Electric heater batteries for ducts and air handling units
SPC Electric Heater Batteries heat the air in ducted ventilation systems and air handling units, using sheathed electric elements in place of a hot water or steam coil. Each electric heater battery is made to order for its duty, electrical supply and duct, for rectangular or circular ducts or to fit inside an air handling unit. SPC also supplies Controllable Electric Heater Batteries, which combine the heater, thyristor control and safety devices in one package.
Supplied by S & P Coil Products Limited (SPC), alongside SPC’s coil heat exchangers. Electric heater batteries are used in commercial, public, healthcare and industrial buildings wherever supply air needs heating, with duties from 0.5 kW up to 400 kW in a single section on single or three phase supplies.
Rectangular or circular
Duct mounted, or built to fit inside an AHU
Made to order
Duty, supply and stages to suit the project
Controllable range
Heater, thyristor control and safety devices in one package
Overheat protection
Overheat cut-outs on every heater battery
0.5 to 400 kW
Duty in a single section (Electric Heater Batteries), made to order for the airflow and duct.
1 or 3 phase
Single or three phase supplies. Controllable models: up to 8 kW single phase, 135 kW three phase.
0-10V control
Suitable for 0-10V thyristor control, built in on Controllable models with a BMS input.
BS7351
Electric Heater Batteries: 8 mm sheathed elements, designed for surface temperatures below 400°C.
What is an electric heater battery?
An electric heater battery is a set of electric heating elements in a casing that fits into ductwork or an air handling unit. Air passes over the elements and is warmed before it reaches the rooms the system serves. Electric heater batteries are also called electric duct heaters, duct heater batteries or electric air heaters.
SPC Electric Heater Batteries use 8 mm Incoloy sheathed elements, with the resistance wire electrically isolated from the outer sheath. These elements comply with BS7351 and are designed to operate with surface temperatures below 400°C. Elements made from resistance wire on ceramic formers are available by special request.
SPC circular electric heater battery for duct mounting
An electric heater battery should only heat while air is moving over it, so it is always controlled together with the fan. The control circuit includes an overheat cut-out, an airflow (flow proving) switch and a temperature control, and the fan runs on for a short time after the heater switches off to cool the elements. Controllable Electric Heater Batteries include these devices; standard Electric Heater Batteries are wired into a control panel supplied by others.
Read more in our article Reliable Heating for HVAC Systems: SPC Electric Heater Batteries, or see SPC’s full range of heating and cooling coils.
What electric heater batteries can SPC supply?
SPC electric heater batteries are made to suit each project rather than chosen from a list of standard sizes. The table shows what each range covers; send your airflow, duty, electrical supply and duct size for a selection.
| Feature | Electric Heater Batteries | Controllable Electric Heater Batteries |
|---|---|---|
| Duty | 0.5 kW to 400 kW in a single section | Up to 8 kW single phase; up to 135 kW three phase |
| Electrical supply | Single or three phase | Single or three phase |
| Duct and mounting | Rectangular or circular duct mounting, or designed to fit inside an air handling unit | Circular up to 630 mm diameter; rectangular sizes to suit, with 20 mm mez flanges |
| Elements | 8 mm Incoloy sheathed elements to BS7351, surface temperature below 400°C; ceramic former elements by special request | 8 mm sheathed elements in 321 stainless steel |
| Casing | Rectangular: fully welded steel with a grey powder coated finish. Circular: rolled galvanised sheet steel | Galvanised steel sheet |
| Stages and control | Single stage as standard, multiple stages available; suitable for 0-10V thyristor control. Controls supplied by others | Thyristor (solid state) switching for continuous control; 0-10V BMS interface; supply duct temperature sensor; volt-free enable/disable |
| Safety devices | Manual reset and/or auto reset overheat cut-out, wired into the control circuit by the installer | Manual reset overheat cut-outs, differential pressure flow proving switch, fan control with run-on |
| Options | IP rated electrical boxes by special request | Stab-in heaters, plain casing flanges, remote fault signalling, room sensor/controller, low flow sensors |
| Location | Internal installation; electrical box on one side, or on the circumference of circular units | Internal installation |
| Testing | 2000V flash test and 500V Megger test before delivery | Safety tested before delivery |
Supplied by S & P Coil Products Limited (SPC), Leicester, UK. Full details are in the coil heat exchanger brochure, the Controllable leaflet and the IOMs in Downloads.
Electric heater battery ranges, controls and installation
SPC Electric Heater Batteries are the heater only: the elements, casing and overheat cut-outs, built to the duty, supply and number of stages on the order.
- Rectangular heaters bolt to the duct through a plain flange; circular heaters have spigot connections.
- Single stage as standard, or multiple stages, which need not be equally rated.
- Suitable for staged control or a 0-10V thyristor controller, both supplied by others.
- The overheat cut-outs are wired into the control circuit, in line with the contactor coil, never into the heater power circuit.
Controllable Electric Heater Batteries combine power and control in one package, so there is no separate control circuit to buy. Thyristor switching modulates the output continuously to match the load, rather than only switching on and off or in stages.
- Local control: set the supply temperature with the push buttons and display on the front panel.
- BMS closed loop: the BMS sets the temperature through the 0-10V input. BMS open loop: the BMS sets the heat output directly.
- Room control: with the optional room sensor/controller fitted.
- Fan control: the fan runs only when heat is needed, or continuously for ventilation, with a built-in run-on.
- The display shows heater, power and error status, with error codes for element, overheat, airflow and sensor faults.
Circular Controllable Electric Heater Battery
Rectangular Controllable Electric Heater Battery
Electric heater batteries are installed by your M&E contractor and wired by a qualified electrician to current IET regulations, following the IOM for each range.
- Mount the heater with the overheat cut-out at the top of the duct, following the airflow arrow on the casing.
- Airflow must be even across the elements: leave straight duct either side of the heater before any bends, using transition pieces where needed.
- Inside an air handling unit, support the heater and blank off any free area so air cannot bypass it. Use a mixing screen where it sits directly after a fan outlet.
- Maintenance: isolate the heater and let the elements cool, then clean with a dry cloth, compressed air or a vacuum. Never use liquids.
- Clean upstream filters regularly: blocked filters reduce airflow and cause overheat trips.
Where are electric heater batteries used?
SPC electric heater batteries heat supply air in commercial, public, healthcare and industrial buildings. Typical uses include:
Ducted supply air
Heating fresh air in ducted ventilation systems before it reaches the rooms they serve.
Air handling units
Heater batteries designed to fit inside an AHU, with the free area blanked off so all the air passes over the elements.
Zone and room control
Controllable models with a duct sensor or room sensor to hold the temperature of a zone.
BMS controlled buildings
A 0-10V signal from the BMS sets the supply temperature or the heat output.
Without extra pipework
Air heating where there is no hot water or steam at the duct or AHU, or where a small duty or reheat does not justify running pipework to it.
Replacement heater batteries
New heater batteries made to suit existing ductwork and plant.
SPC electric heater batteries are installed in buildings across the UK, including hospitals. At Derriford Hospital’s Dartmoor Building in Plymouth, SPC supplied the electric heater batteries and a replacement heater battery at short notice to keep the installation on schedule.
Selection and design support for electric heater batteries
SPC sizes each heater battery for your project, with technical support through installation and commissioning.
Get a heater battery selection
Send the airflow, duty or temperature rise, electrical supply and duct size, and SPC will select the heater battery, its stages or its control.
SPC coil heat exchangers
Water, steam and refrigerant coils for the same ducts and air handling units, supplied alongside SPC's heater batteries.
Coil heat exchanger CPD
An Introduction to Coil Heat Exchangers, SPC's CIBSE approved CPD for building services professionals.
Technical support
Help with wiring, commissioning and fault finding from SPC's technical team, with an IOM for each range.
Discuss your electric heater battery project
Whether it is a new ventilation system, an air handling unit or a replacement heater battery in a commercial, public, healthcare or industrial building, call 0116 249 0044, email spc@spc-hvac.co.uk or use the form below.
Frequently Asked Questions
Yes. Electric heater battery, electric duct heater, duct heater battery and electric air heater are names for the same thing: electric elements in a casing that heat the air flowing through a duct or air handling unit. A heater battery with a hot water or steam coil instead of elements is a water or steam heating coil.
Choose Electric Heater Batteries when the heater will be wired into a control panel or BMS that provides the switching, staging and safety interlocks, or when you need a large duty (up to 400 kW in a single section). Choose Controllable Electric Heater Batteries when you want the heater, thyristor control, flow proving switch and fan control supplied as one package (up to 135 kW three phase). SPC can advise on either.
Yes. Electric Heater Batteries are suitable for 0-10V thyristor control, with the thyristor controller supplied by others. Controllable Electric Heater Batteries have a 0-10V BMS input built in: the BMS can set the supply temperature (closed loop) or the heat output directly (open loop), and a volt-free enable/disable is included. Remote fault signalling is available as an option.
At least one overheat cut-out, an airflow (flow proving) switch so the heater cannot run without air, and a temperature control for each stage, plus fan run-on to cool the elements after the heater switches off. Every SPC heater battery has overheat cut-outs; on Electric Heater Batteries they are wired into the control circuit by the installer, while Controllable models include the cut-outs, flow proving switch and fan control.
Yes. SPC Electric Heater Batteries can be designed to fit inside an air handling unit. The heater is supported so it cannot move, and any free area around it is blanked off so all the air passes over the elements.
Yes. Because each heater battery is made to order, SPC can make a replacement to suit the existing duct, duty and electrical supply. Send the details from the existing heater’s label and its dimensions. Read more in How Does HVAC Coil Replacement Work in Commercial Buildings?
SPC electric heater batteries are intended for internal installation. IP rated electrical boxes are available on Electric Heater Batteries by special request; Controllable models are not IP rated, so if one is fitted outside it must be protected from the weather.
Overheat trips are almost always caused by low airflow or the controls, not the heater itself: check the fan, the airflow switch and that the upstream filters are clean. A manual reset cut-out must be reset once the cause is fixed. Regular trips are a safety warning, so find the cause before returning the heater to service, and call SPC’s technical team on 0116 249 0044 if the fault persists.
