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How to Install Trench Heaters

How to Install Trench Heaters

Architects, builders and engineers are always looking to push the envelope in their commercial building designs. These unique designs capture imaginations and inspire people who use the building each day without compromising the building’s functionality. With large open gathering spaces, high-performance glass facades and ever-changing office spaces, construction and design professionals are finding new essential building system technologies to serve their unique designs better.

Recently gaining more popularity among the architectural design community, trench heaters have evolved to be an efficient, customizable, and low-cost solution to traditional HVAC systems or finned tube radiators. Trench heaters offer many benefits to a commercial building and are easily installed with endless customization options, keeping installation minimally invasive and on-time.

How Trench Heaters Work

Trench heater units are the key components to a perimeter heating system. At AirFixture, we offer hydronic (water) and electric trench heaters. Both trench heaters are effective in throwing heated air to create a perimeter of insulation, maintaining consistent temperatures throughout a space. While both hydronic and electric trench heaters accomplish the same goal, each serve a unique purpose in a commercial space. By installing trench heating as a primary or secondary heat source in a commercial building, large spaces will experience fewer downdrafts, cold spots, and other temperature inconsistencies.

Hydronic Trench Heaters

Soho Hydronic Fan Terminal units can work with hot water boilers, natural ground heat sources, and solar-heated water systems. The hydronic system easily connects to the main water source line using 1/2" Male NPT supply and return connections. Air is brought into the system from 24VDC variable speed ECM cross-flow fans to recirculate air in the room. The air is heated by the hydronic heating fin pack, and the cross-flow fans throw the heated air back into the room. Our hydronic units do require a SoHo Hub (up to 16 units per 1 Hub) to provide power and control.

Electric Trench Heaters

Similar to our hydronic trench heaters, our Electric trench heaters use 24VDC variable speed ECM cross-flow fans to bring air into the system, recirculating air from the room. The air is then heated by the 0.5-2.0kW sheathed-type electric heating element and thrown back into the room through the fitted steel grilles, flush with the floor.


While SoHo hydronic and electric trench heaters work differently, they bring the same short and long-term benefits to commercial properties.

  • Occupant comfort: Trench heating consistently recirculates heated air into a room, creating a blanket of insulation that helps the room’s air distribution system stay consistent and minimize hot or cold spots. It makes condensation a non-issue and is a perfect choice for floor-to-ceiling windows, which adds to the appeal of the construction and design.
  • Improved air quality: Unlike overhead heated air distribution systems, trench heaters operate at lower velocities and do not blow air with such great force directly into the breathing zone. They let gravity raise the heated air naturally, reducing pollutants and allergens in the air.
  • Reduced noise pollution: Trench heating systems are noticeably quiet compared to larger overhead fans or finned tube radiators.
  • Long-term energy savings: Trench heating is an efficient way to heat a building as the heat is distributed evenly along the perimeter space. This can lead to significant savings on energy costs over time. Hydronic trench heaters also take advantage of ground source heat pumps, allowing for better use of utility-provided water. According to a 2022 JLL report, buildings with considerable retrofits on MEP equipment experience 30% - 40% energy savings and logistics centers with similar retrofits experience 20% - 25% energy savings year over year.
  • Reduced maintenance costs: Trench heating systems require minimal maintenance. To clean the units, crews simply remove the grille, dust and clean as needed, and replace the grilles. This means that there is less wear and tear on the system, which can lead to longer lifespans. It also lowers the amount of maintenance touchpoints that interrupt tenants’ leased areas.
  • Increased property value: Trench heating can increase the value of a property, as it is a desirable feature for many buyers. Plus, it maximizes the most available floor space making use of the square footage.

These benefits can greatly impact the profitability of commercial spaces while keeping in-unit tenants happy with their air quality and overall comfort. However, as commercial real estate continues to evolve, custom perimeter heating solutions will develop to fit specific needs. Trench heaters are the preferred solution for specific properties. This graphic explains in a side-by-side comparison.

3389 - How to Install Trench Heaters_Table Graphic

What kinds of properties are right for trench heating?

Properties with Raised Access Flooring

Trench heaters can be easily and quickly installed under an existing raised floor system. With nearly no additional construction or installation time required, trench heating units can be added at any time under a raised floor to enhance the space’s perimeter heating.

Large Glass Walling

Large-scale glass facades have become the standard for commercial real estate buildings. Even the most advanced glass work will still be susceptible to allowing heat gain and loss. Trench heaters help to maintain glass temperature, insulating the interior of the building.

Lobbies or Atriums

Spacious lobbies and atriums have an increased opportunity for down drafting and hot and cold spots as there are fewer room dividers to break up the space. Trench heaters help to minimize those temperature issues while keeping the fan noise level low and allowing for usable floor space all the way to the walls.


Trench heaters help to maintain consistent temperatures in vestibules that are constantly exposed to outdoor temperature swings. The low-profile trench heaters also maximize the floor space in vestibules as the grille covers can be walked on.

Open Floor Plans

As designers continue to create more collaborative corporate office spaces with fewer walls and separated zones, the spaces can suffer from temperature inconsistencies. Installing trench heaters and other air distribution systems like underfloor air diffusers can increase occupant comfort.

In addition to new construction commercial projects, existing buildings can benefit from converting to trench heating  . From adding trench heaters under existing raised floor spaces to quickly and easily digging a perimeter trench to add insulation to your building, trench heater conversation can Improve an existing building’s energy usage and raise its resale value.

Customize your Trench Heater with AirFixture

Traditional heating units come in specific shapes and sizes, leaving little room for customization. At AirFixture we recognize that every commercial real estate project is unique. Because we know this, nearly every aspect of our SoHo Trench Heaters is customizable to fit in any project.

Our engineering team works directly with project architects and engineers to seamlessly include our trench heaters into their 2D and 3D building plans. As utility access points are laid out, our team will customize our trench heating units to maximize accessibility and minimize the impact on the existing design and engineered essential building systems.

Hydronic vs. Electric

Our two different styles of trench heating, hydronic and electric, are designed to work seamlessly with an existing building or a working building plan. Based on the requirements of the project and location of accessible water and power connections, our AirFixture engineering team works directly with project architects and engineers to recommend and implement either of our SoHo trench heating systems.

Physical Trench Heater Sizing

Because we design and manufacture our trench heating systems, we can create them to fit unique architectural designs. Our in-house manufacturing team can custom create trench heaters to fit along curved walls, in sharp corners, and between non-standard spaced mullians, the vertical bars between panes of glass windows, all while allowing for easy access points and efficient airflow.

Custom Grilles

When you are choosing a trench heating solution, it is important that the systems fit the design aesthetic of the space. We manufacture our grilles in-house, allowing us to custom-create grilles and top grates to fit any specification. From sharp angles and curved walls to unique coloring and variable overhang sizing, we can design grilles to seamlessly fit the design of the commercial space.

Once architects and building developers have decided to invest in trench heating, they can begin to prepare for trench heater installation.

Laying the Groundwork for Trench Heater Installation

At AirFixture, we work with project architects and engineers from day one to develop detailed drawings and building plans to incorporate our trench heating units and any underfloor air distribution systems. In new construction buildings, our products are included in the design to allow architects to freely design without additional consideration for essential building heating systems.

Our trench heaters require a 5-inch deep and 8-inch-wide trench along the inside of the perimeter of the building to be installed. The trench heaters can be manufactured to fit into different shapes, matching the contour of the wall.

Our SoHo trench heating units are designed for flexible configurations. We can design custom units to be installed on the walls or the ceiling of a space. For SoHo trench heating units planned for installation recessed in the walls or ceiling, the same 5x8-inch trenches are required. For trench heaters installed on the exterior of the wall or hung from the ceiling, no additional trenching is required as the unit will simply attach to brackets on the wall or ceiling. AirFixture features a variety of installation options.

Once the groundwork has been laid, trench heaters are installed in just a few simple steps.

Installing Trench Heaters

SoHo Trench Heater installation is quick and easy for general contractors. Our in-house manufactured products are delivered with just a few connection ports for installation.

  1. Area preparation: If installed into a raised flooring system, the installer will trim the adjacent floor tiles and reinstall them to fit around the SoHo trench opening. If installed into a dugout trench, the area will already be prepared to fit the trench heating unit.
  2. Unit Preparation: Once the unit has been prepared, it will simply sit in the trench. The installer levels the unit by lowering it until the outer flanges sit on top of the surrounding floor. If installing a flangeless unit, the installer will level the unit using adjustable leveling legs to match the surrounding floor height. Once the unit is leveled, it will be taken back out for the next steps.
  3. Establish connections: The unit is connected to all power and water sources in compliance with local codes and regulations.
  4. Connecting Thermostats: Internal and external thermostats are installed and connected using Plug & Play Cable. These thermostats give detailed temperature measurements to the users so they can adjust the trench heating at any time.
  5. Verify power connections: Using a voltmeter, the installer will check SoHo power lugs to verify power signal. They will set the thermostat 10°F above room temperature and verify that the fan and heater are receiving power and working properly.
  6. Place the unit into the trench, being sure to double check the unit leveling.
  7. Install the linear grille directly on top of the heating unit.

The vast majority of trench heaters are installed in the flooring, but our custom options are just as easy to install. For ceiling and wall recessed and hanging installation, the process is almost identical. The only difference for installation is that our manufacturing team will need to discuss installation plans with the general contractor.

How much do Trench Heaters cost?

While trench heating brings an additional upfront cost to a commercial project, the systems can drastically reduce ongoing energy costs associated with heating and cooling and outlast traditional furnaces and heating elements with minimal maintenance.

To learn more about our custom pricing, contact us today for an estimate.

Trench heaters provide impressive short-term and long-term benefits to commercial buildings. From lowered energy costs to easy installation and maintenance, AirFixture’s SoHo trench heating units allow building developers and architects to focus on a larger design and business plan while having a reliable, low-profile heating solution. If you are interested in learning more about how trench heating can benefit your commercial real estate project, contact us today.

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