Product datasheet

AReCoS embedded controller

One controller, designed to set every actuator in the refrigerant circuit together, for commercial and industrial refrigeration, chiller plants and heat pumps.

Rev 1.0 · Sep. 2026 U.S. patent allowed · 18/592,624 Runs on the equipment · no cloud info@arecos.net

What it is

A model of the machine, running on the machine.

The AReCoS embedded controller is designed to carry a first-principles model of the refrigerant cycle — the coils, the compressor, the expansion valve and where the charge sits — run that model on the machine, reconstruct from an ordinary pressure and temperature sensor set the conditions inside the coils that no practical sensor reports, and set the compressor, expansion valve, fans, blowers and pumps at the same instant. Every actuator moves every pressure and temperature in the circuit, so they are decided together rather than left to a separate loop on each device to settle out.

It is the same core controller AReCoS is building into its own all-season heat pump rooftop unit and residential heat pump.

Class: Embedded controller for a vapor-compression circuit
Designed for: Commercial and industrial refrigeration, chiller plants, and reversible air-source heat pumps and rooftop units
Refrigerants: HFC and HFO blends, ammonia R-717, CO₂ R-744. The refrigerant is a property of the machine, not of the control architecture: it is supplied as a parameter and its properties are looked up, rather than written into the control law.
Hardware: Controller hardware, sensor and actuator channel counts, and the enclosure are defined with you during the evaluation, around the machine it will run.

Why one controller

What it replaces.

A refrigeration system or chiller plant runs several controllers at once — a rack or unit controller, case or circuit controllers, separate loops for condenser fans and pumps — each specified and tuned on its own, and all of them interacting.

A cloud optimizer works above them, at the setpoint level. The controllers underneath are unchanged, still interact, and stop receiving an answer when the link does. The AReCoS controller works at the machine's own dynamics, at the actuator, and still takes its goals from above. A site that has this keeps its supervisory system.

What it does

Commissioned from the machine, not tuned loop by loop.

The controller is designed to be set up from the machine's own characteristics — its coils, compressor, valve, refrigerant and actuator ranges — rather than tuned device by device on site, and to cut the site visits spent retuning loops. One design covers the machine's operating range rather than one favorable rating condition. On the machine it is designed to carry these functions, as one decision rather than as separate loops.

Sets every actuator together: Compressor, expansion valve, fans, blowers and pumps computed as one set of commands, at the machine's own dynamics.
Holds the delivered temperature: The air off the coil, or the temperature the machine is set to deliver.
Regulates superheat: Evaporator superheat held together with capacity, not on a valve loop of its own.
Sets the working pressures: Evaporating and condensing pressure set as part of the same decision, rather than as separate head-pressure and suction-pressure resets.
Follows subcooling: On a subcritical machine, condenser subcooling read as where the charge sits.
Counts the whole power draw: Designed to hold the required duty on the actuator combination that draws the least total electrical power, with the fans and blowers counted alongside the compressor rather than the compressor alone.
Works from what no sensor reports: The conditions inside the coils, reconstructed from the pressures and temperatures a standard sensor set already provides, so the controller acts on the state of the refrigerant rather than on a thermostat reading.
Screens its own commands: A second model is designed to screen the controller's commands for likely component failures before they are sent.

Where it sits

Under your supervisory system, over the actuators.

The controller sits under the building or plant system, not in place of it. That system keeps the goals — setpoints, schedules, demand-response signals — and the controller decides how the compressor, valves, fans and pumps meet them. It owns the actuators and nothing above them, and each machine keeps its own hard-wired safeties.

Everything runs on the equipment. No cloud service and no remote optimizer in the control path: the controller keeps deciding when the connection is gone, and no site data has to leave the site for it to run.

If the controller loses power, stops or is taken out of service, its outputs are designed to go to the fail-safe positions set for your machine, normally the compressor off and the expansion valve closed. Those positions are held by the actuators and the wiring rather than by the controller, so the machine's own hard-wired safeties act without it.

The field bus, the points list and the supervisory interface are agreed with you during the evaluation, and the fail-safe position of every output is fixed there.

The machine's own hard-wired safeties are not in the controller's path.

Phases

Starting, stopping and switching, not just steady running.

Controls are usually designed for the machine once it has settled, and starting, stopping and switching are left to timers and interlocks. Those are the phases in which refrigerant moves between the coils and equipment is damaged. The controller is designed to run the machine through all four as one control problem.

Startup: Bringing the machine up to capacity without liquid returning to the compressor while the charge redistributes between the coils.
Running: Holding the duty as the load and the ambient move.
Shutdown: Following the refrigerant as it redistributes between the coils when the machine comes to rest, so the next start begins from a known state.
Changeover: Carrying the machine through each switch between heating and cooling, so it comes out with the refrigerant where the next phase needs it.

What it fits

Not tied to one compressor, one refrigerant or one maker.

A different machine is described to the controller as data rather than as new software.

Circuits: Single-circuit machines with a variable-speed compressor, an electronic expansion valve and air movers; machines carrying more than one coil and more than one expansion valve on one controller.
Components: Designed to run standard compressors, valves, fans, blowers and pumps from different manufacturers. No proprietary sensor and no proprietary actuator.
Both directions: On reversible machines the design is carried through cooling and heating separately, each holding the air stream that serves the space in that mode.
A different machine: The same design and verification path is run against its parameters.
The plant: One controller runs one refrigerant circuit. Staging between machines, scheduling and demand limiting stay with the plant or building system.

Signals

What it reads, and what it drives.

In place of a channel count, the measurements the controller works from and the devices it commands.

Reads, refrigerant: Suction and discharge pressure, the measurements the control and the estimate are built on, with refrigerant temperature around the circuit: compressor outlet, condenser outlet, evaporator outlet and each additional heat exchanger.
Reads, air and fluid: Air temperature into and out of the coils and ambient air temperature; on a machine with a fluid loop, entering and leaving fluid temperature. Refrigerant mass flow and compressor current where they are fitted.
Designed to estimate: The conditions inside the coils, from those same readings.
Drives: Variable-speed compressor; electronic expansion valve, closed to open; the reversing valve on a reversible machine; fans, blowers and pumps where the machine carries them. Each on its own channel.
Takes from above: Delivered-temperature setpoint, schedules, demand-response signals, and blower or fan overrides, as reference commands from the building or plant system.

Protection and conditioning

What runs on the controller itself.

Each of these is computed on the controller from the sensors the machine already carries, not in a supervisory layer above it.

Superheat and subcooling: Computed on the controller from its own pressure and temperature readings against a saturation table it holds, with no added instrumentation.
Command range: Every command is held inside the actuator's commanded range before it leaves the controller.
Rate limits: Each channel carries its own rate limit, so the controller cannot slam an actuator.
Compressor pressure limit: The compressor command is screened against a maximum discharge pressure before it is sent.
Measurement conditioning: Temperature, pressure and flow measurements are each conditioned on their own terms, so one noisy channel does not slow the rest down.

The record

What stands behind this sheet.

The patent record and the bench test are public documents, readable today without calling us.

U.S. patent allowed: Application 18/592,624, "Control systems, methods, and algorithms to optimize vapor-compression systems, including refrigeration, heat pump and chiller operations", filed Mar. 1, 2024. Notice of Allowance mailed Jul. 15, 2026; issue fee paid. The patent number is assigned at issue. Inventor: Ahmed Hussein.
Published application: US 2024/0295337 A1, published Sep. 5, 2024: the architecture in full. Google Patents updates weeks after the USPTO and may still show the application as pending; the USPTO record shows the Notice of Allowance.
Test on real equipment: An early version of this controller ran a cooling test on the AReCoS bench vapor-compression prototype, reading its own refrigerant and air temperature sensors and driving every actuator on the rig: its compressor, electronic expansion valve and blower — FIGS. 4 to 7 of US 2024/0295337 A1. That rig cools only and carries no pressure instrumentation.
Validation program: A validation program with a U.S. Department of Energy national laboratory on rooftop-unit energy optimization, with building supervisory integration, October 2025 to April 2027.
Engineering record: A documented model of the refrigerant cycle and a repeatable design and verification run: each controller is checked against the full physics model of the machine, with sensor and actuator response included, across a range of operating points rather than at one.

How to buy

We fit the controller to your machine and supply it.

It runs on your refrigeration system or chiller plant, under the supervisory system you already have.

The evaluation starts with your machine: its coils, compressor, valve, actuators and refrigerant become the model the controller carries.

Let's talk.

Tell us what you run: a refrigeration system, a chiller plant, or a machine you build.

Email info@arecos.net

625 Kenmoor Ave SE, Suite 350
Grand Rapids, Michigan 49546