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Tank Heaters
Circulation Heaters
The heater lives outside the tank. Liquid is pumped through an insulated heater vessel and returned hot. Nothing goes into the tank at all.
What it is
A circulation heater is a flanged element bundle inside its own insulated pressure vessel, with an inlet and an outlet. A pump moves liquid from the tank, through the heater, and back to the tank. The heater is plumbing, not tank hardware.
Because the flow rate through the vessel is known and controlled, a circulation heater gives you the tightest outlet temperature control of any electric heating method, and it can be sized for very large duties without needing a giant nozzle on the tank.
When it is the right choice
- The tank absolutely cannot be modified or entered. Only piping connections are needed, and those can often go on existing ports.
- You need accurate temperature. Outlet control at a known flow rate is far tighter than heating a tank in bulk.
- The volume is large. Hundreds of kilowatts without oversizing a tank penetration.
- You want the elements serviceable without touching process liquid. Isolate, drain the loop, pull the bundle.
- You are heating in line, not in bulk. Feeding a process at temperature rather than holding a whole tank hot.
- The tank is lined, plastic, or under warranty. No penetration, no argument with the tank vendor.
The tradeoffs
You are adding a pump, piping, valves and a control loop, so the installed cost is higher than dropping a heater into the tank and the system has more parts that can fail. It also depends on flow: if the pump stops while the heater is energized, the liquid in the vessel overheats fast. Flow switches and over-temperature cutouts are not optional on this product, and we quote them as standard.
Specifications
| Specification | Range or option |
|---|---|
| Rating per unit | 3 kW to 500 kW and above |
| Vessel construction | Carbon steel or 316 stainless steel, insulated and jacketed |
| Element bundle | Flanged hairpin bundle, removable for service |
| Sheath materials | 316 stainless steel, Incoloy 800, carbon steel, titanium, Monel 400 |
| Connections | NPT or ANSI flanged inlet and outlet, sized to the flow |
| Voltage | 240 V, 480 V, 575 V, 600 V |
| Phase | Three phase, single phase on smaller units |
| Orientation | Horizontal or vertical, specify for the available footprint |
| Required protections | Flow switch, high-limit over-temperature cutout, sheath thermocouple |
| Control | Outlet RTD or thermocouple driving an SCR power controller or contactor panel |
| Options | Complete skid with pump, strainer, valves, gauges and control panel; outdoor rated enclosure; ASME code vessel |
Common questions
Can a circulation heater heat an entire tank, or only the flow going through it?
Both. If you circulate the tank contents through it continuously, it will bring the whole tank up — it just takes longer than an immersion heater of the same rating because you are limited by how fast the pump can turn the tank over. Size on total tank volume and target heat-up time, and check that the pump can circulate the tank several times within that window.
What happens if the pump fails while the heater is on?
The liquid trapped in the vessel overheats within seconds to minutes, depending on watt density. This is why a flow switch interlocked to the contactor and an independent high-limit cutout are mandatory, not optional. Any circulation heater we quote includes both.
Is a circulation heater better than an immersion heater?
Not better, different. An immersion heater is cheaper, simpler and has fewer failure points, and it is the right choice when you can put something in the tank. A circulation heater is the right choice when you cannot penetrate the tank, when you need tight outlet temperature, or when the duty is too large for a practical tank nozzle.
Can you supply the pump and controls as one package?
Yes. Complete skids with pump, strainer, isolation valves, pressure and temperature gauges, and a control panel are quoted as one assembly so there is a single point of responsibility for the loop.
Will it work with corrosive chemicals?
Yes, with the right sheath and vessel material. It is often the better answer for aggressive chemistry, because the heater is isolated in its own vessel and can be drained and serviced without working over an open acid tank. Send a bath analysis and we will specify the wetted materials.
Heat the tank without touching the tank
Send the fluid, the flow rate, the inlet and outlet temperatures, and the voltage available. We will size the heater and quote the loop.