Delivering precise environmental control within a luxury hotel requires more than simply selecting the right heating and cooling equipment.
The control system must respond quietly and accurately, integrate with the wider Building Management System and fit within the physical constraints of the plant area, all while protecting guest comfort across spaces with constantly changing occupancy.
For this project, iACS worked with Air Handlers Northern Ltd to provide bespoke AHU controls for a premium hotel in Kensington, London.
The installation included multiple Air Handling Units serving key amenity spaces, including the hotel restaurant and the Kensington Suite. Each unit incorporated variable-speed EC fans, Daikin R32 DX heating and cooling, staged electric reheating, filtration, face-and-bypass dampers and fire-and-smoke shutdown interfaces.
Because available plant space was highly restricted, conventional external control panels were not suitable.
iACS therefore engineered complete iSMART control systems onto compact backplates designed to be mounted directly inside the AHU casings. The solution also integrated third-party Daikin DX equipment, provided BACnet/IP communications to the hotel BMS and introduced the additional temperature sensing required for stable electric heater regulation.
The project was successfully commissioned in January 2026, with the DX, heating and BMS sequences fully proven before handover.
What This Project Covered
This project demonstrates how iACS delivered:
- Bespoke internal AHU control backplates
- Space-saving control panel engineering
- Daikin R32 DX integration
- Hybrid DX and electric heating control
- Variable-speed EC fan management
- Air-off temperature sensing
- Face-and-bypass damper control
- Filter differential-pressure monitoring
- BACnet/IP BMS integration
- Fire and smoke shutdown interlocks
- Third-party wiring diagnostics
- Factory quality assurance
- On-site commissioning
Table of Contents
- Project Overview
- Why Hotel Amenity Spaces Need Precise HVAC Control
- The Air Handling Unit Configuration
- The Space Constraint
- Designing the Internal Control Backplates
- Integrating the Daikin DX System
- Hybrid DX and Electric Heating
- Why the Air-Off Temperature Sensor Was Essential
- BACnet/IP Integration
- Fire, Smoke and Safety Interlocks
- Diagnosing the Third-Party DX Wiring Fault
- Final Commissioning
- The Project Outcome
- Before and After the iACS Solution
- Why This Project Matters
- Key Capabilities Demonstrated
- Looking for a Bespoke Hotel AHU Controls Partner?
1. Project Overview
Sector
Hospitality & Leisure
Application
Hotel restaurant and premium suite climate control.
Customer
Air Handlers Northern Ltd
End User
Queen’s Gate Hotel
Location
Kensington, London
Project Timeline
- Engineering and wiring approved: April 2025
- Site commissioning: 19–20 January 2026
- Final reports issued: January 2026
iACS Scope
- Bespoke control backplate design
- Control panel manufacture
- Application software
- Daikin DX interface engineering
- BACnet/IP integration
- Technical design consultation
- Factory quality testing
- On-site commissioning
- Third-party wiring diagnostics
AHU Applications
The project included multiple AHUs, including:
- AHU 01 serving the Kensington Suite
- AHU 03 serving the hotel restaurant
Control Platform
iSMART control backplates built around Carel pCO5+ Small controllers with pGD1 displays.
Project Status
Successfully commissioned and handed over.
2. Why Hotel Amenity Spaces Need Precise HVAC Control
Hotel restaurants, event suites and premium guest areas can experience rapid changes in occupancy.
A restaurant may move from quiet preparation periods to full service within a short time, while event spaces can change from empty to heavily occupied between bookings.
The HVAC system must therefore respond to:
- Changing occupancy
- Internal heat gains
- Outdoor temperature
- Heating demand
- Cooling demand
- Air quality
- Guest comfort expectations
- Fire and smoke inputs
Temperature instability in these spaces can quickly become noticeable to guests.
The control system must provide a smooth response without creating excessive noise, temperature overshoot or frequent equipment cycling.
3. The Air Handling Unit Configuration
The AHUs were configured with a combination of ventilation, heating and cooling equipment designed to serve the hotel’s amenity spaces.
The mechanical systems included:
- Variable-speed supply EC fans
- Variable-speed return EC fans
- Daikin R32 DX condensers
- EKEXVA electronic expansion valves
- EKEACB DX interface control boxes
- 9kW electric heater batteries
- Three 3kW electric heating stages
- Face-and-bypass dampers
- Bag filters
- Panel filters
- Differential-pressure switches
- Fire and smoke damper interfaces
The control system needed to coordinate these components as one complete operating strategy.
4. The Space Constraint
Plant-room space within central London hotels is often limited.
Standard external control panels require wall space, containment and longer cable routes between the panel and the AHU components.
For this project, an external enclosure was not considered practical.
The controls therefore had to:
- Fit directly within the AHU casing
- Remain accessible for testing
- Accommodate the controller and electrical devices
- Support DX communications
- Support BMS connectivity
- Protect the control equipment
- Avoid increasing the external footprint of the AHU
This required a bespoke approach rather than a standard control panel format.
5. Designing the Internal Control Backplates
iACS designed compact control backplates that could be mounted directly inside the Air Handling Units.
The controls were arranged within an approximate 500 × 400mm footprint, allowing the AHU manufacturer to integrate the complete control package during production.
Each backplate included:
- Carel pCO5+ Small controller
- pGD1 operator display
- Electrical protection
- Fan controls
- Heater outputs
- Damper outputs
- Sensor terminals
- DX interface connections
- BACnet/IP communications hardware
Benefits of the Backplate Design
The internal arrangement provided several advantages:
- No external panel required
- Reduced plant-room footprint
- Shorter internal wiring routes
- Simplified site installation
- Easier factory integration
- Cleaner finished installation
- Reduced containment requirements
The project demonstrates how iACS can adapt control hardware around the mechanical equipment rather than forcing the AHU manufacturer to work around a standard enclosure.
6. Integrating the Daikin DX System
The primary heating and cooling was provided through Daikin R32 DX equipment.
The installation included ERA-series condensers, EKEXVA expansion valves and EKEACB interface control boxes.
The iSMART controls needed to communicate with the Daikin system using the correct combination of:
- 0–10V control signals
- Volt-free enable contacts
- Heating and cooling selection
- Safety interlocks
- Alarm feedback
The controller calculated the thermal demand and then instructed the DX system to operate in the required mode.
This allowed the AHU to shift between heating and cooling based on the live temperature requirements of the space.
7. Hybrid DX and Electric Heating
The AHUs also included 9kW electric heater batteries arranged as three 3kW stages.
These heaters provided supplementary heat and reheating where required.
The hybrid strategy allowed the system to combine:
- Primary DX heating
- Primary DX cooling
- Staged electric heating
- Temperature trimming
- Rapid recovery
The iSMART controller coordinated the two heating sources to avoid unstable operation.
This required careful sequencing so the electric heater supported the DX system rather than operating unnecessarily or causing temperature overshoot.
8. Why the Air-Off Temperature Sensor Was Essential
One of the most important engineering decisions took place during the design phase.
The original mechanical proposal intended to use the electric heater for close temperature regulation without installing a dedicated air-off temperature sensor downstream of the heater.
iACS identified this as a significant control risk.
Without an air-off sensor, the controller would not have a direct measurement of the temperature leaving the heater.
It would instead rely on a sensor positioned further away from the heating source, introducing delay into the control response.
The Risk of Thermal Lag
This could have caused:
- Slow heater response
- Temperature overshoot
- Unstable P.I.D. control
- Repeated heater staging
- Inconsistent comfort
- Excessive energy use
iACS recommended adding a dedicated downstream sensor, identified as TS4.
The mechanical contractor accepted the recommendation, and iACS updated both the software and the wiring diagrams to incorporate the new input.
This proactive engineering decision addressed the potential problem before the AHUs reached site.
9. BACnet/IP Integration
The hotel required the AHUs to communicate with its central Building Management System.
Each controller was equipped with a pCOWeb Ethernet card, providing BACnet over IP connectivity.
The BMS could monitor information including:
- AHU operating status
- Supply temperature
- Return temperature
- Fan speeds
- Fan alarms
- Heating demand
- Cooling demand
- Electric heater stages
- Filter alarms
- Fire and smoke status
- General faults
BACnet/IP reduced the need for multiple hardwired BMS signals while providing the facilities team with central visibility of the restaurant and suite systems.
10. Fire, Smoke and Safety Interlocks
The AHUs incorporated hardwired fire and smoke shutdown inputs.
During a valid emergency condition, the controls were required to override normal comfort operation and place the units into the defined safe state.
The fire or smoke input took priority over:
- Heating demand
- Cooling demand
- Fan control
- Scheduled operation
- Normal BMS commands
This ensured the ventilation equipment responded in accordance with the building’s wider life-safety strategy.
11. Diagnosing the Third-Party DX Wiring Fault
Following site installation, the Daikin DX equipment failed to enable correctly.
The iACS controls were issuing the required demand, but the external DX units did not respond.
Through technical troubleshooting, iACS identified an issue within the third-party field wiring.
The Daikin EKEACB interface required a link between terminals T1 and T2.
This link had not been installed by the site electricians.
Without it, the enable circuit remained incomplete.
iACS guided the site team through the correction, after which the DX equipment operated as intended.
This is a clear example of why successful commissioning must verify the complete signal path, from controller output to third-party equipment response.
12. Final Commissioning
The commissioning process included:
- Control backplate inspection
- Sensor verification
- EC fan testing
- Fan balancing
- DX heating tests
- DX cooling tests
- Electric heater staging
- Air-off temperature verification
- Damper testing
- Filter alarm checks
- Fire and smoke shutdown tests
- BACnet/IP communication checks
- Alarm verification
The hybrid DX and electric heating sequences were proven successfully, and the BMS communications were established.
Final commissioning reports were then issued to confirm completion.13. The Project Outcome
The completed project delivered:
- Compact internal AHU controls
- Successful Daikin DX integration
- Stable electric heater regulation
- Accurate downstream temperature sensing
- Variable-speed EC fan control
- BACnet/IP connectivity
- Fire and smoke shutdown integration
- Successful site commissioning
- Completed handover documentation
The hotel facilities team gained central BMS visibility over both the restaurant and Kensington Suite systems.
14. Before and After the iACS Solution
| Project Requirement or Risk | iACS Solution |
| Limited plant-room space | Compact internal AHU control backplates |
| Third-party Daikin DX equipment | Bespoke 0–10V and volt-free interface strategy |
| Electric heater required for regulation | Dedicated TS4 air-off sensor added |
| Risk of thermal lag and temperature swings | Software and wiring updated before manufacture |
| Site DX units failed to start | Missing T1–T2 interface link identified |
| Central hotel monitoring required | BACnet/IP integration through pCOWeb |
| Emergency shutdown required | Hardwired fire and smoke interlocks |
15. Why This Project Matters
This project demonstrates the importance of involving a controls specialist early in the mechanical design process.
Had the electric heater been installed without the downstream air-off sensor, the completed system could have suffered from unstable temperature control.
By identifying the issue during design, iACS prevented a site problem before it occurred.
The project also demonstrates the value of bespoke physical engineering.
Rather than using a standard external panel, the complete controls package was redesigned to fit inside the AHU.
The final result combined space-saving hardware, advanced DX integration, proactive engineering and successful BMS connectivity within one coordinated solution.
16. Key Capabilities Demonstrated
- Bespoke internal AHU control backplates
- Carel pCO5+ programming
- Daikin R32 DX integration
- EKEACB interface control
- Hybrid DX and electric heating
- P.I.D. temperature control
- Air-off sensor strategy
- BACnet/IP integration
- Fire and smoke interlocks
- Third-party wiring diagnostics
- On-site commissioning
Looking for a Bespoke Hotel AHU Controls Partner?
Hotel HVAC systems need to deliver comfort, reliability and quiet operation while fitting within demanding architectural and plant-space constraints.
At iACS, our services include:
- AHU control panel design
- Compact backplate solutions
- DX integration
- Electric heater control
- EC fan management
- BACnet and Modbus communications
- Fire and smoke interfaces
- Factory testing
- Installation support
- Site commissioning
- Troubleshooting and optimisation
Whether you are supplying AHUs for a hotel restaurant, function suite, guest accommodation or another premium commercial application, iACS can engineer a complete control solution around the mechanical and operational requirements of the project.