The Mixergy 150L R290 iHP (MX-150-IH2-579) is a smart unvented hot water cylinder with a factory-fitted, integrated air-to-water heat pump — part of the Mixergy iHP X R290 range. There is no separate outdoor unit: the compact heat pump head sits on top of the cylinder indoors, connected to outside air through 150mm ducting, making it well suited to apartments, high-rise developments and all-electric new-build homes where an external ASHP is impractical.
Using Mixergy's patented top-down stratified heating, the cylinder delivers usable hot water in under 30 minutes from cold — up to 10x faster than conventional integrated heat pump cylinders that must heat the full volume before any water is usable. The system runs roughly three times more efficiently than a direct electric cylinder and connects to the Mixergy app for machine-learning schedules, time-of-use tariff optimisation and live hot water level monitoring.
<30 min
To usable hot water
Qualified Installer Required
This is an unvented hot water system with an integrated heat pump. Installation, commissioning and servicing must be carried out by an installer qualified to G3 standard. Incoming mains pressure must be below 10 bar with a minimum flow rate of 10 L/min, and the supplied pressure reducing valve, temperature & pressure relief valve (set at 7 bar / 90°C) and tundish must be fitted and discharge-tested in line with Building Regulations Part G3. The cylinder must be installed on a floor able to support its full weight of approximately 236kg.
Dedicated Electrical Supply
The heat pump head requires its own 16A MCB-protected, 13A double-pole fused spur supply — do not share this circuit with other loads. The cylinder must be registered and connected to the internet via the supplied Ethernet-to-powerline adapter (or hard-wired Ethernet) to validate the 25-year manufacturer warranty.
Top-Down Advantage
Because Mixergy's patented stratification heats from the top down, hot water reaches the tap in under 30 minutes even from a fully cold 150L cylinder — conventional heat pump cylinders must bring the entire volume up to temperature before any hot water is available.
Integrated R290 Heat Pump
A compact air-to-water heat pump is factory-fitted directly onto the cylinder head, so there's no outdoor unit, no refrigerant pipework and no F-Gas certification needed for installation — only 150mm air ducting to the outside.
Patented Top-Down Heating
Mixergy's stratified heating technology fills the cylinder from the top down, so usable hot water is available in under 30 minutes, rather than waiting for the full tank to reach temperature.
Smart App Control
The Mixergy app uses machine learning to predict hot water demand, schedule heating around low-carbon or off-peak tariffs, and shows a live hot water charge level — helping cut running costs without manual scheduling.
Removable Head Unit
The heat pump head is a separate, removable module from the cylinder body, simplifying transport, installation into tight spaces, and future servicing or replacement without disturbing the cylinder.
Low-Cost SAP Compliance
The iHP X range is recognised in SAP and RdSAP calculations, helping developers hit EPC targets on all-electric and Future Homes Standard-aligned developments without needing an external heat pump.
Duplex Stainless Steel Cylinder
The cylinder body is manufactured from Duplex stainless steel, backed by a 25-year warranty, with a 5-year warranty on the heat pump head unit.
| Model & Capacity |
| Product code |
MX-150-IH2-579 |
| Nominal capacity |
150 litres |
| Height |
1,515mm |
| Diameter |
580mm |
| Weight empty |
86kg |
| Weight full |
236kg |
| Cylinder material |
Duplex stainless steel |
| Heat Pump Performance |
| Refrigerant |
R290 (propane), GWP of 3, zero ODP |
| Air operating range |
-7°C to +35°C |
| Achievable hot water temperature (heat pump) |
Up to 59°C |
| Heat pump electrical rating |
0.55 kW |
| Heat pump max. power output |
1.5 kW |
| Coefficient of Performance (CoP) |
Approx. 3.4 (manufacturer-stated test conditions) |
| Standing heat loss |
0.54–1.22 kWh/24hr |
| Air, Water & Electrical |
| Sound power |
50 dB |
| Airflow |
500 m³/hr |
| Air duct diameter |
150mm (160mm with supplied adaptors) |
| Water connections |
22mm compression |
| Electrical supply |
13A, 230–240V~, dedicated circuit |
| Back-up immersion heater |
2kW immersion, thermal cut-out fitted |
| Warranty |
| Cylinder & heat pump head |
25 years on the cylinder, 5 years on the heat pump head |
Mixergy iHP X R290 Range — Capacity Comparison
| Capacity |
Product Code |
Height |
Diameter |
Weight (full) |
| 120L |
MX-120-IH2-579 |
1,325mm |
580mm |
203kg |
| 150L |
MX-150-IH2-579 |
1,515mm |
580mm |
236kg |
| 180L |
MX-180-IH2-579 |
1,695mm |
580mm |
270kg |
| 210L |
MX-210-IH2-579 |
1,885mm |
580mm |
304kg |
| 250L |
MX-250-IH2-579 |
2,145mm |
580mm |
347kg |
Does the iHP need an outdoor heat pump unit?
No. The R290 heat pump is fully integrated into the cylinder head indoors. Only 150mm air ducts to the outside are required — there's no outdoor unit and no refrigerant pipework installation.
How fast does it deliver hot water?
The 150L iHP uses Mixergy's patented top-down stratified heating to deliver usable hot water in under 30 minutes from cold, even though the full cylinder volume takes longer to reach temperature.
What electrical supply does it need?
A dedicated 13A, 230–240V supply protected by a 16A MCB, plus a fused spur for the heat pump head. The 2kW back-up immersion heater uses the same electrical connection.
Does it need an internet connection?
Yes. The cylinder must be connected to the internet — via the supplied Ethernet-to-powerline adapter or hard-wired Ethernet — to enable app control, machine-learning scheduling and to validate the 25-year cylinder warranty.
Who can install this cylinder?
This is an unvented system with an integrated heat pump, so installation, commissioning and servicing must be carried out by an installer qualified to G3 standard, following Mixergy's installation and servicing instructions.
What's the difference between the 150L and other capacities in the range?
All iHP X R290 models share the same 580mm diameter, heat pump head, CoP and controls. Only the cylinder height, weight and standing heat loss increase with capacity — see the capacity comparison table above.
