An R290 air to water heat pump extracts heat from outdoor air and transfers it to water for space heating, domestic hot water and, with a suitable system, cooling. EXINDA supplies R290 monoblock systems for European houses, residential retrofits, multi-family buildings and selected light-commercial projects through distributors and regional partners.
The right product cannot be selected from nominal kilowatts alone. Building heat loss, winter design temperature, required water temperature, emitters, domestic-hot-water demand, electricity supply and the exact model’s certified performance all affect the result.
This guide explains the product category, EXINDA range, common applications, selection process, European documentation and support available to distributors, installers and project teams.
What Is an R290 Air to Water Heat Pump?
An R290 air-to-water heat pump is an electrically driven heating appliance that uses propane, designated R290, as its refrigerant. The refrigeration circuit absorbs energy from outdoor air and raises its temperature. A heat exchanger then transfers that energy to the building’s water circuit.
Depending on the selected model and system design, the heated or cooled water can serve:
- Radiators
- Underfloor heating
- Fan-coil units
- Buffer tanks
- Domestic-hot-water cylinders
- Multiple hydronic zones
- Cascade systems for larger loads
Unlike an air-to-air heat pump, an air-to-water system delivers energy to a water circuit rather than blowing conditioned air directly into rooms. It is therefore relevant to buildings that already use a boiler and radiators, as well as new hydronic heating systems.
Why Is R290 Used in Air-to-Water Heat Pumps?
R290 is propane, a natural refrigerant with very low global-warming impact compared with many conventional fluorinated refrigerants. It also has thermodynamic properties that can support efficient heating and higher leaving-water temperatures when the equipment is engineered for those duties.
For buyers, the refrigerant alone does not prove that a heat pump is efficient, quiet or suitable for a project. The complete design matters, including the compressor, heat exchangers, controls, refrigerant charge, acoustic design, defrost strategy and certified performance at the required operating condition.
R290 is flammable. Equipment placement, clearances, drainage, handling, service work and local compliance must follow the current model-specific manual and applicable national rules. A monoblock design keeps the factory-sealed refrigerant circuit within the outdoor unit, while water connections run into the building.
What Can an R290 Air to Water Heat Pump Provide?
| Function | Typical system connection | Main design question |
|---|---|---|
| Space heating | Radiators, underfloor loops or fan coils | Can the unit meet heat loss at design conditions? |
| Domestic hot water | Indirect hot-water cylinder | What storage volume and recovery rate are required? |
| Space cooling | Fan coils or suitable radiant system | How will condensation and humidity be controlled? |
| Boiler replacement | Existing hydronic pipework and emitters | What water temperature and radiator output are needed? |
| Multi-family heating | Central plant, cascade or mixed architecture | How will loads, zoning and redundancy be managed? |
A single unit may support more than one function, but the system must establish priorities. Domestic-hot-water production, for example, usually requires a different water temperature and control sequence from space heating.
EXINDA R290 Air-to-Water Heat Pump Range
EXINDA’s public European residential collection currently presents R290 monoblock models in nominal 6, 9, 12, 15 and 20 kW classes. Available capacity, voltage, controller functions, operating envelope, sound data and certification scope must be confirmed against the exact model and current technical submittal.
View the EXINDA residential R290 air-to-water heat pump range.
| Nominal class | Typical project context | Selection warning |
| 6 kW | Smaller or efficient homes and individual apartments | Verify output at winter design temperature |
| 9 kW | Low-to-medium residential heat loads | Do not select from floor area alone |
| 12 kW | Medium residential projects and retrofits | Check required radiator water temperature |
| 15 kW | Larger homes and higher-load residential projects | Confirm electrical supply and minimum modulation |
| 20 kW | Large houses, multi-residential zones or staged systems | Review hydraulic design and cascade strategy |
These descriptions are application starting points, not sizing rules. A 12 kW label does not mean the unit supplies 12 kW at every combination of outdoor and leaving-water temperature.
Installers and distributors can also review the EXINDA R290 heat pump manufacturer and supplier page for the broader European product and support proposition.
How Should an R290 Air to Water Heat Pump Be Selected?
Selection should begin with the building and operating condition, then move to the product.
1. Establish the design heat loss
Use a room-by-room or building heat-loss calculation based on the local winter design temperature. Floor area is useful context, but it cannot capture insulation, airtightness, glazing, exposure or ventilation losses accurately enough for final selection.
2. Identify the required leaving-water temperature
Underfloor heating often operates at lower water temperatures than existing radiators. Higher water temperature generally makes a heat pump work harder and may reduce capacity and efficiency. Determine the water temperature needed to deliver the room heat load before selecting the model.
3. Check capacity at the real operating point
Compare published heating output at an outdoor and water condition close to the project requirement. A7/W35 data describe operation at 7°C outdoor air and 35°C leaving water; they should not be treated as proof of performance at −7°C outdoor air and 55°C water.
4. Review modulation and part-load operation
Oversizing may create short cycling in milder weather. Check minimum output, system water volume, zoning and control strategy as well as maximum capacity.
5. Confirm the electrical and hydraulic requirements
Verify single- or three-phase supply, maximum current, backup-heater requirements, minimum water flow, system pressure drop, pipe sizes, circulation pumps and freeze protection.
6. Check noise and placement
Review sound power or sound pressure using the stated test condition. Site geometry, reflective walls, windows, neighbouring properties and night operation can affect the acceptable location.
Can an R290 Air to Water Heat Pump Replace a Boiler?
Yes, subject to a proper building and hydronic assessment. An R290 unit can replace or reduce reliance on a gas or oil boiler while retaining suitable parts of the water-based distribution system.
Before a boiler replacement, the project team should check:
- Building heat loss at local design temperature
- Heat-pump output at the required water temperature
- Radiator or underfloor-heating output
- Existing pipe sizes and available water flow
- Hydraulic balancing and zone controls
- Domestic-hot-water cylinder compatibility
- Electrical capacity
- Freeze protection and defrost drainage
- Need for supplementary or backup heat
The EXINDA boiler-to-R290 heat pump retrofit case shows a UK residential system integrated with an existing radiator loop, control module and domestic-hot-water arrangement.
Can It Work With Existing Radiators?
An R290 air-to-water heat pump can work with radiators if those emitters deliver enough heat at the proposed flow and return temperatures. A radiator rated for a boiler system may provide substantially less output when its mean water temperature is reduced.
The assessment should compare each room’s heat loss with its radiator output at the intended heat-pump condition. Possible improvements include:
- Enlarging selected radiators
- Installing low-temperature radiators or fan-assisted emitters
- Improving insulation and airtightness
- Rebalancing the hydronic circuit
- Reducing unnecessary flow-temperature setpoints
- Applying weather-compensated control
- EXINDA’s German luxury-villa heat pump installation provides a related example involving a radiator-based hydronic system, domestic-hot-water storage and weather-compensated controls.
What Does “High Temperature” Mean for an R290 Heat Pump?
High-temperature capability refers to the leaving-water temperature the heat pump can produce within a defined operating envelope. EXINDA’s current public Storm Series page states water temperatures up to 75°C; this is a maximum product capability rather than a recommended year-round design temperature and must be checked for the selected model and outdoor condition.
Operating at the lowest water temperature that still satisfies comfort normally supports better efficiency. A project should not specify 70–75°C simply because it is available. Instead, determine the temperature required at the design condition and use weather compensation to reduce it when outdoor conditions are milder.
View the EXINDA residential R290 inverter air-to-water heat pump product page.
Is It Suitable for Underfloor Heating?
Yes. Underfloor heating is a common match for an air-to-water heat pump because its large emitter area can often meet the building load with relatively low water temperatures.
System design still needs to address:
- Floor heat-output limits
- Pipe spacing and loop lengths
- Manifold balancing
- Minimum water flow
- Mixing controls, if different temperature circuits coexist
- Floor-finish temperature limits
- Zoning and actuator behaviour
- Thermal response time
Combining underfloor heating and radiators may require separate temperature zones or hydraulic arrangements.
Can It Produce Domestic Hot Water?
Yes. A compatible indirect cylinder, sensor and control sequence allow the heat pump to produce domestic hot water. The designer should establish storage volume, target temperature, reheating time, peak demand and any hygiene cycle or supplementary heater required by the project.
In Italy, two EXINDA 22 kW R290 air-to-water units have been applied to centralized domestic-hot-water production for a 20-home residential complex. Read the Italian domestic-hot-water case study.
Can R290 Heat Pumps Serve Multi-Family Buildings?
Yes. Multi-family projects may use a centralized system, individual units or a combined arrangement. The design must address simultaneous demand, hydraulic zoning, redundancy, domestic hot water, metering, plant access and control ownership.
An EXINDA project in Italy used a mix of centralized cascade and decentralized R290 systems for heating, cooling and domestic hot water. View the multi-residential R290 project in Italy.
For larger loads, multiple heat pumps can be staged when the applicable models and controller support cascade operation. Cascade design should consider part-load efficiency, minimum flow, buffer volume, sequencing, fault resilience and peak-load strategy.
Monoblock System: What Must Installers Consider?
In a monoblock heat pump, the refrigeration circuit is assembled and sealed within the outdoor unit. The installer connects the building’s water circuit and electrical/control services.
Important installation topics include:
- Outdoor-unit safety clearances
- Stable base and vibration control
- Unrestricted air intake and discharge
- Service access
- Condensate and defrost-water drainage
- Protection of external water pipework
- Freeze protection during power failure
- Adequate water volume and minimum flow
- Dirt separation, strainers and water quality
- Air removal and system pressure
- Electrical protection and isolation
- Sensor positions and controller setup
Because R290 is flammable, installers must use the model-specific installation instructions and comply with applicable local requirements. Refrigeration-circuit work should be limited to appropriately qualified personnel.
What European Documents Should Buyers Request?
Documentation should match the exact model, capacity and electrical configuration being purchased.
| Document or evidence | What the buyer should verify |
| CE documentation | Exact model identification and applicable conformity documents |
| ErP information | Product fiche, label and seasonal data for the selected configuration |
| Heat Pump KEYMARK | Model and capacity included within the certificate scope |
| MCS listing | Exact UK-market product and current listing status where required |
| EN 14511 data | Capacity and efficiency at stated rating conditions |
| EN 14825 data | Seasonal performance under the declared climate and application |
| Sound data | Metric, test standard and operating condition |
| Technical submittal | Operating envelope, flow, electrical and dimensional data |
Heat Pump KEYMARK and MCS are not blanket claims for every EXINDA unit. Confirm status for the exact model before using it in a tender, subsidy application or customer quotation. UK project teams can read the MCS-certified R290 heat pump guide for boiler retrofits.
Which Performance Data Matter Most?
Buyers should compare model-specific data, not only the headline COP.
- Heating capacity at design outdoor temperature
- Capacity at the required leaving-water temperature
- COP at clearly stated conditions
- SCOP and declared climate
- Minimum and maximum compressor output
- Water-flow requirements
- Maximum electrical input and current
- Backup-heater capacity and control
- Operating envelope
- Sound power and stated acoustic mode
- Defrost behaviour
- Domestic-hot-water operating range
For a deeper engineering comparison, see the EXINDA R290 monoblock technical-difference article.
How EXINDA Supports European Projects
EXINDA works with distributors, regional agents, heating contractors, installers and project companies. Heat-pump cooperation is based on EXINDA-branded distribution and regional market development rather than private-label heat-pump supply.
| Project stage | Available support |
| Initial enquiry | Product and application discussion |
| Selection | Review of load, climate and water-temperature requirement |
| Technical approval | Model-specific data and available certification documents |
| Installation preparation | Manuals, connection information and controller documents |
| Commissioning | Product-side setup and operating guidance |
| After-sales | Troubleshooting information and spare-parts identification |
| Channel development | Distributor or regional-agent evaluation and training support |
The installer or project designer remains responsible for the complete building and hydronic design, installation quality and local compliance. EXINDA’s role is to provide accurate product-side information and cooperation support based on the project data supplied.
Frequently Asked Questions
What is an R290 air to water heat pump?
An R290 air to water heat pump uses propane refrigerant to extract energy from outdoor air and transfer it to a water circuit for heating, domestic hot water and, with a suitable system, cooling.
Is an R290 heat pump the same as an air source heat pump?
It is a type of air source heat pump. “Air source” describes the energy source; “air to water” specifies that the heat is delivered to a hydronic water system.
Is an R290 air-to-water heat pump suitable for a house?
Yes, when its capacity, water-temperature range, electrical supply and controls match the building heat loss, emitters, climate and domestic-hot-water demand.
Can it replace a gas or oil boiler?
Yes, in suitable projects. The assessment must include building heat loss, radiator output, design water temperature, electrical capacity, hydraulic condition and backup requirements.
Can an R290 heat pump use existing radiators?
Yes, if the radiators provide sufficient room heat at the proposed flow and return temperatures. Some projects require larger radiators or building-fabric improvements.
Can an R290 heat pump reach 75°C water temperature?
EXINDA’s current public Storm Series page states up to 75°C, but the actual available temperature depends on the exact model and operating envelope. Maximum temperature should not be confused with the most efficient normal setpoint.
Does an air-to-water heat pump provide cooling?
Applicable reversible models can produce chilled water for suitable fan coils or other designed cooling emitters. Condensation control and humidity management are essential.
Is a buffer tank always required?
No. The decision depends on minimum system water volume, flow stability, zoning, compressor modulation, defrost needs and hydraulic separation. It should be designed, not added automatically.
Are all EXINDA R290 models Heat Pump KEYMARK certified?
Certification must be checked for the exact model and capacity. A certificate covering selected products must not be treated as approval for the complete range.
What information does EXINDA need for selection?
Provide the project country and city, design heat loss, outdoor design temperature, required flow and return temperatures, emitter type, domestic-hot-water demand, electrical supply, quantity and project schedule.
Can installers buy directly from EXINDA?
Supply depends on the country, quantity and regional distribution structure. EXINDA may serve the project through an authorized distributor or discuss regional cooperation with qualified HVAC companies.
Request R290 Air-to-Water Heat Pump Support
For a project or distribution enquiry, send:
- Company name and country
- Project city and building type
- Calculated design heat loss
- Outdoor design temperature
- Required flow and return temperatures
- Radiator, underfloor-heating or fan-coil details
- Domestic-hot-water requirement
- Electrical supply
- Required capacity and quantity, if already estimated
- Certification or tender-document requirements
- Project schedule
Email: info@exindagroup.com