Formed Tubular Heater

Formed means more heated length in less space

Say you have a tank only 40 cm deep but you need six kilowatts. With a straight 400 mm element the watt density climbs so high that the element will not last. Bend the same element into a U and the heated length doubles while the watt density halves. This is the simplest and most common reason to choose formed.

What the drawing needs on it

So we can build without going back and forth, put these figures on the drawing: the length of each leg, the centre-to-centre distance between legs, the bend radius, the sheath diameter, the cold end length, the power and voltage, and whether the termination is a stud or a lead wire. If you send a physical sample instead, we take the same measurements off it.

Do not put the bend in the hottest place

We normally design the bend as cold or low-wattage, because through a curve the distance from the resistance wire to the sheath is not the same on both sides. If you send a drawing that puts the bend right in the middle of the high-power zone, we will tell you and suggest a change.

Ring and spiral shapes

A ring suits heating the bottom of a round tank evenly. A spiral suits small heat exchangers and pre-heaters. Both cost more than a U, because there are more bending steps and holding the dimensions is harder.

What cannot be changed afterwards

A formed element is effectively unalterable once made. Opening out or reshaping a bend wrecks the insulation inside. So we go over the dimensions with you once more before production — those few minutes prevent a rebuild.

Fitting and looking after it

Never hold or lever a formed element by its bend. When fitting, take the weight only on the cold end or the flange. If it goes inside a tank, fix the brackets so the element can grow slightly in length as it heats. Clamping it completely rigid will crack it after a few heating and cooling cycles.