Disclaimer:
The following information is for amusement purposes only. Only professionally trained persons should attempt to build these heaters and all persons fully understand and accept the responsibilities and all consequences of damages resulting from short circuits, health risks, high currents, high temperatures, fires, explosions, equipment damage, electrocution, and any other consequence which results from novice experimentation.


Required Parts:
Qty Description
1 . . Discarded/used electric stove burner (free)
2 . . Spade Connectors, Tinned Steel, electrical (~$0.50)
1 . . 2-part epoxy putty, *** 500F ***, Walmart (~$3.50)


Theory of Operation:
The electric burner has a stainless steel shell that is electrically isolated from a heater wire that runs through the center of the burner by a chalk-like compound (possibly Asbestos).

The wattage produced by a heater is a function of the voltage and its length. A standard burner is 240V and it's length as an example 20" which will make the burner cherry red. If the burner is cut in half, then 120V will make the burner cherry red. Divide 120V by 10 and you have a 12V burner which is 1" long.

By choosing heater elements that are longer, like the oven element, a 12v tubing heater can be made in a similar fashion that is longer. The shorter the desired burner, the more difficult it will be to control the maximum temperature achieved.

We do NOT want a tubing heater that is cherry red !!!!!! So we choose a length longer than the design minimum length for the heating element at 12V. If a 1" element is cherry red, an 8" element might be closer to the temperature we want our tubing to be.

You are the designer, you will have to choose how hot, how long, how much current your electrical source can provide, how to mount it, what might be damaged, etc.


Safety Precautions:
Use rubber gloves and a mask when handling this compound because it is likely to be Asbestos.

Fuel or moisture trapped inside the heater element may explode when voltage is applied. Be sure to test your heaters behind a protective shield.

Electric shock can occur and proper handling is required.

Heating oil may cause explosive vapors to form.

Bending the tubing may significantly shorten the life of the heater.

Handling or breathing epoxy fumes may cause health problems; use gloves in a well ventilated area.

Be sure to use good electrical practices for the temperatures being produced.


How to build a 12-volt heater strip:
Put on protective gloves, mask, and lay down disposable plastic protective surface to work on.

Take a used 240V stove burner element and cut a section 12" in length with a hacksaw (a 2-jaw vise helps). Carefully cut the diameter of the burner sheath 1" from each end by rolling the tubing and cutting just through its surface. Then slide the burner sheath off each end. This will expose the delicate heater wires near the center of the burner tubing.

Support strips are fabricated using the stainless steel sheath by providing surfaces to better secure the epoxy putty to during assembly. Carefully saw one inch length-wise along the edge of two parallel sides to create two parallel metal strips (two parallel tubing faces will be left intact with the heater wire between them).

Straighten the coiled wire from the edge of the crimp-on to where the heater wire enters the stainless steel tubing. Crimp on a tinned-steel electrical spade connector on each end of the heater wire allowing for about 1/4" between spade and burner tube. Do NOT use aluminum spade connectors; they loosen when they get hot.

Take 500F epoxy putty and knead it in your hands until a homogeneous consistancy.

Apply the putty around the spade connectors and burner ends to support the spade connector and seal the burner ends. Do NOT let epoxy interfere with the slip-on portion of the electrical connector. Do NOT allow heater wires to come in contact with stainless steel burner sheath. Attempt to minimize the amount of putty which will raise your heater off of the surface you are going to heat. (See photo of completed heater strip)

Use epoxy to fill in around straightened heater wire and crimp-on, lay tubing strips upon epoxy, then fill in around tubing strips.

Everything to this point is about 5 minutes of work. Though the first one will probably take longer because of inexperience.

Let the epoxy cure for 2 hours; both ends can be done at the same time.

That's it !!!!!!!!!!!!

The picture shows the original end provided by the manufacturer and the spade connector that was mounted with epoxy.

Dispose of anything that came in contact with the white compound inside the burner. It may not be Asbestos, but don't take a chance.


Testing:
Determine the maximum voltage that will be applied to the burner; don't forget charging system voltage is higher than battery voltage.

You might wear a welder's helmet when you first energize your burner. Trapped gases or high currents might cause burner to explode, though this is unlikely, take precautions, you are experimenting with something you don't fully understand.

Determine the maximum temperature allowable for the materials intended to be heated.

Test the heater to be sure those temperatures will not be exceeded during the worst case conditions.

Make the burner longer to lower the temperature, or shorter to increase the temperature.

If more heat at a lower temperature is desired, make multiple burners and construct them in parallel.


Mounting:
The stainless steel housing of the burner is electrically insulated from the heater wires, so you can attach the heater to metal surfaces directly.

Use a couple of stainless steel hose clamps to attach your heater to whatever you want to heat. You can bend the burner slightly and then secure it with hose clamps to get continuous contact with the surface of interest.

You may be able to use a high-temp cutout from a furnace to limit the maximum temperature reached by the heated surface; that's up to the experimenter.

Do NOT attempt to heat paint, plastics, or rubber; they are poor conductors of heat. They can melt and the heater may cause a fire.

Test your system carefully to ensure safe conditions for people and the equipment with which they interface.


Durability:
Only experience will teach you the tricks for making burners that last a long time.

Try not to bend burners too much.

If burner has been cut open for more than a couple of hours, heat it up in an oven to 400F before assembling another burner to get rid of any moisture, fuel, and combustible gases before sealing the ends of the burner. There shouldn't be any, but take precautions.



Good luck and remember to take all due precautions.

This message has been edited. Last edited by: jamesbdunn,

Heater_12v_01.JPG (31 Kb, 418 downloads) A 12V fuel line heater

Pictures?

quote:

Originally posted by bcaufield:
Pictures?

Epoxy500F.JPG (66 Kb, 336 downloads) Wal-Mart 500F Epoxy

Cut off a chunk and fold/knead it until it is a uniform color.

EpoxyComp.JPG (24 Kb, 269 downloads) Two-part Epoxy