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Deep Fryer Hi Limit Replacement Instructions

The hi-limit is a vital safety part in hot-side equipment. Without it, everything from fryers to ovens could run the risk of overheating to dangerous levels. So, if you show up to a job site and the part clearly isn’t working, it could be time to swap it out for a new one. If it’s your first day on the job or you’re a senior tech in need of a refresh, these deep fryer hi-limit replacement instructions should help you get the job done.

Diagnosing a Deep Fryer Hi-Limit

Before deciding whether to replace the part or not, you need to properly diagnose it first. 

  • Step 1. Unmount the hi-limit – Start by removing the thermostat knob. Then remove the two screws securing the thermostat and hi-limit bracket to the fryer. Once that is done, loosen the two screws that secure the hi-limit to the bracket and remove it. 
  • Step 2. Check for continuity – Using a multimeter, check the hi-limit for continuity to verify whether it is working as it should. 

How to Replace a Commercial Fryer Hi-Limit

If it has been determined during diagnosis that the hi-limit needs to be replaced, power down the unit, drain the oil and wait for the unit to cool. 

  • Step 1. Disconnect the wires – Connect the two wires from the hi-limit by loosening the screws that secure them in place.
    • Note. Take note of which wires connect where so they don’t get mixed up when installing the new hi-limit. 
  • Step 2. Remove the burner – To better access the stuffing box and capillary, you can remove a burner.
    • Note. Be sure the burners are cooled before touching them.
  • Step 3. Unmount the temperature-sensing bulb – Go up the vat to loosen and remove the screw mounting the temperature sensing bulb. 
  • Step 4. Run the temperature sensing-bulb down – Loosen the stuffing box so you can pull the capillary down and through the hole. At this point, the old hi-limit has been fully disconnected from the fryer.
  • Step 5. Connect the new hi-limit – Take the two wires and connect them to the new hi-limit. Use a screwdriver to tighten the screws that secure the wires in place.
  • Step 6. Remount the hi-limit – Secure the hi-limit back onto the bracket by reinstalling the screws. Then, mount the bracket back into place on the fryer. 
  • Step 7. Run up the capillary – Run the temperature-sensing bulb capillary back up the whole and hand tighten the stuffing box so you have some slack when mounting the bulb up top.
    • Note. Be gentle with the capillary to avoid damaging it.
  • Step 8. Mount the temperature-sensing bulb – Without kinking it, mount the temperature-sensing bulb. Make sure it’s positioned to not touch the side walls of the heat exchanger.