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Industrial Electric Heating

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Industrial Electric Heating covers immersion, circulation heaters, process air, industrial unit and area heaters, tubular and finned-tubular elements, bolt heaters, refrigeration defrost heaters, switchgear and enclosure anti-condensation heaters, Mil-Spec and Marine-Duty heaters, heater control panels with SCR power controllers and step controllers/sequencers, Sure-Steam steam-sterilizer wet-pack prevention, heat trace, impedance pipe heating, medium-wave infrared panel heaters, and custom flexible heaters. Prater Technical Partners is the authorized representative for Indeeco, Heatrex, Accutherm, and Solar Products (the Aspeq Heating Group brands) across New York (NYC and Long Island), New Jersey, Maryland, Delaware, and Northern Virginia, and the authorized distributor for Hi-Heat across the Northeast and Mid-Atlantic. Virtually every product is custom build-to-order and quote-only — there is no published price list.

Process & Industrial Heaters — Indeeco · Heatrex · Accutherm
Mil-Spec & Marine Duty — Accutherm
Heater Control & Power Systems
Medical & Healthcare Steam Systems — Indeeco
Pipeline Heating — Indeeco
Infrared Process Heaters — Solar Products
Flexible Heating Elements — Hi-Heat

FAQ: industrial electric heating

How does an electric process heater work?

An electric process heater converts electrical energy to heat by resistance heating (a/k/a Joule heating): current passes through a high-resistance alloy element — typically an 80/20 nickel-chrome coil — and the element's resistance dissipates that energy as heat. In an industrial heater the resistance coil is rarely bare; it is embedded in compacted magnesium-oxide (MgO) insulation inside a metal sheath, which transfers the heat to the process while electrically isolating and protecting the coil. That sheathed element is then arranged for the job: bundled through a threaded-fitting or flange to heat a tank (immersion), built into a vessel that fluid flows through (circulation), or banked inside a duct to heat air (process air). Because the heat is generated at the point of use with no flame and no flue, an electric heater delivers essentially all of its input energy to the process.

Which heater type do I need — immersion, circulation, or duct/process-air?

It comes down to what you're heating and whether it moves:

  • Immersion — the element sits directly in a tank or vessel of liquid (or gas). Use it to heat a contained volume in place: storage tanks, process vessels, oil reservoirs. Mount by flange, screw-plug, or over-the-side (detailed below).
  • Circulation (inline) — an immersion element inside its own insulated pressure vessel; the fluid flows through and leaves at a controlled outlet temperature. Use it to heat a flowing stream — process skids, fuel and gas lines, heat-transfer loops. Indeeco circulation heaters cover roughly −50 °F to 1200 °F.
  • Process air / duct — elements banked inside a forced-air path to heat the air stream in an oven, dryer, autoclave, or duct.

If the medium is stationary, immersion; if it flows and you need a controlled outlet temperature, circulation; if it's air, process-air.

What is watt density, and why does it matter so much?

Watt density is the heat output per unit of element surface area — watts per square inch. It is the single most important number in heater design, because it sets how hot the sheath runs, not just the process. Drive too much wattage through too little surface and the sheath overheats: it cokes and fouls viscous oils, scales hard-water service, damages heat-sensitive fluids, and shortens element life. The fix is to spread the same wattage over more element surface — a lower watt density. Clean water tolerates a high watt density; heat-transfer oils, fuels, and viscous or high-purity fluids need a low one; air heaters can run higher densities with good airflow. This is exactly why most industrial heaters are engineered rather than pulled off a shelf — the watt density has to match the fluid.

How do I size an electric heater (what kW do I need)?

Heater kW is the sum of three loads: the energy to raise the process to temperature within the required time (mass × specific heat × temperature rise ÷ heat-up time), the energy to hold it there against standing heat losses through walls, insulation, and openings, and any energy carried away by process throughput (fluid flowing in cold and leaving hot, or material being processed). Add a safety margin for voltage variation and worst-case ambient conditions. Two values drive the answer and they are easy to get wrong: the required heat-up time (faster heat-up = more kW), and the watt density the fluid will tolerate (see watt density, above), which can force a physically larger heater than the kW alone implies. Give us the fluid, volumetric flow rate, start and target temperatures, time, and voltage available, and the heater is sized from there.

What sheath material should I choose?

The sheath is the element's only barrier against the process, so it's chosen for chemical compatibility and temperature, not cost alone. As a general guide: steel for clean water and low-corrosion service; stainless steel (304 ss) is the default for all Indeeco/Heatrex/Accutherm elements for mildly corrosive liquids and most general process work; Incoloy for high-temperature service and harsher chemistry, including many oils and high-temp air; titanium for chlorides, seawater, and aggressive plating and process solutions; copper when preferred. The wrong sheath corrodes or fails early; the right one lasts for years. Sheath choice and watt density together are what make an immersion or circulation heater fit its fluid.

Immersion heater — flanged, screw-plug, or over-the-side?

Three mounting styles, three use cases. A flanged immersion heater bolts to a matching flange on a tank or vessel nozzle — the choice for larger heaters, higher pressures, ASME-code vessels, and hazardous-area service, where flange ratings and enclosure types matter. A screw-plug heater threads into an NPT coupling — compact and economical for smaller tanks and lower-pressure service. An over-the-side heater drops in through the top of an open tank with the element along the bottom or side — it can be added or removed without draining the tank, which makes it an easy retrofit and maintenance-friendly option. Another ‘replace without draining the tank’ option for after the initial install is the “Tank Heater series” which mounts a panel to the side of the tank with through-panel tubes that carry open-coil elements — also letting the elements be replaced without draining the tank. Match the style to the vessel: a nozzle and pressure rating point to flanged; a small threaded boss points to screw-plug; an existing open tank you can't drain points to over-the-side or through-wall tank heater.

How do I heat a hazardous (classified) area or a flammable process?

Any heater going into an area with flammable gas, vapor, or combustible dust must be rated for that classification — a standard heater is an ignition source. The element is the Class, Division, and Group: Class I for flammable gases/vapors (oil and gas, petrochemical, solvents, paint spray), Class II for combustible dusts (grain, sugar, coal, metal powders), Class III for fibers; Division 1 where the hazard is present in normal operation, Division 2 where it's present only under fault; and the Group narrows the specific gas or dust. The terminal enclosure, the sheath and shell temperatures (must know Area auto-ignition T-code temperature rating), and the build all have to suit that rating. Indeeco flanged immersion heaters carry CSA Class I Div 1/2 and Class II Div 1 ratings plus ATEX/IECEx Zone 1/21 marking; Accutherm Series 72 heaters are built specifically for hazardous-location and marine duty. Give us the area classification, area T-code and process variables (see 'How do I size an electric heater' above) — never approximate a hazardous-area rating.

How do I control an electric heater — On/Off Contactor, SCR, Step controller/sequencer with optional Vernier control?

The control method sets how precisely and how smoothly the heater delivers power. A contactor is a mechanical on/off switch — simplest and lowest cost, right for loads that tolerate temperature swing and don't cycle often; the contactor is a wear item. An SCR power controller is a solid-state device that proportions power continuously with zero-cross SCR for heating loads — tight temperature control, no moving parts, and the choice for precise or fast processes; Indeeco SCR controllers run to 50–70 A per unit, single- or three-phase, with master/slave for larger loads. A step controller / sequencer (S5, S10) switches a large heater in stages, so a big bank doesn't slam the line all at once and the heat ramps smoothly. Vernier control is a hybrid: contactors carry the bulk stages and one SCR-trimmed stage gives fine resolution. Add a PID temperature loop with a thermocouple or RTD and an independent high-limit safety, and the panel is complete.

What is an infrared heater, and how is it used?

It's an electric radiant heater: a panel with a heated emitter face that radiates medium-wave infrared heat directly onto the product, rather than heating the air around it the way a convection heater does. Because the energy lands on the surface, processes such as drying, curing, laminating, thermoforming, and preheating run faster and more controllably — which is why these panels are typically integrated into OEM machinery and production lines rather than sold as standalone room heaters. Solar Products, the Aspeq Infrared Division and North America's largest custom IR-OEM heater manufacturer, builds them as made-to-order panels in the F, FBA, Q, T, M, G, and V series, sized to the wattage, wavelength, footprint, and mounting your application needs. Send us the target material, process temperature, line speed, and area, and we'll specify it.

Heat trace or impedance pipe heating — when do I use each?

Both keep a pipe warm; they do it differently. Heat trace is a heating cable run along the outside of the pipe under the insulation — self-regulating or mineral-insulated cable. It's the standard, flexible answer for freeze protection and process maintenance on ordinary runs, retrofits easily, and self-regulating cable adjusts its own output along its length. Its limits: it's an external add-on with a finite service life that eventually needs replacement and re-insulation. Impedance heating makes the pipe itself the heating element — low-voltage touch-safe current (under 30 V, NEC Article 427) is passed through the pipe wall, so the entire pipe heats uniformly with no hot spots. It suits very long runs, high-temperature service (to ~1600 °F), temperature-sensitive media where hot spots are unacceptable (chocolate, asphalt, heavy syrups), and critical lines that can never be taken down for re-tracing — many impedance systems run for decades unattended. The iHeat HRSG steam-drum sample-line system is a flagship impedance application, using far less power than tracing the same line.

Process-air heaters — what's the difference between open-coil, finned-tubular, and tubular elements?

All three heat a forced-air stream; they trade off response, watt density, and tolerance for dirty air. Open-coil elements are bare nichrome ribbon on ceramic insulators — the highest watt density, fastest response, and lowest pressure drop (exit air to ~1200 °F), but they need clean air only. Finned-tubular elements are sheathed tubular elements with crimped fins for more surface area — they tolerate some moisture and particulate and suit moderate exit temperatures (to ~600 °F) at high velocity. Tubular (no fins) elements are the most robust against fouling and mechanical abuse — the choice for dirty, particulate-laden, or chemically aggressive air, with exit air to ~1200 °F. Clean air and need fast response → open-coil; dirty or aggressive air → tubular; a balance → finned-tubular.

Are these custom-built, and what's the lead time?

Yes — industrial electric heating is a build-to-order business. Across all five brands (Indeeco, Heatrex, Accutherm, Solar Products, Hi-Heat) virtually every product is engineered to the application — the kW, watt density, sheath material, flange and enclosure rating, vessel, and control panel are all specified per job. There is no published price list, and pricing is quote-only. Lead times typically run about 3 to 14 weeks depending on brand and configuration. Because the heater is engineered, the more complete the process data you provide up front — fluid, flow or volume, temperatures, pressure, area classification, voltage — the faster and tighter the quote.

How do I replace or retrofit a heater that has failed?

A replacement has to match the application, not just the old part number. The specifications to capture from the failed unit and its vessel: the kW and voltage, the mounting (flange size and rating, or NPT thread), the sheath material and diameter, the immersed/heated length, the watt density, the terminal enclosure type and any hazardous-area rating, and the control scheme. Often the right move is to also ask why it failed — a heater that burned out from too-high watt density or mis-specified heater to application should be re-specified, not merely duplicated. Send us the nameplate, a photo of the installation, and the failure symptom, and we'll spec a replacement that is built to last longer in similar conditions.

Why do electric heating elements fail, and how long do they last?

Kept within their design conditions, industrial heating elements last many years. The common failure causes are nearly all about heat that couldn't get away from the element fast enough: dry-firing or low fluid level (an immersion element energized without full coverage overheats in seconds), watt density too high for the fluid (see watt density, above — coking, scaling, hot spots), fouling and scale that insulate the sheath so heat builds inside, moisture ingress into the element causing a ground fault, and contamination or chemical attack on the sheath. Most are preventable with a proper watt-density spec, the right sheath, a low-level cutoff, and a high-limit safety. An element that keeps failing is telling you the original specification was wrong.

Is electric heating efficient, and how does it compare to gas?

At the point of use, electric heating is essentially 100% efficient — there's no flame, no flue, and no combustion gases carrying energy up a stack, so practically all the electrical input ends up in the process. A fuel-fired heater loses a meaningful fraction to flue gas. That said, the operating cost comparison depends on local electricity versus fuel prices, and on the application. Where electric heating clearly wins is precise control, fast response, zero on-site emissions, no combustion-air or flue infrastructure, placement in spaces where a flame isn't allowed, and low maintenance. For process heating that needs tight temperature control or sits in a classified or enclosed area, electric is often the practical choice regardless of the raw energy-price math.

What is a flexible heater, and where is it used?

A flexible heater is a thin, conformable heating element built onto a bendable substrate so it can wrap or adhere to a surface that isn't flat. Hi-Heat builds them in three substrates: silicone rubber — rugged, tolerates moisture and rough handling, service to about 200 °C; polyimide (Kapton®) — the thinnest format, with aerospace-grade thermal stability and low outgassing for vacuum and cleanroom use; and polyester film — a cost-effective option for low-temperature OEM work. The resistance element inside is either wire-wound (highest watt density) or etched-foil (very uniform heat, tight resistance tolerance). They're used wherever the heater has to follow the shape of the part — freeze protection on tanks and pipes, medical and lab instruments, aerospace components, and OEM equipment — and are sized and shaped to your drawing.

Who invented electric resistance heating?

The physics was established by James Prescott Joule in the 1840s: Joule's law showed that the heat a conductor gives off is proportional to its resistance and to the square of the current through it — which is why resistance heating is still called "Joule heating." Turning that into a durable industrial device took the early 20th century, when nichrome resistance alloy (which holds up at high temperature without oxidizing away) and the magnesium-oxide-insulated, metal-sheathed tubular element were developed. That sheathed-element construction is still the basis of the immersion, circulation, and duct heaters in use today.

Need a custom heater spec? Talk to Scott — sent directly to Scott Prater at scott@pratertechnical.com, or call him directly at 917-580-0878 during business hours.

From the field: Prater Technical Partners regularly consults on and recommends custom-engineered heaters & controls from customer process data and environmental conditions, including hazardous-area. Specialty systems include impedance-based pipeline and HRSG steam-drum sample-line heating, Sure-Steam wet-pack-prevention superheaters for medical and pharmaceutical autoclave loops, and Accutherm Mil-Spec and Marine-Duty builds. For process, freeze-protection, lab, pilot-plant, and OEM uses, we partner with you to narrow choices and fine-tune specifications — carrying each defined spec through factory quotation, order processing, engineered-drawing approval, and shipment status.

— Scott Prater, Principal, Prater Technical Partners
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