PDWD Double Skin Ducted
The Polar Air PDWD Double Skin is a high ESP ducted hydronic fan coil for concealed ceiling installations where longer duct runs and higher pressure performance are required. It operates within an ESP range of 50–220 Pa, with 150 Pa (0.6 in.wg) recommended for balanced operation.
Its double skin casing with 25 mm (1”) NBR insulation forms an effective thermal barrier, reducing heat transfer through the panels and maintaining stable supply air temperatures. This design improves energy efficiency, particularly in tropical climates where external conditions create higher thermal loads.
Installation and servicing are easy with quick duct couplings, an insulated drain pan, and service-friendly access points. It is suited for commercial, healthcare and industrial applications, such as sports facilities, hospitals, factories and large data server centers, as well as shopping malls.
5 sizes available · 2-pipe or 4-pipe models · 3R, 3R+1, 4R, 4R+2 & 6R configurations
Advantages
Heating & Cooling
Capacities up to 37 kW provides powerful cooling in summer and reliable heating in winter, for year-round comfort.
Ideal for various applications, including commercial, healthcare and industrial buildings, including shopping malls, hospitals, wine cellars and factories.
Double Sandwich Design
Double skin casing with 25 mm (1”) NBR insulation forms a thermal barrier that limits heat gain and loss and keeps supply air closer to design values, especially in tropical or humid environments.
Compared to single skin FCUs, casing losses are reduced, improving efficiency in concealed ducted applications.
Multiple rows: 3R, 3R+1, 4R, 4R+2 · 6R
Multiple coil row configurations provide greater surface area for heat transfer, delivering higher efficiency and more cooling and heating capacity.
The added surface also improves latent capacity for better humidity control and more consistent comfort across varying load conditions.
ESP Conditions
Medium to high external static pressures from 50 - 200 Pa (0.2 - 0.8 in.wg), recommended 150 Pa (0.6 in.wg).
Suitable for projects with extended ducting or complex layouts, including shopping centers, factories, and transport hubs where airflow must be sustained.
Models
Available in 5 sizes with both 2- and 4-pipe options. Our 2-pipe system handles seasonal changeover easily.
The 4-pipe allows simultaneous cool/heat, useful in tropical climates where most areas need cooling but some zones (night shift, rainy season) might need heating.
Installation & Maintenance
Installation and servicing are easy with quick duct couplings and accessible service points.
Supplied ready to install, with internal steel drain pan, thick 25 mm (1”)
NBR insulation, manual air vent + water purge valve and G2 (MERV 4) filter.
Capacities
Metric
🍃 Airflow: 305 – 6125 m3/h
❄️ Cooling: 2.2 – 37.1 kW
☀️ Heating: 1.8 – 35.1 kW
🔊 Sound pressure: from 43 dBA*
Imperial
🍃 Airflow: 242 – 2564 CFM
❄️ Cooling: 9968 – 77691 BTU/Hr | 0.8 – 6.5 Ton
☀️ Heating: 11105 – 120774 BTU/Hr | 0.9 – 10.1 Ton
🔊 Sound pressure: from 43 dBA*
* Sound pressure level measured at 1 m distance in a reverberation test room with the minimum volume of 200 m3.
- Compatible with renewable energy systems – works with solar thermal collectors, heat pumps, and other low-temperature sources for higher energy savings.
- Durable coil design – copper tubes and headers mechanically expanded into corrugated aluminum fins, pressure-tested up to 35 bar with a 16-bar operating limit.
- 0–10 VDC EC motor – delivers up to 30% energy savings compared to AC motors, with smoother speed control, quieter operation, and lower running costs.
- Manual air vent + water purge valve – enables quick and efficient system bleeding for hassle-free maintenance.
- Internal drain pan – in painted steel to safely collect and channel condensate, protecting interiors from leaks, water damage, and moisture issues.
- 25 mm (1”) NBR insulation – double skin thermal barrier that limits heat transfer through the casing, keeping supply air closer to design temperature, especially in humid conditions.
- G2 (MERV 4) filter – captures dust and larger particles to improve indoor air quality and protect the coil.
- I-Type Controllers: Infrared Handset or Wired Wallpad
- Valves: HYDRO+ VALVE Kit with 2/3-way body valve, on-off/modulating actuator (24V or 110-240V), BSPT or NPT connectors, connection piping kit, 2x shut-off valves, strainer and manual balancing valve
- Drain pan: stainless steel
- Electric heater: up to 9 kW
- Filter: G4 (MERV 8) or F8 (MERV 14)
- Air plenum: Supply/Return
- Integrated transformer: converts from 230V to 24V for valve and thermostat compatibility
- Disconnect switch: integrated in control box
- Customization: available upon request (minimum order quantities apply)
Polar Air Control Logic
Polar Air fan coil units provide exceptional control flexibility to meet various application needs. Choose between two types of PCBs.
I-Type Control
Exclusively developed by Polar Air for intelligent control that includes our ADBS technology for ΔT management and group control. Configuration for 2- and 4-pipe models.
Available through ModBus, or compatible with Polar Air Wired Wallpad or Infrared Handset.
24/7 programming
Auto & 3-Speed functions
Sleep function
Auto-Restart function
Dehumidification mode
Adjustable swing louver positioning
Condensate drain pump control
Error diagnostics on unit LED display or Wired Wallpad
Valve control
Dry contact for On/Off applications
Electric heater control
2 x 24V auxiliary contacts for ERVS or dampers
Building Management Systems (BMS) compatible via Modbus
Auto-Dynamic Balancing System with constant ΔT management
255 units group control via ModBus
32 units group control via Wired Wallpad
I-Type Control
Exclusively developed by Polar Air for intelligent control that includes our ADBS technology for ΔT management and group control. Configuration for 2- and 4-pipe models.
Available through ModBus, or compatible with Polar Air Wired Wallpad or Infrared Handset.
24/7 programming
Auto & 3-Speed functions
Sleep function
Auto-Restart function
Dehumidification mode
Adjustable swing louver positioning
Condensate drain pump control
Error diagnostics on unit LED display or Wired Wallpad
Valve control
Dry contact for On/Off applications
Electric heater control
2 x 24V auxiliary contacts for ERVS or dampers
Building Management Systems (BMS) compatible via Modbus
Auto-Dynamic Balancing System with constant ΔT management
255 units group control via ModBus
32 units group control via Wired Wallpad
W-Type Control
Simple yet flexible functionality that is easy to use, allowing for limited LED diagnostics and RPM configuration. Available for 2- and 4-pipe models.
Compatible with external thermostats from a variety of manufacturers.
Choose your own external thermostats
Configure the motor RPMs to your choice
Contact alarm for condensate drain pump and motor
Limited error diagnostics on unit LED display or Wired Wallpad
Project applications & references
Explore recommended applications and recent projects where it’s been successfully installed.
Government
Post Offices · Courthouses · Town Halls · Embassies · Prisons · Military & Emergency Spaces
Healthcare
Hospitals · Clinics · Nursing Homes · Treatment Centers · Laboratories · Morgues
Commercial
Supermarkets · Stores · Shopping Malls · Gyms/Sports Facilities · Museums/Theaters · Airports/Transport Terminals
Industrial
Factories/Plants · Data Centers · Warehouses/Distribution Centers · Wine Cellars/Wineries · Agricultural
Pharmascience
2024
Canada
Quebec
George Brown College 3D Print Lab
2025
Canada
Ontario
Our PASELECT Software is specifically designed to help users choose the most suitable Polar Air fan coils for any project.
Downloads: IOMs, Revits & Guide Specs
Access product resources including installation and operation manuals (IOMs), Revit files, and guide specifications.
Revit Files: PDWD_Double Skin Ducted_4-pipe
|Size: 5 MB - ENRevit Files: PDWD_Double Skin Ducted_2-pipe
|Size: 13 MB - ENIOM: PDWD Double Skin Ducted_METRIC_EC Motor
|Size: 3 MB - EN
Revit Files: PDWD_Double Skin Ducted_4-pipe
|Size: 5 MB - ENRevit Files: PDWD_Double Skin Ducted_2-pipe
|Size: 13 MB - ENIOM: PDWD Double Skin Ducted_IMPERIAL_EC Motor
|Size: 3 MB - ENOur trusted network of authorized representatives ensures you receive exceptional customer service and product availability worldwide.
FAQs: double skin ducted
Why use a double skin casing instead of single skin?
Single skin fan coils can lose efficiency when casing temperatures shift away from design, which shows up as wasted energy, uneven supply air, and sometimes noise from expansion and contraction.
The PDWD’s double skin with 25 mm (1”) NBR insulation creates a proper thermal barrier, reducing heat transfer through the panels. That means the unit holds supply air closer to design values in both cooling and heating modes, whether the project is in a tropical climate, a variable-load office building, or an industrial site with high internal heat gains.
It also reduces casing losses that you might otherwise oversize equipment to offset, while giving fewer performance complaints post-install.
In many projects, double skin isn’t just about condensation or loss/gain control — it’s about delivering predictable, efficient operation under a wider set of conditions.
Do I really need a 4-pipe model?
A 2-pipe system is suitable for buildings that switch seasonally between cooling and heating. But 4-pipe units offer flexibility when zones demand different conditions at the same time.
In hospitals, some wards may need reheating while operating rooms demand cooling. In universities, south-facing classrooms can be in cooling mode while shaded areas require heating. Even in warehouses or night-shift operations, lower loads can create a need for reheating while cooling remains active elsewhere.
A 4-pipe system avoids downtime from seasonal changeover and lets you design around mixed conditions.
How much ESP is actually usable on a PDWD?
The range is 50–200 Pa (0.2–0.8 in.wg), with 150 Pa (0.6 in.wg) recommended as the balanced operating point. That makes the PDWD suitable for longer duct runs, multiple bends, or restrictive ceiling layouts.
In high-rise residential projects, it allows vertical risers with multiple branches; in shopping centres and airports, it handles large, complex duct networks; and in retrofits, it gives you leeway when resistance is higher than expected.
Operating around 150 Pa avoids pushing fans to their limits, which helps control both noise and energy use.
Is the PDWD a good model for tropical climates?
The PDWD’s double skin construction makes it far more resilient in hot, humid environments because it minimizes thermal bridging and condensation, keeping the cabinet dry and stable.
For tropical applications, we can also offer on all Polar Air fan coils:
- Stainless steel drain pans for corrosion resistance.
- Gold fin or specially painted coils to prevent coil deterioration.
- Tropicalized coating on the PCB to protect the electronics from moisture.
- Special electrical configuration for the valve actuators that shields the electrical elements from humidity.
All of these options work together to prevent moisture-related failures, protect the unit’s vital components, and deliver long-term reliability in tropical climates.
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