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Frequently Asked Indirect Heater Questions


1. Is ETL the same as UL?
  Yes, both are Nationally Recognized Testing Laboratories that test, certify and inspect products for safety and performance for manufacturers. The standard to which CAS hoods are tested is UL 710, Exhaust fans are tested to UL Standards UL 762 & UL 705 . All Indirect-Fired units are tested to ANSI Standard Z83.8 by ETL. You can visit this link for a comparison.

2. Dust and pollen is coming through the supply duct.
  Super Filter Coat is a water soluble adhesive applied to the mesh filter after each washing. The adhesive is characteristic of fly paper as it will trap the dust and dirt particles from the airstream. This is available from our website. It is part number 412.

3. How does the Remote Heater Control Panel work?
  The 'Manual/Off/Auto' switch determines how the heat is turned on and off. If this switch is in the 'Manual' position the heat is turned on and off by the 'Heat/Vent' switch. If it is in the 'Auto' position it is turned on and off by the intake air thermostat located in the unit on the roof. When the outside temperature falls below the set point of this thermostat the heat comes on and shuts off when the temperature rises above it. There are two configurations available for this remote panel, a 3-position and a 2-position. The 'Off' position will turn the blower off on a 3-position panel. On a 2-position panel it only turns off the heat, the blower is controlled by another panel.

4. Makeup heater blower runs but heat will not come on.
  Check high limit reset if tripped reset. Check temperature setting on heater 'ON' thermostat. The setting must be higher than the outside air temperature. If there is a remote control panel, check the switch positions. They should be on 'Manual' and 'Heat'. If the air flow is not within the performance range of the unit the heat will not come on. Air flow can be reduced by clogged filters, collapsed duct, or closed outlet dampers.

5. Makeup heater has power but fan will not turn on.
  If the unit has a damper verify that it is opening. It has to be fully open before the blower will operate. Check the overload and circuit breaker in unit and reset if tripped.

6. The supply fan is not performing as well as it did in the past.
  This could be the result of a loose or worn belt. Other possible causes are dirty or clogged filters located in the unit on the roof.

7. The fan overload trips.
  The overload provides protection for motors without internal thermal protection. This is on all three phase and large single phase motors. If a motor over amps or the current draw on the incoming power leads is unbalanced the overload will trip. Overamping can be the result of using a motor not large enough or running the fan at higher RPM's than needed. If you can slow the fan down this should be your first choice. If this is not an option replace the motor with a larger HP one. Unbalanced loads can be the result of a defective motor or unbalanced power supply. If one of the lines of a 3-phase power supply has lost it's voltage the motor will run on only two lines and overamp. Another common cause of overload tripping is a lightning storm or power outage. When the power comes on again voltage is usually low because of the great demand on the power grid. As voltage goes down the amperage goes up and the overload trips.

8. The fan motor shut off and starts again after several minutes.
  The motor is probably shutting off on thermal overload. The motor is overheating and restarts after it cools down and the thermal overload resets. This only happens with single phase motors that are thermally protected. The name plate will tell you if it has internal protection. First measure the amp draw while the motor is running and compare it with the nameplate. If it is not much higher you may only need to slow the fan down until it is at or below the running amps indicated on the name plate. If slowing the fan down is not an option you need to replace the motor with a larger HP motor. Lastly it could be a defective motor.

9. The fan is vibrating. What is wrong?
  Several things can cause vibration. Before assuming the wheel is unbalanced, check other possible causes first. Look for any obvious signs of a rag or foreign object stuck in the wheel. Another common problem is the fan was recently cleaned and not all the grease was removed from the wheel causing it to be out of balance. Mechanical problems can be the motor, belt, bearings, or wheel. Remove the belt and run only the motor if it vibrates replace motor. Check the belt. If it is in poor condition replace. Make sure the blower pulley and the motor pulley are in alignment. Check bearings for wear or damage. They may also need lubrication. Finally make sure that the fan is secured to the curb. Just adding an extra screw can sometimes quite a noisy fan. If a fan is operating outside its performance range it will also vibrate.

10. How do you replace a pulley?
  Single groove pulleys are usually easy to remove after loosening the set screw. Larger pulleys that have a tapered compression bushing are removed by taking out the two hex bolts and placing them in the other two holes. When tightened the bushing will pop out and the pulley can be removed. When replacing make sure the taper of the pulley and bushing match.

11. How do you adjust a pulley?
  There is an adjustable sheave on the motor. There are two hex set screws on the pulley. One secures the pulley to the shaft. The other allows the two halves of the pulley to be adjusted closer together or further apart. Be sure when adjusting retighten the set screws on a flat side of the pulley base. Adjusting the halves closer together increases the fan speed, further apart slows it down. Double grove pulleys must be turned the same number of turns or the belts will not seat properly in the groves. Always check motor amperage after adjusting pulleys.

12. The supply fan will not turn on.
  If the hood system was provided with our control panel the system is probably in fire condition. In this mode the exhaust fan will not shut off and the supply fan will not come on. Other possible causes are the R1 relay is bad in the control panel, or the contactor coil is open.

13. The heated makeup heater works fine on a mild day but blows cold air on very cold days.
  The high fire limit is set too low. Refer to operator's manual and readjust.