Carel is one of the world’s leading manufacturers of controllers, humidifiers, and electronic components for HVAC/R and refrigeration applications. iACS has stocked and supported the Carel range since 2011 and now holds one of the most comprehensive Carel inventories in the UK. Carel’s strength lies in its open‑protocol capability — full BACnet and Modbus support — which aligns with the wider control strategies outlined in The Complete Guide to HVAC Controls and explained in detail in our BACnet vs Modbus Guide.

Carel IR33: Parametric Controllers

The Carel IR33 is a flagship parametric controller series — a versatile, cost-effective range for refrigeration and HVAC applications where the application logic is factory-programmed and the engineer configures behaviour through parameters rather than custom code. The IR33 is available in a wide range of configurations:

  • Temperature inputs — NTC, PTC, Pt100, Pt1000, or thermocouples depending on model suffix
  • Relay outputs — 2 or 4 relays depending on model
  • Analogue outputs — 0–10V or 4–20mA on selected models
  • Communication — pLAN, Modbus, RS-485 on selected models
  • Display options — 4-digit LED display, with optional external display modules

The IR33 series is widely used in cold room controllers, condensing unit controls, packaged chiller controls, and single‑zone HVAC temperature applications. The IR33+ models extend functionality with proportional analogue outputs for modulating valves or fan‑speed control.

For available models and technical variants, you can browse Carel IR33 controllers in the iACS product range.

Carel c.pCO: Programmable IoT Controllers

The c.pCO is Carel's current-generation programmable controller platform and the natural successor to the pCO range. Built on an ARM Cortex-A8 processor running Linux OS, it combines the full programmability of a traditional HVAC controller with modern IoT connectivity and cloud integration — making it the platform of choice for OEMs and controls contractors working on AHUs, chillers, heat pumps, and complex packaged plants.

Hardware and I/O

The c.pCO is available in three hardware configurations — small, medium, and large — to match the input/output requirements of different plant sizes:

  • c.pCO Small — suited to compact packaged equipment and terminal units such as fan coil units (FCUs) and VAV boxes
  • c.pCO Medium — the standard platform for air handling units (AHUs) and medium-complexity plant; supports a broad range of digital inputs, analogue inputs, relay outputs, and analogue outputs
  • c.pCO Large — high-density I/O for complex plant room applications, multi-zone systems, and large AHUs with extensive field device connections

All variants support Carel's pLAN network for connecting operator display terminals and expansion I/O boards, allowing the I/O count to be extended as the application demands.

IoT Connectivity and Remote Monitoring

Where the c.pCO distinguishes itself from earlier platforms is in its built-in connectivity. Standard Ethernet is included on all models, with native support for:

  • HTTPS — secure web server for local browser-based access and configuration
  • FTP — file transfer for data logs, application uploads, and backups
  • MQTT — lightweight messaging protocol for integration with cloud platforms and IoT infrastructure
  • Carel tERA cloud — Carel's own cloud platform for remote monitoring, data logging, fault alerting, and fleet management across multiple sites

For UK estates and facilities management teams, this means real-time performance data and alarm notifications are accessible without the need for a site visit — particularly valuable for remote plant rooms, supermarket refrigeration networks, and multi-site portfolios.

BMS Integration

The c.pCO supports a comprehensive set of industry-standard building management system (BMS) protocols, making it suitable for virtually any integration strategy encountered on UK commercial and industrial projects:

  • BACnet MS/TP and BACnet IP — for integration with BACnet-native BMS platforms
  • Modbus RTU and Modbus TCP — widely used across UK building services
  • LON — legacy protocol supported for existing LonWorks installations

Programming Environment

Applications for the c.pCO are developed and maintained using Carel's c.suite development environment — a graphical IEC 61131-3 compliant programming tool that allows control engineers to write, simulate, and deploy bespoke control logic. The platform is fully backwards-compatible with applications previously written for the pCO3, which simplifies the migration of existing programmes onto the newer hardware without requiring a full redevelopment.

Typical UK Applications

The c.pCO is the controller of choice wherever bespoke control logic and flexible BMS integration are required, including:

  • Air handling units (AHUs) — from simple single-zone units to complex multi-zone systems with heat recovery, humidification, and variable air volume (VAV) control
  • Water-cooled and air-cooled chillers
  • Air source and water source heat pumps
  • District heating and cooling plant rooms
  • Packaged rooftop units
  • OEM equipment where the controller is supplied pre-programmed as part of the unit

For available models and technical variants, you can browse Carel c.pCO controllers in the iACS product range.

IR33 vs c.pCO: Which Should You Choose?

For UK M&E engineers and HVAC controls contractors, the decision between the IR33 and c.pCO typically comes down to the complexity of the application and the degree of customisation required.

Choose the IR33 when:

  • The application is well-defined, and factory logic covers your requirements — cold rooms, condensing units, small packaged chillers, single-zone temperature control
  • Commissioning via parameters is sufficient, and no bespoke programming is needed
  • Budget and panel space are a priority
  • You need a simple, proven controller that can be configured on-site without a laptop or specialist software

Choose the c.pCO when:

  • The application requires bespoke control sequences — custom AHU programmes, heat pump logic, multi-zone plant with complex interlocks
  • BMS integration is required via BACnet or Modbus, with precise mapping of data points to the BMS
  • IoT connectivity, cloud monitoring, or remote access is specified — increasingly common on UK projects under BEMS and energy monitoring requirements
  • You are an OEM supplying a plant with a pre-loaded application, or a controls contractor managing a portfolio of sites
  • The project is migrating from an existing pCO3 platform, and backward compatibility is needed

When in doubt, iACS's technical team can advise on model selection based on your I/O schedule, communication requirements, and application type.

Carel Humidifiers

In addition to controllers, Carel manufactures one of the most comprehensive ranges of commercial humidifiers available — steam humidifiers (humiSteam, heaterSteam), ultrasonic humidifiers (Ultrasonic), and adiabatic humidifiers (humiFog). These technologies are compared in detail in our humidification guide: Steam vs Ultrasonic vs Adiabatic, which explains where each type is most effective. iACS stocks the full Carel humidifier range with same-day despatch on key lines, and you can browse Carel humidifiers to view available models and specifications.

Carel Technical Support at iACS

iACS holds Carel product stocks across the full controller, humidifier, accessory, and spare parts range. You can browse all Carel products directly from our catalogue, or access the full library of manuals and technical documents in our Carel datasheet archive. For a broader context on how these devices fit into modern HVAC control architectures, return to The Complete Guide to HVAC Controls. Our technical team has deep application knowledge of Carel products and can advise on model selection, I/O configuration, software versions, and communication setup. Call our technical sales team or use the trade account enquiry form.