Many heat pump systems that underperform are not necessarily poorly installed — they are poorly commissioned.

Commissioning is the stage where the system is set up, adjusted, and optimised after installation. If this is not done correctly, even a well-designed system can struggle to heat the property efficiently.

In many of the systems we review, commissioning issues are one of the most common causes of high running costs and poor performance.

🔧 1. Incorrect Flow Rates

One of the most common issues is incorrect system flow rate.

If flow is too low:

• Heat transfer is reduced

• Radiators may feel cooler

• The system may struggle to reach temperature

If flow is too high:

• Reduced efficiency

• Poor temperature drop (ΔT) across emitters

👉 Flow rate must be set correctly based on system design.

🌡️ 2. Incorrect Flow Temperature Settings

Another frequent issue is incorrect flow temperature setup.

• Too high → reduced efficiency and higher running costs

• Too low → property may not heat properly

👉 The system should be balanced between:

• Heat loss

• Radiator output

• Outdoor conditions

🌦️ 3. Weather Compensation Not Set Up Properly

Many systems have weather compensation but:

• It is not enabled

• It is set incorrectly

• The curve is too aggressive or too flat

👉 This leads to:

• Unstable room temperatures

• Poor efficiency

🔁 4. Poor System Balancing

If radiators are not balanced:

• Some rooms overheat

• Others remain cold

• Flow distribution becomes uneven

👉 Proper balancing ensures:

• Even heat across the property

• Stable system operation

⚠️ 5. Incorrect Control Strategy

Controls are often misunderstood.

Common mistakes include:

• Using timers like a gas boiler

• Large temperature setbacks

• Conflicting thermostat and controller settings

👉 Heat pumps should run steadily, not in short bursts.

❄️ 6. Frequent Defrost Issues

If commissioning is incorrect:

• Flow rates may be wrong

• System temperatures unstable

👉 This can lead to:

• Frequent defrost cycles

• Reduced performance

🔍 7. No Verification of System Performance

In some cases, systems are left without proper checks.

Commissioning should include:

• Flow and return temperature checks

• System performance validation

• Control adjustments

👉 Without this, issues go unnoticed.

💡 Real-World Insight

In many systems we review, correcting commissioning settings (without changing hardware) can significantly improve performance and reduce running costs.

Not Sure If Your System Was Commissioned Correctly?

We offer independent technical reviews to assess how your system has been set up.

You’ll receive:

• Review of system settings and performance

• Clear recommendations for improvement

• Simple step-by-step guidance

👉 Ideal if your system is not performing as expected.