The Overlooked Key to Heat Pump Performance: Understanding Controls

When people talk about heat pumps, the conversation usually starts and ends with hardware: pipework design, compressor efficiency, and refrigerant choice. But in reality, one of the biggest factors that determines whether a system performs well in the field isn’t mechanical at all. It’s how the system is controlled.

At Clade, we see time and again that even the best-designed heat pump won’t perform efficiently or reliably if the controls aren’t properly considered. Control strategy determines how the whole system interacts, responds, and adapts to changing demand, and a solid control strategy is where real-world performance is won or lost.

Understanding the Three Layers of Control

A commercial heat pump system isn’t governed by one controller. It operates across three interconnected layers, each with a distinct role.

1. Unit Controller (Refrigeration Level)

This is the onboard controller managing the refrigeration cycle: compressor speed, expansion valve, defrost, safety protections, and refrigerant envelope.

It ensures the heat pump itself operates safely and efficiently, but it does not manage the wider heating system.

2. Multiplex Controller

This is the core of Clade’s control architecture and the most important part of any installation.

The Multiplex controller manages:

• Temperature differential (ΔT) stability
• Primary flow/return control
• Pump speed and sequencing
• Buffer charging and discharging
• Multiple heat pump coordination
• Night setback and noise-compliance logic
• Protection of refrigerant conditions through return-temperature control

This is where efficiency is won or lost. This is also the layer most often missing or misconfigured in retrofit projects.

3. The Building Management System (BMS)

The BMS manages the secondary side and distributes heat based on occupancy, schedules, and room demands.

Critically, the BMS should not attempt to override or micromanage the heat pump.
Its job is to request heat, not to decide how the heat pump produces it.

When these three layers are aligned, the system is stable, responsive, and efficient. When they aren’t, the system spends its life fighting itself.

Why Controls Are Often Overlooked

In many projects, control design is treated as an afterthought. The focus is on pipework layouts, equipment specification, or hydraulic design, while control logic gets left to commissioning. The problem is that by that point, the system’s limitations are already baked in.

We frequently see issues like:

• Missing sensors
• Incorrect sequencing
• Poor ΔT management
• Primary and secondary pumps fighting each other
• BMS over-control
• Heat pumps being forced into high-return conditions

That’s why our design process at Clade gives controls the same attention as any other part of the system. They’re not optional extras; they’re integral to how the system functions day-to-day.

Designing for Retrofit

Most of Clade’s current projects are retrofits. That means integrating new low-carbon heat pumps into existing building systems that were never designed for them. In this context, controls are often the key to making a retrofit feasible without tearing everything out.

By matching heat pump flow and return temperatures to existing systems, we can simplify control logic and retain much of the secondary-side infrastructure. This reduces costs, minimises downtime, and makes it easier to deliver measurable carbon savings quickly.

Hybrid systems are another area where intelligent control makes all the difference. In these cases, heat pumps handle the base load, while existing boilers cover short-term peaks. With the right sequencing and predictive logic, this combination delivers lower running costs and lower emissions without compromising resilience.

Clade’s Control Philosophy

One of the largest differences between boiler sequencing and heat pump sequencing is how the system is stabilised.

Clade systems use:

• Fixed return temperature control
• Floating flow temperature
• Stable ΔT (typically 10–25°C depending on refrigerant)
• Primary pump modulation through PICVs and pressure-independent control

Controlling on return temperature stabilises the refrigerant cycle and prevents the oscillations that lead to poor efficiency, short-cycling, and excessive compressor wear.

This principle is embedded in our Multiplex controller. It’s also why we pay such close attention to emitter performance, buffer sizing, pump selection, and BMS integration during design.

Why Clade Integrates Controls from Day One

Because we design, manufacture, install, and maintain our own systems our controls are designed into the architecture.

From feasibility through to construction and aftercare, our team ensures the control strategy matches:

• Site heat profile
• ΔT expectations
• BMS configuration
• Pumping arrangements
• Noise requirements
• Electrical limitations
• Refrigerant characteristics

This holistic approach is why Clade systems deliver real site performance.

Talk To Us About Heat Pump Controls

Getting the controls right is what makes the difference between a heat pump system that just runs, and one that performs at its best for years to come. From schematic design and sequencing logic to commissioning and fine-tuning, every stage of control design plays a role in efficiency, reliability, and long-term performance.

But it’s not something you need to be concerned about.

You can leave that to our experienced team of engineers here at Clade, who will support you from system design and installation all the way through to commissioning, monitoring, and optimisation.

With over 35 years of experience working with natural refrigerant heat pumps and integrated control systems, we know what it takes to deliver consistent, efficient, and reliable heating performance, from day one and for the long term.

Just get in touch to discuss your next project or find out how we can help you optimise your system controls.