9 kw Heat Pump
Custom Colors
The 9 kW heat pump is the largest unit on the compact residential platform in the Legom Monoblock DC Inverter range, suited to medium and larger homes and to older properties where heat loss is higher. It is an air source, air-to-water unit running on R32 refrigerant with a full DC inverter twin rotary Panasonic compressor, delivering heating, cooling, and domestic hot water from a single outdoor unit and operating down to -35°C ambient.
9 kW Heat Pump Specifications
Full published parameters for the 9 kW model, Legom Monoblock Series DC Inverter Heat Pump.
| Parameter | 9 kW — QB KFXFC-009SRI |
|---|---|
| Heating capacity range | 3.5 to 10.0 kW |
| Domestic hot water heating | |
| Heating capacity | 10 kW |
| Water yield | 215 L/h |
| Input power | 2.31 kW |
| COP | 4.32 |
| Operating current | 10.4 A |
| Heating A7/W35 | |
| Heating capacity | 9 kW |
| Input power | 2.02 kW |
| COP | 4.46 |
| Operating current | 9.0 A |
| Heating A7/W45 | |
| Heating capacity | 9 kW |
| Input power | 2.61 kW |
| COP | 3.45 |
| Operating current | 11.7 A |
| Cooling A35/W7 | |
| Cooling capacity | 6.5 kW |
| Input power | 2.28 kW |
| EER | 2.85 |
| Operating current | 10.2 A |
| ERP energy label | |
| ERP at 35°C | A+++ |
| ERP at 55°C | A++ |
| Compressor | |
| Type | DC inverter twin rotary |
| Brand | Panasonic |
| Capacity modulation | Stepless, 20% to 120% |
| Other components | |
| Expansion valve | Electronic expansion valve |
| Air side heat exchanger | Hydrophilic aluminium fin heat exchanger |
| Water side heat exchanger | Plate heat exchanger |
| Fan system | |
| Fan type | Low noise axial fan |
| Motor type | Brushless DC motor |
| Motor brand | NIDEC / SiGe |
| Fan quantity | 1 |
| Water side | |
| Water port size | G1.0 DN25 |
| Water yield | 1.72 m³/h |
| Water pressure loss | 25 kPa |
| Expansion tank | Not included |
| Noise, dimensions and weight | |
| Noise level | ≤55 dB(A) |
| Unit dimensions (W×D×H) | 1075 × 480 × 805 mm |
| Packing dimensions | 1165 × 530 × 925 mm |
| Net weight | 80 kg |
| General | |
| Refrigerant | R32 (GWP 675) |
| Minimum ambient operating temperature | Down to -35°C |
| Cabinet colours | 11 finishes available |
| Certification | CE, RoHS |
| OEM / ODM | Available |
Reading the COP figures. At 7°C outdoor air producing 35°C water the unit achieves a COP of 4.46, delivering 9 kW of heat from 2.02 kW of electrical input. Producing 45°C water from the same outdoor conditions, COP falls to 3.45. Both figures describe the same machine. This is why the emitter matters as much as the heat pump: an underfloor system running at 35°C extracts roughly 29% more heat per unit of electricity than radiators demanding 45°C.
Important: Water Connections Step Up to DN25
This is the specification detail most likely to catch out an installer moving up from the smaller models, and it is worth flagging before anything else.
The 5 kW and 6 kW units use G3/4 DN20 water connections. The 9 kW unit steps up to G1.0 DN25. The reason is flow rate: this unit circulates 1.72 m³/h against 1.38 m³/h on the 6 kW, and forcing that through DN20 pipework would create excessive pressure loss and velocity.
Plan the pipework at design stage, not on site. If you are replacing a 6 kW unit with a 9 kW, or quoting a project where the capacity may be revised upward during design, confirm the connection size early. Reducing DN25 down to DN20 at the unit defeats the purpose and introduces a restriction exactly where flow matters most.
The 16 kW model uses the same G1.0 DN25 connections, so a project designed around DN25 pipework can accommodate either the 9 kW or the 16 kW without reworking the hydraulics.
Same Cabinet as the 6 kW, 50% More Output
There is a genuinely useful engineering point in this model that does not appear in the headline figures.
The 9 kW unit measures 1075 × 480 × 805 mm, exactly the same as the 6 kW unit, and shares its packing dimensions. It is 10 kg heavier at 80 kg against 70 kg, and it uses the same single low-noise axial fan. What changes is output: 9 kW instead of 6 kW at A7/W35, a 50% increase within an identical footprint.
For installations where the outdoor unit position is constrained, whether by a narrow side passage, a balcony, or a planning restriction on visible plant, this matters. Stepping from 6 kW to 9 kW costs nothing in space and only marginally in weight and noise, at ≤55 dB(A) against ≤54 dB(A).
Efficiency does not drop when you step up
The other point worth noticing is slightly counterintuitive. The 9 kW unit achieves a COP of 4.46 at A7/W35, which is higher than the 6 kW model's 4.42. Stepping up in capacity here does not cost efficiency.
The reason is that these are all inverter-driven units on the same platform, and the larger heat exchanger surface in the 9 kW model offsets the greater compressor duty. It means the usual assumption that a smaller unit is inherently more efficient does not hold across this part of the range, and the sizing decision can be made purely on load and hot water demand rather than trading capacity against efficiency.
| Consideration | 6 kW | 9 kW |
|---|---|---|
| Heating output range | 3.0–8.0 kW | 3.5–10.0 kW |
| COP at A7/W35 | 4.42 | 4.46 |
| Hot water capacity | 8 kW, 172 L/h | 10 kW, 215 L/h |
| Cooling capacity | 5 kW | 6.5 kW |
| Unit dimensions | 1075 × 480 × 805 mm | 1075 × 480 × 805 mm |
| Net weight | 70 kg | 80 kg |
| Noise | ≤54 dB(A) | ≤55 dB(A) |
| Water port | G3/4 DN20 | G1.0 DN25 |
| Minimum modulated output | 3.0 kW | 3.5 kW |
Is a 9 kW Heat Pump the Right Size?
Capacity should be matched to the building's calculated heat load rather than its floor area alone. A 9 kW unit generally suits a medium to large home, or an older property of moderate size where insulation is weaker and heat loss consequently higher.
Its modulation range runs from 3.5 to 10.0 kW. The upper figure gets the attention, but the 3.5 kW minimum deserves equal consideration. On a mild spring day a well-insulated home may only need 2 to 3 kW of heat, and this unit cannot go below 3.5 kW. It would produce more heat than the building needs, reach the set point, shut off, and restart, cycling through exactly the mild months that make up most of the heating season.
Oversizing is a real error, not a safety margin. A heat pump one size too large spends most of the year unable to modulate low enough, cycling instead of running steadily, which reduces seasonal efficiency and increases compressor wear. Specify the 9 kW when the calculated load genuinely sits in its range, and have a qualified installer perform a heat loss calculation rather than estimating from floor area.
When the 9 kW is the right choice
- The calculated heat load sits between roughly 6 and 9 kW
- The property is a larger home, or an older one with weaker insulation
- Domestic hot water demand is high, with 10 kW capacity at 215 litres per hour
- Cooling demand is significant and 6.5 kW of cooling capacity is useful
- The outdoor unit position is space-constrained but needs more output than the 6 kW provides
- The system design already specifies DN25 pipework
If your calculated load is nearer 4 to 7 kW, the 6 kW model will modulate better through mild weather and uses DN20 connections. If it exceeds 10 kW, or the building is a light commercial property, look at the 16 kW model instead.
Inside the Unit
A heat pump does not generate heat, it moves it. Refrigerant evaporates at low temperature while absorbing heat from outdoor air, the compressor raises its pressure and temperature, and that heat transfers into the water circuit through the plate heat exchanger before the electronic expansion valve drops the pressure and the cycle repeats. Because the unit transports existing energy rather than creating it, it delivers several units of heat per unit of electricity, which is what produces a COP above 1.
Key Technologies
High Efficiency Full DC Inverter Compressor
Integrating cutting-edge technology, our HVAC systems feature a high-performing DC inverter compressor and DC brushless fan motor. This innovative configuration enables seamless 20% to 120% stepless capacity adjustment. By intelligently adapting to the real-time load requirements, the compressor and fan automatically modulate their speeds during operation. This dynamic adjustment minimises energy consumption, allowing the unit to operate at an optimised level, precisely meeting the desired output while significantly reducing energy costs.
The 9 kW model uses a Panasonic twin rotary compressor paired with a NIDEC or SiGe brushless DC fan motor. Modulation across the 3.5 to 10.0 kW range means the unit spends most of the heating season running steadily at partial output rather than cycling, which both improves seasonal efficiency and reduces mechanical wear on the compressor.
Verified Efficiency: ERP A+++ and COP 4.46
The 9 kW unit carries an ERP rating of A+++ at 35°C and A++ at 55°C, the European energy label classification for space heaters. At A7/W35 test conditions it achieves a COP of 4.46, delivering 9 kW of heat output from 2.02 kW of electrical input. For domestic hot water the COP is 4.32.
Three factors determine what efficiency you achieve in service. The flow temperature required has the largest influence, demonstrated by this unit's own figures: 4.46 at 35°C water against 3.45 at 45°C. Outdoor temperature is the second, since colder air holds less extractable heat. Building insulation is the third, because a leaky building forces higher flow temperatures and pushes the unit into its less efficient range.
R32 Refrigerant: Energy Saving and Environmental Protection
R32 contributes greatly to environmental protection, with a low Global Warming Potential of 675, just 32% of R410A's 2088. In the same heat pump system, its lower liquid density means the charge amount of R32 is less than that of R410A, which brings higher economic efficiency.
The heat needed to evaporate R32 is greater than that of R410A, so the required mass flow rate per unit is smaller and the COP is higher. We not only take care of your family but also contribute to protecting the earth.
There is a commercial dimension worth noting for distributors. Under the European F-Gas Regulation and equivalent rules elsewhere, high-GWP refrigerants face progressive restriction, which makes equipment charged with them harder and more expensive to service over time. Sourcing R32 today avoids selling customers into a future servicing problem.
Stable Running at -35°C
The 9 kW unit is engineered to keep operating in ambient temperatures as low as -35°C, well beyond the range in which many standard air source units lose usable output. This is what allows the model to serve as a primary heat source in cold-climate markets rather than a supplementary one.
Two elements make this possible. The full DC inverter compressor can raise its speed to compensate as the heat available in outdoor air falls, sustaining output where a fixed-speed unit simply cannot. The intelligent defrost system then clears frost from the air-side heat exchanger without the frequent, disruptive cycles that undermine cold-weather comfort in simpler designs.
Output does decline as ambient temperature drops, which is unavoidable physics for any air source heat pump rather than a limitation of this model. Cold-climate projects should therefore be sized against the local design temperature rather than the nominal rating.
Automatic Intelligent Defrosting
In cold, humid conditions frost forms on the outdoor coil and must be cleared, but how a heat pump manages that process has a large effect on comfort. Demand-based defrosting initiates a cycle only when frost is actually detected, rather than running on a fixed timer.
The result is concentrated, efficient defrosting completed in around three minutes, followed by extended heating periods of up to 90 minutes. An ordinary defrost curve, by contrast, shows frequent and incompletely effective cycles with short heating periods between them, which prevents the indoor temperature from stabilising and produces the sudden drops in warmth occupants notice and complain about.
An anti-freezing sensor at the base of the unit detects ice accumulation and manages protection automatically at low ambient temperatures.
Applications for the 9 kW Heat Pump
Larger homes and older properties
This is the model's core application. At 9 kW output with modulation up to 10 kW, it covers medium to large homes, and it suits older properties where insulation is weaker and the calculated heat loss consequently higher. In renovation projects where insulation improvements are planned but not yet complete, the additional headroom over the 6 kW model provides useful margin.
Underfloor heating
The most efficient application, and the unit's figures show why. Underfloor heating performs at 30 to 45°C flow temperature, and at 35°C this model reaches a COP of 4.46 against 3.45 at 45°C. The 9 kW unit supplies low-temperature water to a manifold that splits flow between individual floor heating pipe loops, each controlled by a thermal actuator responding to its own room thermostat. At this capacity a multi-zone manifold is typical, so specify the branch count against the number of heating zones.
High domestic hot water demand
At 10 kW of hot water heating capacity and 215 litres per hour with a COP of 4.32, this unit suits households where hot water is drawn heavily. That is roughly 25% more hot water production than the 6 kW model and 67% more than the 5 kW, which makes it appropriate for larger families or properties with several bathrooms in simultaneous use.
Radiator central heating
The unit can replace a gas or oil boiler feeding radiators, and at this capacity that is a common application in older properties. One caveat applies clearly from the specification: radiators sized for 70 to 80°C boiler water will demand high flow temperatures, and COP falls from 4.46 to 3.45 between 35°C and 45°C alone. Oversizing the radiators so they perform at lower temperatures preserves the efficiency benefit, and this should be assessed before conversion rather than discovered afterwards.
Summer cooling
The unit is reversible, delivering 6.5 kW of cooling capacity at A35/W7 with an EER of 2.85. In markets with a genuinely hot summer, this is enough cooling for a medium to large home from the same equipment that heats it in winter.
Installation clearances affect performance, not just access. The outdoor unit needs unobstructed airflow on all sides to absorb and reject heat effectively, and restricting it reduces both output and efficiency. At 1075 × 480 × 805 mm and 80 kg, plan the mounting position and access route before delivery, and site the unit away from bedroom windows given its ≤55 dB(A) rating.
9 kW Compared with the Wider Range
| Parameter | 5 kW | 6 kW | 9 kW | 16 kW |
|---|---|---|---|---|
| Model | QB KFXFC-005SRI | QB KFXFC-006SRI | QB KFXFC-009SRI | QB KFXFC-016SRI |
| Heating range (kW) | 2.0–6.0 | 3.0–8.0 | 3.5–10.0 | 6.5–18.0 |
| COP at A7/W35 | 4.5 | 4.42 | 4.46 | 4.53 |
| Hot water capacity (kW) | 6 | 8 | 10 | 18 |
| Water yield (L/h) | 129 | 172 | 215 | 387 |
| Cooling capacity (kW) | 4 | 5 | 6.5 | 14 |
| Noise dB(A) | ≤52 | ≤54 | ≤55 | ≤56 |
| Water port | G3/4 DN20 | G3/4 DN20 | G1.0 DN25 | G1.0 DN25 |
| Fan quantity | 1 | 1 | 1 | 2 |
| Net weight (kg) | 60 | 70 | 80 | 120 |
| Best suited to | 2–3 bedroom homes | Medium homes | Medium to large homes | Large homes, light commercial |
All four capacities share the same platform: R32 refrigerant, DC inverter twin rotary compressor, reversible heating and cooling, ERP A+++ at 35°C, operation to -35°C, and CE and RoHS certification. The 9 kW unit is the largest single-fan model in the range, sharing DN25 water connections with the 16 kW while retaining the compact cabinet of the 6 kW.
OEM and ODM Customization
Our team offers expert guidance and customization to suit your product needs. Prior to commitment, provide written confirmation of the key parameters: required heating and cooling capacity, cabinet colour, controller and connectivity requirements, and branding specification. We employ advanced modelling to ensure project confidence, and product development maintains strict confidentiality, safeguarding your project throughout.
Available customization covers cabinet colour across the eleven finishes shown above, logo and nameplate, packaging, and controller and operating parameter configuration for private-label supply. Samples are produced and performance tested against your specification before production commitment, and performance and leak test records are available for production batches. See the full OEM and ODM service for details, or read about our heat pump OEM factory and how the process works.
Frequently Asked Questions
What size house does a 9 kW heat pump heat?
A 9 kW unit generally suits a medium to large home, or an older property of moderate size where insulation is weaker and heat loss consequently higher, with a calculated heat load between roughly 6 and 9 kW. Floor area alone is not a reliable guide, because insulation quality, glazing, ceiling height, local climate, and hot water demand all affect the load. Note the 3.5 kW minimum modulated output: in a well-insulated property whose mild-weather demand sits near 2 to 3 kW, the unit would cycle rather than modulate, and a smaller model would perform better through most of the season.
Why does the 9 kW use DN25 water connections instead of DN20?
Because of flow rate. The 9 kW unit circulates 1.72 m³/h against 1.38 m³/h on the 6 kW model, and pushing that volume through DN20 pipework would create excessive pressure loss and water velocity. The G1.0 DN25 connection sizes the port to the flow. This matters at design stage: if you are replacing a 6 kW unit or a project capacity may be revised upward, confirm the connection size early, because reducing DN25 back down to DN20 at the unit introduces a restriction exactly where flow matters most. The 16 kW model uses the same DN25 connections.
Is the 9 kW less efficient than the smaller models?
No, and this is slightly counterintuitive. The 9 kW achieves a COP of 4.46 at A7/W35, which is higher than the 6 kW model's 4.42, and close to the 5 kW model's 4.5. All four capacities are inverter-driven units on the same platform, and the larger heat exchanger surface in the 9 kW offsets the greater compressor duty. The practical consequence is that you can size on load and hot water demand without trading capacity against efficiency across this part of the range.
Should I choose the 6 kW or the 9 kW?
Choose the 9 kW if your calculated load sits between roughly 6 and 9 kW, if hot water demand is high, since it produces 10 kW at 215 litres per hour against 8 kW and 172 litres per hour on the 6 kW, or if you need 6.5 kW of cooling rather than 5 kW. It also fits the same cabinet dimensions as the 6 kW, so stepping up costs no additional space. Choose the 6 kW if your load is nearer 4 to 7 kW, because its 3.0 kW minimum modulates slightly better in mild weather, and because it uses DN20 pipework which may match an existing installation.
How much hot water does it produce?
The 9 kW unit delivers 10 kW of domestic hot water heating capacity at 215 litres per hour, with a COP of 4.32 and an input power of 2.31 kW. That is roughly 25% more than the 6 kW model and 67% more than the 5 kW, which makes it appropriate for larger families or properties with several bathrooms in simultaneous use. Actual delivery depends on cylinder size, incoming cold water temperature, and target storage temperature, so confirm the full hot water arrangement with your installer.
Can it provide cooling as well as heating?
Yes. The unit is reversible and delivers 6.5 kW of cooling capacity at A35/W7 conditions with an EER of 2.85, running the same refrigeration cycle in the opposite direction. That is enough cooling for a medium to large home from the same equipment that heats it. If the system feeds underfloor heating, note that radiant cooling requires attention to condensation risk, since surfaces cooled below the dew point attract moisture. This is manageable with correct control but belongs in the system design rather than added afterwards.
How noisy is the 9 kW heat pump?
The 9 kW unit is rated at ≤55 dB(A), just one decibel above the 6 kW model despite delivering 50% more output, using a single low-noise axial fan with a brushless DC motor. Placement matters more than the rating alone: position the unit away from bedroom windows and avoid siting it in a corner where sound reflects off two surfaces. The DC inverter compressor helps here, since modulating output produces steadier sound than a fixed-speed unit repeatedly starting and stopping.
Will it work in a cold climate?
The unit is engineered to keep operating down to -35°C ambient, which covers the great majority of populated cold-climate regions. Output does decrease as temperature falls, which applies to every air source heat pump, so cold-climate projects should be sized against the local design temperature rather than the nominal rating. The intelligent demand-based defrost system matters here too, since frequent ineffective defrost cycles are what typically undermines cold-weather comfort in simpler units.
Why R32 rather than R410A?
R32 has a Global Warming Potential of 675 against R410A's 2088, just 32% of it. Its lower liquid density means a smaller refrigerant charge is needed for the same system, and the greater heat required to evaporate R32 means a smaller mass flow rate per unit and a higher COP. There is also a commercial consequence: high-GWP refrigerants face progressive restriction under the European F-Gas Regulation and equivalent rules elsewhere, which makes equipment charged with them harder and more costly to service over time.
What are the unit dimensions and weight?
The 9 kW unit measures 1075 × 480 × 805 mm (W × D × H) and weighs 80 kg net, with packing dimensions of 1165 × 530 × 925 mm. Notably, these are the same cabinet dimensions as the 6 kW model, so stepping up in capacity costs no additional installation space, only 10 kg in weight. Water connections are G1.0 DN25 with a water yield of 1.72 m³/h and a pressure loss of 25 kPa. No expansion tank is included, unlike the 16 kW unit which includes a 5 litre tank, so allow for one in the system design.
What colours is the 9 kW heat pump available in?
Eleven cabinet finishes are available: white, white grey, grey, black, blue, green, red, yellow, gold, brown, and mocca. This range exists for two reasons. For OEM and private-label partners, cabinet colour is part of brand identity. For residential projects, the outdoor unit is often visible from a garden or terrace, and matching it to the building rather than accepting a default white is a meaningful specification option. Colour is one of the customization parameters available on OEM orders alongside logo, nameplate, and packaging.
Is the 9 kW model available for OEM supply?
Yes. OEM and ODM customization covers cabinet colour across eleven available finishes, logo and nameplate, packaging, and controller and operating parameter configuration for private-label supply. Samples are produced and performance tested against your specification before production commitment, and performance and leak test records are available for production batches. All projects are handled under confidentiality agreement. Contact the technical team with your target market and volumes to discuss terms.
What certification does it carry?
The unit is CE and RoHS certified and carries an ERP energy label rating of A+++ at 35°C and A++ at 55°C. CE confirms compliance with applicable European safety, electromagnetic compatibility, and low voltage requirements, and RoHS confirms restriction of hazardous substances in electronic components. Certification documentation is available on request for regulatory submission and procurement compliance. Confirm any additional market-specific requirements for your destination, since certification obligations depend on where the product is sold rather than where it is manufactured.