Explosion-Proof Duct and Unit Heaters
Specifying an explosion-proof duct heater for make-up air into a classified building, or an explosion-proof unit heater for a refinery pump house, chemical plant or wastewater lift station? We handle both.
We supply Indeeco explosion-proof heaters matched to your class, division, gas group, T-code, kW and voltage.
We size it, quote it, and return a selection ready for submittal. Our offices are in Houston and Dallas-Fort Worth, serving Texas and the Gulf Coast, and we ship nationwide.
Not sure which explosion-proof heater fits your area?
We match the model to your hazardous location.
Key Takeaways
Indeeco Explosion-Proof Heater Models
We supply five Indeeco explosion-proof heaters: three duct heaters that mount in the ductwork and two unit heaters with their own fan.
| Model | Type | Hazardous rating | Range | Construction |
|---|---|---|---|---|
| Ultra-Safe duct heater | Duct heater | Class I, Div 1 and 2, Groups B, C, D. Class II, Div 1 and 2, Groups E, F, G. T3C, 320°F (160°C). FM and CSA approved | Up to 240 kW, 600 V. Ducts 12 x 12 in to 75 x 35 in | Standard, corrosion resistant, outdoor or wet location |
| Series EP2 | Duct heater | Class I, Div 2, Groups C, D. T3, 392°F (200°C). FM and CSA approved | Up to 1,000 kW, 600 V. Ducts up to 240 x 120 in | Outdoor or wet location. Approved for shipboard use |
| Custom explosion-proof duct heater | Duct heater | Class I, Div 1 and 2, Groups C, D. Class II, Div 1 and 2, Groups E, F, G. T1 to T3B. Not FM or CSA approved | Up to 750 kW, 600 V. Ducts smaller than 12 x 12 in, vertical airflow | Slip-in or flanged, outdoor or wet location |
| Ultra-Safe EXP | Unit heater | Class I, Div 1 and 2, Groups C, D. Class II, Div 1 and 2, Groups F, G (Group E optional). T3C, 320°F (160°C). cCSAus | 3 to 35 kW | Standard, 316 stainless steel for wastewater, Dirty Duty Heresite coated for chemical plants, IP55 wet location |
| Compact | Unit heater | Class I, Div 1, Group D. Div 2 when wired and sealed to Div 1 rules. CSA | 13 in wide, wall or ceiling bracket | Dirty Duty (NEMA 4X, 7, 9), marine duty ABS approved and USCG compliant |
Common Questions
Do I need a Division 1 or Division 2 explosion-proof heater?
An explosion-proof heater needs a Division 1 rating when the gas or dust is present in normal operation or during maintenance. Division 2 applies when the gas escapes only if a pipe, seal or vessel fails. Choose the gas group and T-code together. A Division 2, Group D area can use an EP2 duct heater up to 1,000 kW.
What does T3C mean on an explosion-proof heater?
T3C on an explosion-proof heater means the heater's hottest surface never exceeds 320°F (160°C). That temperature must sit below the ignition temperature of every gas or dust on site. Acetaldehyde ignites at 347°F (175°C), so an area with acetaldehyde needs a T3C heater, and a T3 heater rated 392°F (200°C) is not allowed.
Which explosion-proof heater works in a wastewater plant?
A wastewater plant with hydrogen sulfide needs an explosion-proof unit heater rated for Group C. Hydrogen sulfide is a Group C gas that ignites at 500°F (260°C). The Ultra-Safe EXP covers Groups C and D at T3C, and Indeeco builds it in 316 stainless steel for wastewater. The Group D only Compact is not suitable there.
Explosion-Proof Duct Heater vs Unit Heater
An explosion-proof duct heater mounts in the ductwork and heats air that the building’s own fan moves. It suits make-up air and ventilation air going into a classified building.
An explosion-proof unit heater has its own fan and hangs on a wall or ceiling, so it heats a room directly, such as a pump house or lift station. Choose the duct heater when the space already has ducted air, and the unit heater when it does not.
| Explosion-proof duct heater | Explosion-proof unit heater | |
|---|---|---|
| Mounting | Flanged into the duct, horizontal airflow (custom units allow vertical) | Wall or ceiling bracket |
| Fan | Uses the air handler or supply fan | Built-in fan, 1/4 to 1/2 HP |
| Airflow | Set by the duct system | 650 to 3,850 CFM, air throw 15 to 75 ft |
| Range | Up to 1,000 kW | 3 to 35 kW |
| Indeeco models | Ultra-Safe, Series EP2, custom | Ultra-Safe EXP, Compact |
The duct heater depends on the system fan. On the Ultra-Safe duct heater, a fan relay keeps the heater off unless the fan is running. Size also decides the choice: one EP2 duct heater reaches 1,000 kW, while the largest Ultra-Safe EXP unit heater is 35 kW.
Related Heaters and Hazardous Location Equipment
- Explosion-proof heaters – Electric heat for classified hazardous locations
- Explosion-proof screw plug immersion heaters – Heating for tanks and process liquids in hazardous areas
- Electric duct heaters – Standard and custom duct heaters for HVAC and process air
- Marine duct heaters – ABS approved duct heat for shipboard use
- Unit heaters – Wall and ceiling heaters for general industrial and commercial spaces
- Explosion-proof fans – Ventilation fans for classified locations
- Explosion-proof actuators – Damper actuators for Class I and Class II areas
- Wastewater treatment ventilation – Ventilation equipment for lift stations and treatment plants