A Look Inside the Furnace: Removing the Hot Zone

Ipsen hot zone installation

When the time comes to remove your old hot zone in preparation for installing a new one, it is important to use caution to avoid damaging your equipment. Below are some recommended steps and tips for successfully completing the removal process.*

*Note: These steps are specific to certain types of furnaces such as the Ipsen TurboTreater®, TITAN® and standard horizontal models. Regardless of your hot zone and furnace model, we recommend consulting your furnace’s manual or customer service expert before beginning the removal process.

1. Place the furnace into a safe condition.
  • De-energize the circuit breakers to the main furnace and hot zone.
  • Follow standard lockout/tagout (LOTO) procedures.
2. Remove thermocouples (TCs).
  • Use tape or a marker to mark the TC shaft where it enters the vacuum fitting; this allows you to position the TCs at the same depth when reinstalled.
Removing thermocouple
  • Loosen the nut on the fitting just enough to allow the TCs to be removed.
  • Remove the TCs and inspect the shaft for breaks or kinks.
  • Store the TCs in a safe place to prevent damage until you’re ready to install them in a new hot zone.
3. Remove the load support hearth system.
  • Remove all components of the system (i.e., rails, caps, posts).
  • If the hearth posts will be reused, it is advisable to note where each of the posts is located in the furnace so they can be put back into their original positions.

Expert Tip: Be careful to leave the shims inserted in the hearth-post sockets for use when installing the new hearth.

4. Remove power feedthrough assemblies.
  • In the hot zone, disconnect the heating elements from the power feedthrough bars.

Expert Tip: The moly nuts holding the element connectors to the bars will most likely break during removal; it is advisable never to reuse moly hardware (new nuts and rods are typically included with the new hot zone).

  • From the outside of the furnace, remove the VRT/SCR secondary cables from the power feedthroughs.
    • Inspect all cables and copper feedthroughs for signs of arcing and/or cuts in the cable insulation.

Expert Tip: It is a good idea to mark each of the cable locations before removing them from the power feedthroughs; this will help ensure they are reinstalled in the same location.

  • Unbolt the power feedthrough block and pull it away from the furnace.
  • Disconnect and discard the moly bars from the power feedthrough block. 
5. Determine which type of hot zone seal you have – bolted or slip – by referring to the gas-system assembly drawing in your furnace’s manual.

A bolted seal, such as that on an older TurboTreater furnace, will require additional steps, including removing the motor cover and disconnecting bolts that are connected to the hot zone transition plate.

Slip-seal hot zone
  • If you have a slip-seal hot zone, skip to step 6.
Bolted-seal hot zone
  • Disconnect all water-feed and drain lines from the copper tubing penetrating the motor cover.
  • Remove the vacuum seal fittings from the ports on the motor cover and slide them off of the copper tubing.
    • These fittings utilize a nylon or rubber ferrule to prevent vacuum leaks around the copper tubing; ferrules should be replaced when reassembling the motor cover.
    • Straighten all of the copper tubing as much as possible to allow for easy removal of the cover.
  • Remove the bolts from the motor cover.
    • Prior to removing all of the bolts, support the motor cover, by either an overhead crane or a forklift.

Expert Tip: As the last bolts are removed, balance the motor cover to prevent it from swinging while being suspended and pulled away from the furnace.

  • Move the cover away from the furnace, all while being very careful not to bend, kink or pull out any of the copper tubes. Too much pressure against the tubing could cause a leak in the lines.

Expert Tip: When the motor cover is removed, this is also a convenient time to clean the motor and schedule other routine maintenance that will help extend the life of the cooling system’s components.

  • Remove the lock nuts and washers that attach the back of the hot zone to the transition plate.
    • Use a long extension (48”) to reach the transition plate. The nuts are approximately even with the fan blade surface and can be seen by looking through the back of the motor housing.

Expert Tip: Be sure to account for all nuts and washers. Loose parts that are lying near the fan when it starts could cause severe damage to the cooling coils.

6. Remove the head pack from the front door to allow for more space and prevent it from being damaged when removing the hot zone.
  • Support the head pack frame with an overhead crane or forklift prior to removing all of the fasteners. Be prepared to balance the head pack as the last fasteners are removed and it is pulled away from the supports.
  • Remove the wire locking pins and hex nuts that connect the head pack to the door in all locations.

Expert Tip: Make a note of the distance from the flange to the back of the head pack to ensure the new pack is placed in the same position when reinstalled.

7. Remove the hot zone from the furnace.
  • Removing the hot zone requires a 10,000-pound forklift with approximately six-foot fork extensions to support the hot zone.
    • It is beneficial to have a forklift with left-to-right shifting capabilities in order to assist with positioning the hot zone for removal.
  • Prior to lifting, pull the hot zone forward (out the door) about two inches, which allows the bolts to clear the transition plate (for bolted-seal hot zones).

Expert Tip: Lift the hot zone straight up approximately one inch and into a level position to ensure the hot zone’s weight is fully supported by the forklift. This helps prevent it from tipping when it exits the furnace.

Once the hot zone is safely removed, clean the inner chamber walls and replace the ductor seal gland and jack panel assembly. Once you have done so, the furnace should be ready for the installation of a new hot zone. The installation process is similar, but in reverse and with a few exceptions and details that should be noted.

For more information or further assistance with removing a hot zone, as well as quotes for new hot zone installations on most furnace brands, you can contact Ipsen Customer Service at 1-844-GO-IPSEN.