Typical air source heat pumps produce a greater output than a small flat or passive home requires. Our Eco Inverter units are the ideal option for maximum efficiency at smaller outputs.

The Eco Inverter system can produce heating, cooling and optionally domestic hot water and was designed specifically for small flats or passive homes that have lower output heating demands. With a scalable heating range between 1kW (min) and 5kW (max) the solution is ideal for flats up to 100m² or passive homes up to 250m².

Incredible efficiency and savings

Installing an air source heat pump is one of the best routes to savings with amazing returns for home and building owners. For every 1kWh of energy consumed the heat pump can produce up to 5kWh of thermal energy. Our heat pumps typically pay for themselves within 3.5 years or even less if you receive government subsidies or a grant for the system. Our air source Eco Inverter range is strictly limited to indoor units compatible with Mitsubishi Power Inverter outdoor units and provide both heating and cooling.

Why Mitsubishi Power Inverter?

Mitsubishi’s Power inverter series is the one of the most established outdoor units for newer homes. For that reason we created two indoor units that can make the Power Inverter an even better investment for homeowners. We offer a hydrobox for heating and cooling as well as a hydrotank which also heats domestic hot water. A TermoPlus indoor unit with a Power Inverter outdoor unit make an unbeatable combination of efficiency and reliability.

Termo Plus Warranty

Guaranteed to last

TermoPlus’s very first heat pump built in 1984 is still fully operational. The minimum life expectancy of all our heat pumps is 25 years and they are covered by a 3+3 year warranty. This means that with a quick check-up every year you are guaranteed 6 years of absolute peace of mind. We’ll support our products for their entire lifetime and guarantee spare part availability. Find out more about the TermoPlus promise.

Termo Plus Made In EU
Termo Plus TUV


Incredible efficiency and savings

With a heaterless design there is no power requirement for an electric heater. You will enjoy the same comfort without a heating element which would use more energy. The TermoPlus – Mitsubishi combination with energy efficient Eco Inverter technology delivers significant efficiency and unmatched real savings. The use of inverter regulation allows the system to operate at various output levels as opposed to switching between on/off using a standard heat pump.

Flexible and compatible

The combination is suitable for floor, radiator and fan coil heating or cooling in passive buildings or small flats. The system can replace or supplement existing heating systems as it can also work in conjunction with an external heat source such as a biomass, a boiler or a woodstove.

Optimized performance

Performance is boosted in our indoor units but not at the expense of compatibility – the original Mitsubishi weather compensated control is retained along with all features (see in detail below*). Switching between water and space heating is automatic and adequate capacity is ensured so that a storage tank is not required.

Constant availability

You will have uninterrupted hot water up to 55°C with our hydrotank as it uses a large-surface heat exchanger that  heats water up faster due to its larger heat transfer surface.

All-season use

With both heating and cooling the heat pump can cover all-year-round requirements of passive homes and small flats. The outdoor unit can function at temperatures as low as -15°c.

eco inverter air source hydrobox

Function-packed but easy to use

A multi-functional controller provides optimal management with programmes such as automatic anti- legionella, floor drying, holiday mode and a weekly timer.  Web control via app is optionally available and includes an efficiency monitoring feature. Two-zone heating is also available as an option.

Reliable and durable

TermoPlus units can operate  longer than others in harsher conditions due to their larger condenser and the Mitsubishi outdoor units have a proven record of reliability in tough conditions.

Long lasting and easy to maintain

Maintenance is easy to perform since all components are easily accessible. TermoPlus hydrotanks also feature complete anti-corrosion protection through the use of a top quality enamelled water tank with a build-in MG anode.

Quiet and unobtrusive

Both the indoor and outdoor units are both extremely quiet and compact. Using a TermoPlus 120lt domestic hot water tank (DHW) along with the hydrobox also saves space with both units taking up less than 0.5m² of space

All original Mitsubishi control features are retained: Auto-defrost, automatic switching between DHW and heating / cooling, automatic anti-legionella program, control of external heating source , DHW and heating timers *, 2 zone control *, floor dry function*, monitoring of consumed and produced energy (COP)* , access via web and mobile app* , master for cascade connection*   (Features followed by * are optional)


eco inverter air source hydrotank

Domestic Hot Water Hydrotank

The hydrobox can be replaced by a 300l hydrotank that gives you the ability to heat domestic hot water using the system. Alternatively a 120l or 150l DHW tank can be added to the hydrobox and take up very little space.

Optional Electric Heater

This upgrade is unnecessary for most users and allows the use of an electric heater to produce vast quantities of hot water for constant, intense use of temperatures of 70° and higher as well as where a backup may be needed.

Optional web control via app

The original Mitsubishi app allows you to measure the system’s efficiency (COP Monitoring) and to control the system and programs (holiday mode, floor drying etc) from PCs, tablets and smartphones.

Optional Wireless Thermostat

With the optional wireless thermostat you can manage your heat pump with greater control and make adjustments remotely.

Air Source Heat Pumps Web Control



Model & RangeCirculation PumpExpansion VesselDHW TankPipe connection for waterDimensions

(H x W x D or H x diam) (mm)

TermoPlus Hydrobox MZ+25/1-728mm820 x 500 x 350
TermoPlus Hydrotank MZ+ (addon)25/1-7300L28mm1710 x ф750


Mitsubishi ModelEnergy
































(H x W x D) (mm)



Your savings depend on many factors such as your local fuel cost, how much heating you require and what other systems are in place. Let’s consider a small apartment of 60m² using liquid natural gas for heating 5 months a year at a monthly cost of €250 and €40 monthly for domestic hot water (DHW) all year round (totalling €1.730). Installing a passive heat pump with DHW tank would reduce the monthly cost of heating to €40 and of hot water to €8. That would be an annual saving of €1434 which over the 25 year life of the product would amount to €35.850 and that isn’t even taking into account the potential rise of natural gas costs. This real example achieved payback in less than 3 years with a 33% annual return on the investment.

Our air source and domestic hot water heat pumps are extremely easy to maintain and have very low maintenance costs. Our units only require a single annual quick service where we ensure everything is working correctly and efficiently.

The Eco Inverter solution can work in small new buildings and flats, passive homes and some older small flats depending on the quality of insulation and other factors. For older buildings you will most likely need to consider our air-source heat pump range. The units can work with underfloor heating, radiators and fan coils alike. The hydrotank can replace or upgrade existing hot water facilities.