How to read a heat pump datasheet: A7/W35, A7/W55, COP and heating output
The kW figure in a heat pump’s product title is not enough to select an appliance. Available heating output depends on outdoor air temperature, heating water temperature and the test conditions used by the manufacturer. Two figures can only be compared meaningfully when the underlying conditions are equivalent.
What does A7/W35 mean?
A7/W35 describes a rating point: A7 refers to outdoor air at +7°C, while W35 refers to the leaving water temperature of 35°C. It does not describe the indoor room temperature or average winter weather. W35 is common in low-temperature heating applications, but the required flow temperature must be established for the actual building and heat emitters.
How is A7/W55 different?
At A7/W55, the outdoor air is still +7°C, but the leaving water temperature is 55°C. This point is relevant when assessing radiators and other higher-temperature emitters. Raising water temperature may change available output and electrical demand. Comparing one heat pump’s A7/W35 rating to another one’s A7/W55 rating can therefore be misleading.
Heating capacity, electrical input and COP are not interchangeable
Heating capacity in kW measures delivered heat under a specified test condition. Electrical input, also in kW, describes the electricity consumed in that condition. COP is the ratio between delivered heat and electrical input when the figures refer to the same condition and system boundary. A COP at one rating point is not automatically valid at another.
For illustration only, 9 kW of heat divided by 3 kW of electricity gives COP 3. These figures are not performance claims for any ECO-TEC model. Real product data should identify the measurement method and whether relevant auxiliaries are included.
Why is the modulation range not a guarantee of output in freezing weather?
An inverter heat pump may have a minimum-to-maximum capacity range in its datasheet. That range applies to the stated test point, not every outdoor temperature. The ECO-TEC ECP123-UBV product page, for example, distinguishes A7/W35 from A7/W55 conditions. To select a system for sub-zero weather, request the corresponding cold-weather performance data rather than extrapolating +7°C figures.
What is SCOP, and why should it not be assumed?
SCOP describes seasonal efficiency under a defined standardised assessment. It is different from COP at a single rating point. Any SCOP comparison must use the appropriate climate, application temperature and supporting documentation. We do not assign a SCOP to an ECO-TEC model unless that figure is explicitly supported by its technical documentation. Nor is a declared SCOP a guarantee of a specific building’s electricity bill.
What should a buyer check before comparing two models?
| Parameter | What to check | Why it matters |
|---|---|---|
| Heating output | Outdoor air and leaving water temperatures | Makes ratings comparable |
| COP | Same test point and method | Avoids misleading efficiency comparisons |
| Flow temperature | What the heating system requires at design load | Affects suitability and efficiency |
| Flow and pressure drop | Hydraulic circuit requirements | Enables proper system integration |
| Electrical supply | Phase, current and protection | Avoids installation incompatibility |
| Low-temperature rating | Available output at design outdoor conditions | Verifies that heating demand can be covered |
How to apply this to published ECO-TEC specifications
The ECP123-UBV datasheet and the ECU149-SBY product page both give heating information at stated rating conditions. The latter also specifies an outdoor operating range. These details are useful, but a building’s required output at sub-zero design temperature still needs to be verified separately. Maximum water temperature and minimum operating temperature cannot replace that verification.
Frequently asked questions
Is a heat pump labelled 12 kW sufficient for a building with a 12 kW design heat loss?
Not necessarily. Check the available heating output at the actual design outdoor temperature and required flow temperature, alongside any planned auxiliary heat strategy.
Does a higher COP always mean a better heat pump?
No. The COP values must refer to equivalent rating points and test methods. Cold-weather output, hydraulic compatibility, controls and service requirements also matter.
Can I calculate my yearly bill from a catalogue COP?
Not reliably. Actual electricity consumption depends on building heat loss, weather, flow temperature, defrost behaviour and use. A single-point COP is not a seasonal average.
Next step: try the ECO-TEC sizing calculator for an initial estimate, then request a technical review of the selected model. This guide helps you read the datasheet; it is not a substitute for system design.
