The SolaX Thermal R290 single-phase air-to-water heat pump is available in 8kW, 10kW, 12kW, 14kW and 16kW sizes. It uses R290 natural refrigerant with a very low GWP of 3, delivers heating, cooling and domestic hot water, and reaches flow temperatures up to 80°C for high-temperature radiator systems and DHW.
Efficiency is strong, with a SCOP of up to 5.44 at 35°C and a SCOP of up to 4.12 at 55°C. Sound pressure levels are low, from 35 dB(A) at 1m. It is PV and battery compatible, SG Ready, supports Modbus TCP/RTU and is controlled through a smart app with OTA updates.
8-16kW
Single-Phase Sizes
R290
GWP 3 Refrigerant
Up to 5.44
SCOP at 35°C
80°C
Max Flow Temperature
From 35 dB(A)
Sound at 1m
A+++
SCOP Level
Important Safety Information
R290 is a flammable natural refrigerant (propane). Installation and commissioning must be carried out by suitably qualified engineers, with electrical work to BS 7671 and Part P, and in line with the manufacturer's guidance on flammable refrigerant handling. For MCS-certified installations follow MCS standards.
Please Note
This page covers the outdoor unit in the single-phase (STU1) version. An indoor unit (Control Unit, Hydraulic Unit or Hydraulic Integrated Unit) is required to complete the system. Three-phase models are a separate range.
About the SCOP Figures
The SCOP values in the table are SolaX's SCOP-LWT ratings. MCS-listed SCOPs are published separately and can differ: for example, the 8kW is MCS-listed at 5.31 at 35°C and 4.01 at 55°C. When designing under MCS, check the MCS product listing for your exact model.
Natural Refrigerant
R290 has a GWP of just 3, supporting a low-carbon heating system.
High Efficiency
SCOP up to 5.44 at 35°C and up to 4.12 at 55°C, rated A+++.
Very Quiet
Sound pressure from 35 dB(A) at 1m and 32 dB(A) at 3m on the 8kW and 10kW models.
High Flow Temperature
Up to 80°C heating, 25 to 70°C DHW and 5 to 25°C cooling water outlet.
PV & Battery Ready
Designed to integrate with solar PV and battery storage to maximise self-consumption.
Smart & Interoperable
Smart app control, OTA updates, SG Ready and Modbus TCP/RTU support.
Model
Nominal Size
SCOP at 35°C
SCOP at 55°C
Refrigerant Charge
Sound at 1m / 3m
Weight
STU1-C08R290
8kW
5.44
4.12
1.2kg
35 / 32 dB(A)
140kg
STU1-C10R290
10kW
5.30
4.07
1.2kg
35 / 32 dB(A)
140kg
STU1-C12R290
12kW
5.07
3.89
1.5kg
37 / 34 dB(A)
154kg
STU1-C14R290
14kW
4.94
3.84
1.5kg
38 / 35 dB(A)
154kg
STU1-C16R290
16kW
4.90
3.83
1.5kg
38 / 35 dB(A)
154kg
Electrical (all models)
Power supply
220 to 240V / 1N~ / 50Hz
Refrigerant type / GWP
R290 / 3
Water Outlet Temperatures (all models)
Heating
25 to 80°C
Cooling
5 to 25°C
Domestic hot water (DHW)
25 to 70°C
Mechanical (all models)
Dimensions (W x H x D)
1310 x 1050 x 465mm
Functions
Heating, cooling, domestic hot water
Compatibility
PV and ESS integration, SG Ready, Modbus TCP/RTU
Control
Smart app with remote monitoring, operation and OTA updates
Motor
Brushless DC with stepless speed regulation
What sizes are covered here?
The 8kW, 10kW, 12kW, 14kW and 16kW single-phase outdoor units, with SCOP, sound level, refrigerant charge and weight compared in the variant table.
Which indoor unit do I need?
The system needs one indoor unit. SolaX offers a wall-mounted Control Unit (STN1-C01) for existing or self-installed hydraulic circuits and hot water tanks, a wall-mounted Hydraulic Unit (STN1-C02) that adds hydraulic components including a 3kW + 6kW backup heater, and a floor-standing Hydraulic Integrated Unit (STN1-C03) with a 190-litre hot water cylinder built in. The right one depends on your existing plumbing and hot water storage.
What refrigerant does it use?
R290 (propane) with a GWP of 3. Charge is 1.2kg on the 8kW and 10kW models and 1.5kg on the 12 to 16kW models.
How hot can the flow temperature go?
Heating outlet temperature reaches 80°C, and domestic hot water outlet is 25 to 70°C.
Can it cool as well as heat?
Yes. Cooling water outlet is 5 to 25°C, and the system provides heating, cooling and domestic hot water.
Is it a single-phase or three-phase supply?
These STU1 models run on a 220 to 240V single-phase supply. The three-phase STU3 models are a separate range.
