Tubular heating elements are inserted into a milled slot into the manifold. This allows for a more accurate location of heat at the areas that require the most (i.e., nozzle exits).

Tubular heating elements are for the most part the heater of choice. They are reliable, relatively inexpensive and there is no extra cost for gun drilling the manifold. But more importantly, they perform the job well.

Tubular heaters do have two drawbacks. One is availability. It can take from six weeks standard delivery to as little as a week (if the manufacturer is running that diameter that week) to get a new part. Unlike cartridge heaters, tubular heaters have longer delivery times because of the machine setup time.

The other drawback is the design. If the manufacturer does not have a template of your system, it is extremely difficult to match some of the more complex layouts. For this reason, more companies are changing to highly flexible tubular heaters. These can be easily inserted into a manifold by anyone, resulting in shorter down time. This type of heater is capable up to 95 watts per square inch and is easily bent on site in minutes. A stainless steel plate or insulation plate is recommended to hold the heaters in place, and a dovetail design can replace this plate if a space is not available.

The thermocouple location should be maintained as explained above. If a problem arises with standard transfer heaters, it may be that the terminal area is not manufactured to bendable environment. Also, the slot may be too large or the diameter tolerance of the heater may be too wide, giving an uneven notch and an uneven temperature.