# MHI GAXP® Heating Element Worksheet for Furnace Design

## High Radiative Power With GAXP® Heating

Compared to SiC, very high surface loads are tolerated by GAXP.

Furnace power Calculator.

Element Power Calculator.

If you know the furnace power, please proceed directly to Element Calculators. If not, please follow the steps below.

## Steps for calculating the total length of MHI GAXP® heating elements for a new furnace.

### Step 1. Power Required.

Please size the furnace interior. Now use the furnace calculator on GAXP® to determine how much power is required for the furnace at the maximum temperature.

### Step 2. Additional Power Required?

Make further power corrections if the planned furnace insulation is weak or a high heat-up rate is required. Adding about 50% more than the calculated power in Step 1 may be ideal if the insulation is inadequate.

### Step 3. Determine the Shape and Size of Individual Heating Element

The Choices are Dumbbell, U- Shaped, or Coil Shapes

U-shaped elements are hung from the furnace roof or the furnace sides. Dumbbell elements are used in a horizontal position inside a furnace. Schematics of various configurations inside a box. Coils may be hung from the roof.

Furnace use is discussed below under step 5 in ‘More Resources.’ Calculate the total GAXP® element heater length required by choosing a shape and sizing it to your furnace.

The calculator will also show the total power for the number of heating elements considered. Please ensure that the total power is equal to the Step 2 result.

Each heating element will need ceramic holders (HW3) and connection straps BW200-C).

### Step 4. Electrical Connectors.

Please visit GAXP Element Connectors – U or Dumbbell Shape (or use Coil Accessory Packet for MagnaCoil heating elements) for electrical connectors.   Prices of connectors are also shown for each accessory pack.

### Step 5. Tips.

The cold (terminal) section, Lu, should be at least a few inches larger than the insulation to properly connect your electric (braided wires). Connections must not get hot during use. Good furnace manufacturers use strong fans to keep the terminal area (electrical connections region) cool.

### Step 6. Consult Resources.

Contact MHI for a final check. MHI can advise on the control system you may need (BPAN, XPAN, or TRIPAN). BPAN prices are listed in the MHI store. When purchasing a control panel, please ensure features like soft start and current limits. Please use a power transformer that matches the voltage of the furnace.   MHI can also provide a certification logo for the furnace.

# Use GAXP® heating elements

1. Nanostructured element. Patented material from a well-respected supplier in business for twenty years.
2. Typical shapes: Hairpin shape (same as U-shaped), Dumbbell (same as straight), or Coil. (See schematics pictured below).
3. For use in air (oxidation), carbon (reducing), neutral, or combustion atmosphere. (The GAXP® is a patent-protected technology product).

Coils may be used for any temperature. For temperatures <1000°C, the Dumbbell shape is allowed. For temperatures over 1000°C, use the U-shaped heating elements. For coils, contact MHI for assistance.

GAXP® heating elements are considered for change-out in many SiC heaters, especially where a higher element life and modern controls are required. MHI warrants its GAXP heating elements.

*Furnaces should be constructed only by an experienced furnace maker. Please observe all safety rules/practices commonly associated with high temperature, high voltage, and high current. Always please use only industry-approved insulation.    Please use high-temperature safety