not a flame in the burner). devices in the 3-P interlock circuit as the cause of the shutdown. A message that says LOCKOUT PTFI FLAME FAIL is usually caused by a problem with the flame scanner, A clogged strainer is often the source of one or more or with fuel, or with ignition. abnormal conditions that will open an interlock device in the 3 P circuit. It can cause high media temperature. A message that says LOCKOUT AUTO FLAME FAIL is It can cause high stack temperature. And it can cause usually caused by a problem with fuel or combustion air. PART NO To ensure that the flame scanner is working properly, manually restart the heater twice daily. If the scanner is not working properly it will prevent a restart and should be replaced. Never disconnect the scanner temporarily to restart the heater. That would would prevent it from shutting off fuel in case of a flame failure. This could cause an explosion and fire, causing injury or death. Para asegurar que el explorador de llamas funciona correctamente, rearrancar el calentador manualmente dos veces por día. Si el explorador no funciona correctamente, se impedirá el rearranque de la unidad. En tal caso, sustituirlo. Nunca desconectar el explorador de modo temporal para poder rearrancar el calentador porque entonces no se cortaría el suministro de combustible en caso de apagarse la llama. Esto podría ocasionar una explosión o incendio y causar lesiones personales o la muerte. Figure 5. Typical control panel. BLV512 BURNER MODULATION CONTROLLER MEDIA HIGH-TEMPERATURE CONTROLLER RESET NEXT MODE BACK MDFY BURNER DISPLAY GAS OIL OFF ON OFF ON 0.88 DIA 0.13 KEY 0.88 DIA 0.13 KEY 0.88 DIA 0.13 KEY FUEL SELECTOR CIRCULATING PUMP BURNER PART NO Figure 6. Operating controls currently used on many Heatec thermal fluid heaters. Page 4

5 L A K B C D E F J G I H A. Breaker auxiliary contacts for fuel oil pump motor B. Breaker auxiliary contacts for combustion air blower motor C. Breaker disconnect for combustion air blower motor D. Breaker disconnect for fuel oil pump motor E. Contactor for combustion air blower motor F. Auxiliary contacts for combustion air blower motor G. H. I. J. Auxiliary contacts for fuel oil pump motor Contactor for fuel oil pump motor Contactor for media circulating pump motor Auxiliary contacts for media circulating pump motor K. Breaker disconnect for media circulating pump motor L. Breaker auxiliary contacts for media circulating pump motor Figure 7. Components of motor controllers inside the control panel. Page 5

6 Low media level switch This switch (Fig. 8) shuts down the burner if the level of media in the expansion tank gets too low for safe operation. The switch is wired into the 3 P interlock circuit. escape. There is no opening between the float housing and the switch housing. (The float mechanism has a magnet that activates the switch inside the switch housing.) You can open or replace the switch housing without draining the expansion tank. However, you must drain the tank before removing the float housing. If the first check determines that the switch is working when closed, proceed with the second check to ensure that opening its contacts will shut down the burner. Remove the cover from the switch. Use the flat side of a screwdriver to depress the trip mechanism so as to open the switch contacts (Fig. 9). Figure 8. Low media level switch. Before checking the switch for proper operation, confirm that the expansion tank (A, Fig. 4) contains an adequate level of thermal fluid media. Do this by using a measuring stick through the filler opening (B, Fig. 4). to make sure the level of the fluid is above the spot where the switch is installed in the tank. Also verify that the float inside the tank is properly oriented by checking the bushing at the back of switch on the outside of the tank. One of the six flat sides of the hex on the bushing should be stamped with the letter T. This flat side of the bushing should be on top and should appear to be level. There are two checks that you should make to determine if the switch circuit is working properly. The first check determines if the switch contacts are actually closed as they should be when there is an adequate level of media in the expansion tank. The second check makes sure that opening the switch contacts will actually shutdown the burner as it should. To do the first check, open the control panel (Fig. 5) and turn on power to the panel while it is open. On HC and HCS heaters check for 120 V ac between terminal H50 and neutral. If the voltage is present, the switch is closed as it should be. For HCI heaters check your wiring diagram for the correct terminal number. If no voltage is present, the switch circuit is open and there is a problem with the switch circuit. Remove the screw-on cover plate from the back of the switch and see if there is a loose wire or an obvious problem with the micro-switch or the linkage that activates the switch. Otherwise, replace the entire switch, including the float portion. Note: The switch has two parts: a switch housing and a float housing. The float housing protrudes inside the tank and seals the opening so that thermal fluid cannot Figure 9. Opening the contacts of a low media level switch. Opening the switch should cause the following reactions, which indicate that the switch is operating properly: 1. Circulating pump should shut off. 2. The burner should shut down. 3. The message on the bottom line of the Fireye display module should read LOCKOUT LOW MEDIA LEVEL. Circulating pump motor auxiliary contacts This is a module with contacts (J, Fig. 7) that prevent operation of the burner unless the contactor for the media circulating pump motor is actuated (closed). The contacts are wired into the 3 P interlock circuit. The module has a plunger that opens and closes the contacts by engagement with the contactor. If the contactor opens, its plunger will open the contacts and shut off the burner. Check the auxiliary contacts as follows: With the burner operating, trip the breaker disconnect for the media circulating pump motor (K, Fig. 7). Page 6

7 This should cause the auxiliary contacts to open. The following reactions should occur, indicating that the contacts are operating properly: 2. The message on the bottom line of the Fireye display module should read CIRC PUMP AUX CT. Reset circulating pump circuit breaker. Low fuel gas pressure switch This switch (Fig. 9) shuts down the burner if the fuel gas pressure goes lower than the setpoint on the switch. The switch is wired into the 3 P interlock circuit. High fuel gas pressure switch This switch (Fig. 10) shuts down the burner if the fuel gas pressure increases higher than the setpoint on the switch. The switch is wired into the 3 P interlock circuit. Figure 10. High fuel gas pressure switch. Figure 9. Low fuel gas pressure switch. Check the switch as follows: Shut off the main gas manual shutoff valve and set BURNER switch (Fig. 6) to ON. Remove the plug from the tee fitting below the pressure switch, allowing gas to escape. switch is operating properly: Fireye burner display (Fig. 6) should read LOCKOUT 3 P INTLK OPEN. Reinstall plug in tee fitting. Slowly re-open the main gas manual shutoff valve. Reset the low fuel gas pressure switch (Fig. 9) using its manual reset button. Reset the Fireye control. Check the switch as follows: With the burner operating, remove the cover from the switch. Be careful not to touch the live terminals. Adjust the switch to a lower setting that causes the switch to open. pressure switch is operating properly: The burner should shut down. Fireye burner display (Fig. 6) should read LOCKOUT 3 P INTLK OPEN. Re-adjust the high pressure switch to its previous position and reset its manual reset button. Reinstall its cover. High media temperature controller This controller (Fig. 11) shuts down the burner if the media temperature exceeds its setpoint. The temperature controller is manually preset to a set point (SP) that has been established by the customer for the individual heater. It can be changed in the field by an operator. The controller monitors the temperature signal from a thermocouple mounted in the outlet of the helical coil (D, Fig 4). Figure 11. High media temperature controller. Page 7

8 Check the controller as follows: With the burner operating, note the PV (process variable) temperature shown on the high media temperature controller (Fig. 11). Change the SP (setpoint) to a value lower than the temperature noted. controller is operating properly: LOCKOUT HI MEDIA TEMP. Be sure to reset the controller to its previous setpoint and push SET/ENT button. Depress and hold the reset button on the controller for 3 seconds. Temperature limits of exhaust gases Each heater has a system to shut down the burner if the heater exhaust gas exceeds preset limits. Two different systems are used. One system employs a thermocouple and a temperature controller, which can be adjusted in the field. The other system uses a temperature switch instead of a thermocouple and controller. The operating temperature of the switch should not be adjusted in the field. The temperature controller is manually preset to a set point (SP) that has been established by the customer for the individual heater. It can be changed in the field by an operator. The controller monitors the temperature signal from the thermocouple, which is mounted in the exhaust stack. If the temperature of the exhaust gas exceeds the set point, the controller will open the interlock circuit and shutdown the burner. controller is operating properly: LOCKOUT HI STACK TEMP. Be sure to reset the controller to its previous setpoint and push SET/ENT button. Depress and hold the reset button on the controller for 3 seconds. Temperature switches are preset by the manufacturer to open at a specified temperature. We usually order them set for 1,000 degrees F. Although they can be ordered for other temperatures, they should not be changed in the field. The switch is wired into the 3 P interlock circuit. If the temperature of the exhaust gas exceeds the preset temperature, the switch will open the interlock circuit and shutdown the burner. The switch can be checked for proper operation as described below. With the burner operating, remove cover from the high flue gas temperature switch. Use the flat side of a screwdriver to depress the tiny button on the switch to open its contacts (Fig. 13). RESET BUTTON Figure 13. Checking high flue gas stack temperature switch. switch is operating properly: LOCKOUT HI STACK TEMP. Figure 12. High stack temperature controller. The controller and thermocouple can be checked for proper operation as described below. With the burner operating, note the PV (process variable) temperature shown on the high stack temperature controller (Fig. 12). Change the SP (setpoint) to a value lower than the temperature noted and push the SET/ENT button. Reset the switch, using the insulated handle of a screwdriver to press the reset button on the switch. This avoids the possibility of electrical shock from the exposed terminals next to the reset button. Page 8

9 Combustion air motor auxiliary contacts This is a module with contacts that prevent operation of the burner unless the contactor for the combustion air motor is actuated (closed). The contacts are wired into the 3 P interlock circuit. The module has a plunger that opens and closes the contacts by engagement with the contactor. If the contactor opens, its plunger will open the contacts and shut off the burner. Check the auxiliary contacts as follows: With the burner operating, trip the breaker disconnect for the combustion air blower motor (C, Fig. 7). This should cause its auxiliary contacts (F Fig. 7) to open. contacts are operating properly: 2. Fireye burner display (Fig. 6) should read LOCKOUT AIR AUX CT. Reset the breaker disconnect for the combustion air blower motor. Low combustion air pressure switch This switch (Fig. 14) shuts down the burner if combustion air is too low for safe operation. The switch is wired into the 3 P interlock circuit. Figure 14. Low combustion air switch. Check the switch as follows: With the burner off, unlatch the auxiliary contacts module and physically remove it from the burner circuit breaker with wires attached. Pull out the blue plunger on the module (Fig. 15) and hold it out so as to close its contacts. Figure 15. Pulling out plunger on an auxiliary contacts module. Restart the burner. Trip the burner circuit breaker. The following reactions should occur, indicating that the pressure switch is operating properly: LOCKOUT LO AIR PRES. Re-insert the auxiliary contacts module into the breaker disconnect. Fuel oil pump auxiliary contacts This is a module with contacts that prevent operation of the burner unless the contactor for the fuel oil pump motor is actuated (closed). The contacts are wired into the 3 P interlock circuit. The module has a plunger that opens and closes the contacts by engagement with the contactor. If the contactor opens, its plunger will open the contacts and shut off the burner. Check the auxiliary contacts as follows: With the burner operating, trip the breaker disconnect for the fuel oil pump motor. This should cause the auxiliary contacts to open. The following reactions should occur, indicating that the contacts are operating properly: FUEL PUMP AUX CT. Reset fuel pump circuit breaker. Page 9

10 Low fuel oil pressure switch This switch (Fig. 16) shuts down the burner if fuel oil pressure is too low. The switch is wired into the 3 P interlock circuit. PILOT GAS PRESSURE REGULATOR SWITCH Figure 16. Low fuel oil pressure switch. Check the switch as follows: With the burner off, unlatch the auxiliary contacts module and physically remove it from the fuel pump circuit breaker with wires attached. Pull out the blue plunger on the module (Fig. 15) and hold it out so as to close its contacts. Restart the burner. Trip the fuel pump circuit breaker. pressure switch is operating properly: LOCKOUT LO FUEL PRES. Pilot gas pressure regulator This regulator (Fig. 17) controls pressure of the pilot gas. The switch is not wired into the 3 P interlock circuit. Check the switch as follows: 1. Connect a manometer to a plugged fitting in the pilot gas line where it enters the burner. PLUGGED FITTING Figure 17. Pilot gas regulator and suitable pipe connection for manometer. 2. Open the control panel and gain access to the Fireye burner control (C, Fig. 5). 3. Turn on power to the control panel (F, Fig. 5) while the front panel is open. 4. Set BURNER switch (Fig. 4) to ON and let the heater start through its purge cycle. 5. Wait for the burner display (Fig. 4) to show the words IGNITION TIMING. Quickly place the switch marked CHECK/RUN on bottom of Fireye burner control (C, Fig. 5) to the position marked CHECK. This will hold the timing sequence while you check/adjust the regulator. 6. Check that the manometer indicates the correct pressure specified for your burner in the burner manual. If not, adjust screw on the regulator to attain the recommended setting. 7. Place switch marked CHECK/RUN on bottom of Fireye burner control back to RUN. The timing sequence should continue and operation should be normal. Heatec, Inc Wilson Road Chattanooga, Tennessee (423) (800) Fax (423) Page Heatec, Inc.