Key Takeaways
- Purpose-Built for Docked Trailers: Unlike standard warehouse heaters, Reznor DTH units deliver warm air directly into the trailer interior—achieving up to a 21–22°F temperature rise in just seven minutes and keeping workers comfortable during winter operations.
- Efficient, Electric, and Safe Operation: The DTH’s 100% electric design eliminates combustion, exhaust, and carbon monoxide risk while meeting UL and CSA safety standards—offering clean, maintenance-free performance in high-traffic dock environments.
- Proven ROI for Facility Managers: Field data shows measurable productivity gains and lower operational costs, with average savings of $2,000+ per worker per year—making Reznor DTH heaters the most cost-effective dock heating solution on the market.
Article Contents
Winter can make warehouse and loading dock work a real challenge. Cold trailers slow down loading and unloading, and it’s tough to keep your team motivated when the temperature drops. This can lead to lower productivity and more safety concerns. The Reznor DTH Unit Heater is designed to address these issues. In fact, it can warm up docked trailers in just seven minutes, as proven by real installations in the Northeast.
Our Reznor Docked Trailer Unit Heater (DTH) buying guide explains how these heaters work, their pros and cons, and how they compare to other options.
What Are Docked Trailer Heaters?
The Reznor DTH (Docked Trailer Heater) is the first heater designed specifically for docked trailers. Unlike general warehouse heaters that waste energy warming massive spaces, the DTH mounts directly above your dock door and delivers heat inside the trailer where workers need it.
How Does the Reznor DTH Electric Heater Work
The idea behind the DTH is simple: target the trailer interior instead of wasting heat across your entire dock. High-velocity fans push heated air through a flexible canvas nozzle into the top of your trailer. This powerful stream of heated air is delivered directly into the trailer, ensuring efficient warming and improved comfort. This creates a circulation pattern that works beautifully. Warm air enters at the top while cold air exits at the bottom. Within minutes, the cold air inside the trailer is warmed to a comfortable temperature thanks to premium heating elements that deliver fast, efficient heating.
The flexible canvas nozzle is a big plus for dock safety. If a forklift bumps into it, the canvas just absorbs the impact, resulting in no damage, no repairs, and no safety hazards from broken parts. Your team can keep working without interruptions.
Installation is simple, thanks to the included mounting kit. You don’t have to worry about overheating, either. The heater has automatic safety controls that shut it down if airflow stops or if it gets too hot, and it resets itself when things return to normal.
Reznor Docked Trailer Unit Heater Pros and Cons
Pros of Reznor DTH Electric Heaters
- 7-minute warm-up time: Field tests show you can get a 21.6°F temperature boost in just minutes. Even if your dock is at 63°F, the trailer can reach a comfortable 74°F fast. No more waiting around for things to warm up
- Measurable ROI: On average, you could see productivity gains worth $2,026 per employee per year, with potential network savings reaching $4.1 million for large operations
- Boost worker morale and safety by 72%: Based on actual pilot program data from northeastern installations
- Year-round functionality: The fan-only mode gives you ventilation in the summer, which is great when trailers get hot - it’s easy to use and helps keep your trailers comfortable year-round
- Dual-zone heating benefit: As warm air leaves the trailer, it also helps heat your dock area - this can take some of the load off your main HVAC system and make your whole dock more comfortable
- OSHA compliance support: These heaters help reduce cold exposure, so your team won’t need bulky winter gear - they also help prevent ice and cut down on delays caused by cold weather.
- Minimal maintenance: No filters to change, no combustion parts, and no exhaust systems to worry about
- Forklift-resistant design: he flexible chute absorbs bumps from forklifts, so you don’t have to worry about damage
- Pre-assembled delivery: The unit arrives ready to go on a crate that doubles as a lift, making installation easier
Cons of Reznor DTH Unit Heaters
- Higher upfront cost: These heaters cost more at first than portable or infrared options
- 3-phase power required: You’ll need 208V, 240V, 480V, or 600V three-phase electrical service for any model
- Professional installation necessary: Not a DIY project
- Fixed installation: Once installed, the unit cannot be moved between docks
Reznor Docked Trailer Heater (DTH) Features
Durable Construction for Busy Loading Docks
Your loading dock equipment takes abuse, and the DTH is built to handle it:
- The galvanized steel cabinet is resistant to rust and weather damage
- Painted finish with scratch-resistant coating
- Impact-resistant flexible nozzle resists damage from forklift impact
- Mounting rails and hardware are provided for installation
Safe, Low-Maintenance Electric Operation
Safety certifications and features protect your workers and facility:
- UL 2021 and CSA C22.2 #46 certified for US and Canada
- Resets itself if it overheats
- Won't heat up unless the fan is running
- OSHA-compliant fan guards with overload protection
- Quiet motor design
- All-electric means no CO risks or venting needed
Other Features to Consider
- Simple controls: Wall-mounted panel with three push buttons (heat/fan/off)
- Multiple voltage options: Compatible with 208/3, 240/3, 480/3, 600/3 electrical systems
- Clearance requirements: 36" top, 21" sides, 1" front (discharge side)
- Optional accessories: Disconnect switches, door sensors, smart controls for BMS integration
- 5-year warranty: Comprehensive coverage on electrical and mechanical components
How to Choose the Right Docked Trailer Heater to Make Cold Trailers Warm
Choosing the Right kW Output for Your Trailer Size
Choose the DTH-18 if your facility:
- Uses standard 53-foot trailers
- Requires reliable heating for moderate climates
- Needs a 35–45°F temperature rise with 13–18 kW output
- Size of dock needs airflow with a 1200 CFM rating
Choose the DTH-30 if your facility:
- Operates in extreme cold regions
- Handles refrigerated trailers starting at lower temperatures
- Needs maximum heating speed for high-turnover docks
- Services oversized trailers requiring 1850 CFM airflow
| Reznor DTH Docked Trailer Unit Heater Product Comparison | |||
|---|---|---|---|
| Feature | DTH-18 (208/240 V) | DTH-18 (480 V) | DTH-30 (480 V) |
| Primary Application | Purpose-built to heat interiors of docked trailers; mounts above dock door | Purpose-built to heat interiors of docked trailers; mounts above dock door | Same trailer-interior focus but for larger/heavier applications |
| Heating Method | High-velocity electric forced-air through flexible nozzle | ||
| Warm-Up Time | 7 minutes | ||
| Energy Source | Electric, 3-phase (208/240 V) | Electric, 3-phase (480 V) | Electric, 3-phase (480 V) |
| Installation | Pre-assembled; mounts above dock door; minimal clearance required | ||
| Controls | Wall switch (Heat / Fan / Off) with safety interlocks | ||
| Year-Round Use | Yes — fan-only mode for summer ventilation | ||
| Construction | Galvanized-steel cabinet, flexible canvas nozzle, low-noise fan | ||
| Safety Features | High-limit switch, airflow proofing, thermal overload protection | ||
| Noise Level | < 65 dBA | ||
| Maintenance | Minimal — periodic electrical inspection | ||
| Best Application | Docked trailers and cold-climate docks needing rapid, uniform heat (standard trailer size) | Same as DTH-18 (208/240 V) but suited to facilities with 480 V infrastructure | Oversized trailers, high-turnover docks, or extreme-cold operations requiring 30 kW / ~102,000 BTU |
Think about your climate zone before choosing. If you’re in the North, you might want to use DTH-30 units everywhere. In milder areas, DTH-18 models can save you money. You can also mix and match - use bigger units for exposed docks and smaller ones for sheltered bays.
Optimal Mounting Height and Nozzle Placement
Mount the unit directly above the dock door, centered for even heat distribution. Angle the flexible nozzle slightly downward into the trailer. This setup gives you the best air flow and keeps the heater out of the way during daily work.
The pre-assembled crate can be used as a lift during installation, but it’s best to have a professional handle the setup to make sure you get:
- Correct electrical connections for your voltage configuration
- Best nozzle positioning for your trailer heights
- Compliance with local codes and safety requirements
- Proper integration with existing dock equipment
Fan Mode vs. Heat Mode: Which to Use and When
Heat Mode: Use during cold weather (typically November through March in most regions). Start heating when trailers dock and continue throughout loading/unloading operations.
Fan Mode: Deploy during summer for ventilation and cooling. Especially valuable when trailer temperatures exceed 100°F. Also useful in spring/fall for air circulation without heating costs.
Switching between modes is easy with the single-button control. It’s a good idea to train your team on when to use each mode. Many facilities use simple rules, like fan mode above 60°F and heat mode below 40°F, and adjust as needed.
How the Reznor DTH Unit Heaters Compare to Other Heating Systems
Reznor Infrared Tube Heater
Reznor UDXC Gas-Fired Unit Heater
LB White Tradesman Portable Forced Air Heater
Re-Verber-Ray DR Series Infrared Heater
Many warehouses still use portable propane heaters, infrared systems, or standard unit heaters for their docks, but these aren’t designed for heating docked trailers. The Reznor DTH Unit Heater is different. It’s designed to send heat right into the trailer, so you’re not wasting energy on the whole dock. This makes loading and unloading in cold weather much easier and safer. Here’s how the DTH compares to other common dock heating systems, and why it’s a smart choice if you need fast, reliable trailer heating.
| Loading Dock Heating Options Comparison Table | ||||
|---|---|---|---|---|
| Feature | Reznor DTH Docked Trailer Heater | Infrared Tube Heater (Gas or Electric) | Electric Forced-Air Heater | Fuel-Fired Portable Heater (“Torpedo”) |
| Primary Application | Purpose-built to heat interiors of docked trailers; mounts above dock door | Radiant heat for open bays and loading zones | General space heat for enclosed docks or shops | Temporary or outdoor spot heat |
| Heating Method | High-velocity electric forced air through flexible nozzle | Infrared radiation; no air movement | Fan-forced electric resistance | Combustion-based forced air (diesel, propane, kerosene) |
| Warm-Up Time | 7 min | 20–30 min | 10–20 min | 15–20 min + significantly longer in enclosed trailers |
| Energy Source | Electric, 3-phase | Gas, propane, or electric | Electric, single / 3-phase | Fuel-burning (diesel, propane, kerosene) |
| Installation | Pre-assembled; mounts above dock door; minimal clearance | Suspended tubes; venting required | Thermostat or switch | Manual or on-unit thermostat |
| Controls | Wall switch (Heat / Fan / Off) with safety interlocks | Thermostat / zone control | Winter only | Winter only |
| Year-Round Use | Yes – fan-only mode for summer ventilation | Winter only | Winter only | Winter only; recommended to use outdoors |
| Construction | Galvanized-steel cabinet, flexible canvas nozzle, low-noise fan | Steel tubes + reflectors | Steel cabinet + louvers | Steel housing + fuel tank |
| Safety Features | High-limit switch, airflow proofing, thermal overload protection | Flame-failure valves, clearance rules | Thermal cutoff, fan delay | Flame sensor, requires ventilation |
| Noise Level | < 65 dBA | Quiet (no fan) | 60–70 dBA | 10–90 dBA |
| Maintenance | Minimal – periodic electrical inspection | Occasional cleaning | Basic fan / electrical check | Frequent burner / fuel maintenance |
| Best Application | Docked trailers and cold-climate docks needing rapid, uniform heat | Ambient heat for open warehouse, dock, and outdoor spaces | Enclosed warehouse areas | Temporary outdoor / construction use; not safe or effective in enclosed areas |
The information in this comparison table is general and simplified for reference purposes. Specifications, performance data, and features may vary by manufacturer, brand, and individual model. Always verify details with the official product documentation or manufacturer before making installation or purchasing decisions.
Sources:
- Reznor DTH Docked Trailer Heater Brochure
- Reznor Electric Products Brochure
- Roberts-Gordon DTH Dock Heater Product Page
- Roberts-Gordon Infrared Tube Heater Overview
- ASHRAE HVAC Applications Handbook (2023) – Chapter 5 “Industrial and Dock Heating.”
Purpose-Built for Docked Trailers, Not General Warehouse Heating
Standard warehouse heaters warm up the whole space, but trailers can still stay cold. The DTH is different, sending heat right into the trailer through its flexible canvas nozzle, so you’re not wasting energy and your team stays comfortable where it matters most.
Faster Warm-Up Times Than Infrared or Portable Heaters
Based on field testing and manufacturer specifications:
- DTH heaters: 7 minutes to comfortable temperatures
- Portable propane heaters: 15-20 minutes, plus safety hazards
- Infrared heaters: 20-30 minutes to heat the opening of the trailer, it would not heat the inside since it only warms objects that are in its direct path
- Standard unit heaters: 25-30+ minutes if trailer warms at all
The DTH’s forced-air system evenly heats the entire trailer. You won’t have cold spots behind pallets or temperature changes as your team moves around.
Energy Efficiency and Airflow Advantages of Electric Heating
Since the DTH is fully electric, all the power goes straight into heating—no energy is lost to combustion or exhaust like with gas systems. You get clean, consistent heat right where you need it. The strong airflow thoroughly mixes the air, so you don’t get hot air trapped at the ceiling.
As warm air leaves the trailer, it also helps heat your dock area. This can help lower your main warehouse heating costs, especially if you need to keep different areas at different temperatures.
Available Models at HVACDirect.com
HVACDirect.com stocks three DTH configurations, 2 DTH-18 and 1 DTH-30, to match your electrical infrastructure:
Reznor DTH-18 Models:
- Reznor DTH-18 Docked Trailer Electric Unit Heater - 17.7kW / 62,000 BTU, 208V-240V 3 Phase
- Reznor DTH-18 Docked Trailer Electric Unit Heater - 18kW / 62,000 BTU, 480V 3 Phase
Reznor DTH-30 Model:
| Reznor DTH Models at HVACDirect.com | ||||||
|---|---|---|---|---|---|---|
| Model | Kilowattage | Voltage | BTU Output | Discharge Air Temperature Rise | Air Volume (CFM) | Best Application |
| DTH-18 | 13–18 kW | 208–240 V | 44,000–60,000 BTU | 35°F–45°F | 1200 | Standard 53’ trailers, moderate climates |
| DTH-18 | 18 kW | 480 V | 62,000 BTU | 45°F | 1200 | Standard 53’ trailers, moderate climates |
| DTH-30 | 30 kW | 480 V | 102,000 BTU | 50°F | 1850 | Large trailers, extreme cold conditions |
All models ship directly from HVACDirect.com to ensure safe delivery. We guarantees your unit will arrive undamaged and ready for installation.
Reznor DTH Unit Heaters Frequently Asked Questions
DTH stands for Docked Trailer Heater. This as a purpose-built unit heater is specifically made for loading dock applications.
Yes. The targeted heating approach warms only the trailer space, not the entire warehouse. The dual-zone heating effect (trailer plus dock area) and electric efficiency maximize energy value. Field tests show reduced overall facility heating costs.
No venting is required. These are electric heaters with no combustion, no exhaust, and no carbon monoxide risks. This simplifies installation and eliminates heat loss through exhaust systems.
You can get electric trailer heaters at low, wholesale prices from HVACDirect.com. Our team can help you pick the right model and connect you with qualified installers near you.
Studies show that 72% of workers are still unhappy with traditional dock heating methods. That’s a clear sign it’s time for a better solution, like the Reznor DTH.
Shop Reznor DTH Unit Heaters at HVACDirect.com
Adding a trailer heater, such as a Reznor DTH, is a smart way to keep your operations running smoothly year-round. With average returns of $2,026 per worker each year, most businesses see payback in just a few months. You’ll also see fewer injuries, happier employees, and less turnover. Not sure where to start? Our team can help you choose the best heater to make your dock more efficient.
Don’t let winter slow down your dock. Contact HVACDirect.com today to upgrade your cold-weather operations with Reznor DTH docked trailer heaters. Your workers, and your bottom line, will thank you.
