- The LP or Natural gas fuel supply does not have enough supply to increase temperatures past a given point, contact the utility company.
- Modulating valves will not adjust temperature to give proper increase in chamber temperature. Remove bulb from heat and put into ice or a cool place and restart the burner. The burner should go to maximum output and trip off high limits if you do not control temperature with hand valve. If temperature does not go to maximum and stays where it was before exposing bulb to cold temperatures, then power element is bad and must be replaced.
- Proportional valve may not be opening to allow more fuel to burner. Proportional valve has a clear cover and slot cut into shaft. Actuator is orange Belimo valve and will rotate slot from shut position, slot is 90-degrees from pipe train. In the open position, slot is in line with pipe train. This is controlled by 0-10 DCV signal and 24 DCV to run motor, check Belimo for voltage. 1 to 2 is 24 DCV and 1 to 3 is 0-10 DCV at the Belimo actuator.
- Check gas pressure gauges for pressure while running burner, loss in pressure can result in a loss in chamber temperature. If gauges are not properly working they need to be replaced.
- If no pressure is shown on gauges, check solenoids for opening. 120 volts to a solenoid should open coil and diaphragm.
- If solenoids are opening and no pressure is indicated on the gages, check hand valves for open position and check LP strain filter to see if it is plugged.
- If burner is operating and flame looks small, check air inlets and/or burner orifice for obstructions. Maxon burner holes could be corroded and need to be opened up with drill bit.
- Ignition board is not providing high voltage for spark. Faulty board.
- Missing eddys or baffles, especially for natural gas.
- Holes plugged on Maxon or Midco burners, especially in the area of the electrode.
- Air pressure was never achieved, adjust air pressure switch once fan is running.
- Check 120 volts with volt meter at terminal L1 on ignition board.
- Check spark plug or igniter for proper 3/16” to ¼” gap and porcelain is intact.
- Check that wire is in good shape with no breaks or insulation missing.
- Check 120 volts with volt meter at terminal V1 on ignition board, with wires pulled off of V1. Power is only on V1 for trial for ignition 7 to 10 seconds, identical time that gas valve light is ON.
- Check 120 volts with volt meter at terminal V1 on ignition board, with wires re- attached to V1. If no voltage is present then solenoid coil or gas valve light is bad and needs replacing.
- If power is at L1 to board and is never at V1 power leaving board, then board is bad and needs replacing.
- Power at L1 and V1, gas controls are all operating, and then check gas pressure gauge is working and changes with trial for ignition.
If you can light a burner and flame extinguishes after 7 to 10 seconds, then we are not sensing the flame is present.
- Make sure dryer is properly grounded to chassis of dryer.
- Check the flame sense probe & wire, to make sure it is not damaged.
- Check wire from S1 on ignition board to flame sense probe, replace it and do not try to repair wire.
- If a lot of moisture is present around flame sense probe, a rubber boot might need to be added to protect terminal ends.
- Re-adjust flame sense probe to ensure flame emersion.
- Possible faulty ignition board.
If you can light and maintain flame for longer period of time than 7 to 10 seconds, then the ignition board is sensing flame is present but then dropping out flame after a little time of running.
- Burner is not adjusted properly and must be adjusted until flame is mostly blue with small portion of orange.
- Pressure is too high and pulling away from burner face or ground rod.
- Chassis ground is not properly bonded and ground is intermittent.
- Modulating valve is not functioning properly and closing down too far. The modulating valve is designed to hold a given temperature or set point that can be adjusted. If the valve cannot hold a temperature then the power element on bottom of valve needs to be replaced.
- Check fuel supply for flow restrictions.
Burner maintenance is of highest importance to keep your dryer running efficiently. First, make sure ALL power is turned off and LOCKED OUT! (You’re going into the heat chamber; take no chances!) Make sure the burner covers are removed if cleaning a tower model. Vacuum or blow out the accumulated dust and beeswings (or red-eye). Try not to simply wipe the residue as it will further clog the burner openings, and when you clean out the holes the residue goes into the plumbing train. When the burner is ignited, all that residue re-plugs the holes in the burner.
TWO BURNER TYPES: Maxon & Midco:
MAXON BURNER – To clean the Maxon burner you will need two different size drill bits: One a size # 47 (5/64), and the other a size # 50. They can be easily obtained locally or Grainger has them as item numbers 1V 818 and 1V 825. (They are really small and brittle, take a few of each.) Use them to open the holes in your burner, being careful around the spark plug. A cordless drill works well, but remember the bits will break easily. A cutting torch tip cleaner (drill bit type) also works well.
MIDCO BURNER – If you have the Midco burner its the same procedure, just use a 1/8 inch bit for the gas holes and a # 42 for the air holes (Grainger has them as item numbers 5 TG 11 and 22 N 359).
While you are there it’s a great time to inspect the spark plug and flame sense rod to make sure they are still in good shape. A flashlight is a good item to take with you. Once finished, re-apply power and test fire the burner (jumper the air pressure switch), to make sure everything is ready.
This one simple thing will save many problems in getting your burners lit and it will also make them burn more efficiently.
- First go to the CAL temperature controller and verify that it works. Is the top number (green) that shows the plenum temperature accurate? Can you change the set point, the bottom number? When you change the set point, does the gas valve actuator respond appropriately?
- If the above are true, you can still operate the burner by monitoring and controlling with the CAL if you cannot control and monitor from the HMI?
- Have your dealer’s service rep check for the proper address in the CAL parameters.
- Replace the CAL controller with one that has been loaded with the proper parameters and communication address.
- The gas pressure is probably too high. Reduce gas pressure via the regulator until the gas valve actuator settles down and operates at approximately 30% to 50% open.
Why on the CAL temperature controller and on the HMI screen, the plenum temperature is a negative number when it is obviously not that cold.
- Check connections of the signal wires to the RTD or Thermocouple, at the terminal blocks, and at the CAL.
- Possible bad RTD or thermocouple.
The plenum temperature as shown on the HMI and on the CAL controller does not seem accurate. What’s the fix?
- Use a temperature testing device and place its probe in the same place as the dryer’s RTD or thermocouple and observe the difference.
- When the dryer is empty, the temperature shown on the CAL or HMI should be within a few degrees of actual ambient. Be aware that the sun shining on the dryer can cause some difference.
- If the difference is more than a few degrees, replace the RTD or thermocouple.
- If fueled by LP, check for a hole in the vaporizer or a leak in any of the pipe connections.
- Check for dirt in the solenoid valves, holding them open.
- Verify that the dryer is full of grain at all times.
- Verify all hatches are closed.
- Check for leaks in the plumbing, especially inside the dryer.
The Bleimo brand of actuator is not responding to what is shown for percentage open on the plenums page on the HMI.
- At the terminals on the Bleimo, check for 24vdc between the red and black wires. Check for 0 to 10 vdc between the white and black wires. This voltage should correspond to the percentage of valve opening as shown on the plenums screen on the HMI.
- The actuator assembly might be bound up. Crack loose the single mounting screw found on the bottom of the box to allow the box and actuator to have a little movement.
Check if the CAL is programmed for Centigrade instead of Fahrenheit.
A “Plenum Low Temperature” shutdown alarm is shown on my HMI screen. After I accept this alarm, I cannot clear this alarm by pressing Reset on the plenums page.
- Turn the ignition switch off. The CAL temperature controller itself must be reset by momentarily turning off the 120vac supplying it. This may be done by pushing the High Limit and Air Pressure amber lights at the same time for about one second.
- Is the gas source adequate? Are the supply lines large enough?
- Check for water in the lines by checking at the drip legs.
- Check that all valves are functioning properly.
- Check strainer.
- Check for adequate pressure provided by the regulator(s).
- Burner holes need cleaning. A visual inspection is not adequate. You must physically probe each hole. A Maxon burner uses to different hole sizes. They are drill size #47 (5/64”) and #50. A midco burner has 1/8” gas holes and #42 air holes.
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