HeatTank is our thermal energy solution

HeatTank is the revolution of thermal energy storage systems.

HeatTank in operation, HeatTank is working, Heatventors

How it works

The HeatTank balances the efficiency of the cooling/heating system. It also provides an extra layer of operational safety in case of equipment failure. As its name suggests, HeatTank serves as an energy buffer with independent control logic.

Our competitive advantage: The use of Phase Change Materials instead of water. By melting and solidifying these materials we store thermal energy in a more concentrated way to save space, energy and cost in an environmentally friendly way.


Charging phase

When excess thermal energy is available or can be generated more efficiently we store a part of the generated thermal energy. When we store the cooling energy the Phase Change Material solidifies and when we store the heating energy the Phase Change Material melts.


Store energy

HeatTank stores the thermal energy which was produced during the charging phase.


Discharge phase

When the thermal energy is needed we draw on the pre-stored energy. During the discharge period of the cooling energy the Phase Change Material melts, while for the heat energy, the Phase Change Material solidifies.


HeatTank can be installed in different ways.Depending on the problems that need to be solved

Peak performance management

Safety backup cooling/heating system

Increase the stability of the HVAC systems

Increase the efficiency of the thermal energy systems

It is possible to use the HeatTank for multiple purposes, for example  it can be responsible for peak performance management and increase the efficiency in off-peak periods.

Peak performance management

Usually the design of the cooling system is made for the hottest few summer days. The designers take into account the increase of the outside temperature even in the next 5-10 years. An oversized system equals less efficiency, shorter lifetime and more maintenance costs.

With HeatTank, the cooling system is able to provide the cooling energy in 95% of the year.

Check out our example:

Figure 1 shows that traditionally when the outside temperature is 39 °C and the cooling need is 80 kW, the chosen chiller will be 90 – 100 kW. If we design the system for 95% of the year, the cooling need will be 58,5 kW, which means 37% size reduction compared to the 80 kW system. The system is able to serve the needs in most of the time except for 84 hours (which is divided to 20 days, including 8 weekend days). (It is a typical case in Central Europe.) When there are additional needs, HeatTank will be part of the system and cover the peak needs as an extra cooling energy source.

For peak performance management price-value calculations are required. This purpose is usable where the cooling needs are changing during a day, for example the cooling needs depend on the change of the outside temperature or when the inner heat generation is changing during the day (like in a meeting room). It can also be used for very humid environments, where the peaks are defined by the humidity. The purpose of the HeatTank is to cover the additional needs in peak time.

Safety backup cooling

Safety backup cooling means that the stored thermal energy is usable immediately in case of emergency, when the air-conditioning system needs minutes to get back its maximum cooling performance after a blackout. HeatTank is able to ensure the cooling needs for 15-20 minutes.

Increase the stability of the cooling system

The outdoor item of the cooling system has to turn on and off frequently which will decrease its efficiency and its lifetime. The purpose of the HeatTank is to reduce the starts per hour and reduce the partial load periods.

Increase the efficiency of the cooling system

The 3 possibilities to save energy with HeatTank.

The problem

The cooling systems work with changing efficiency during a day. When the outside temperature is low (usually at night) the efficiency is high, but when the outside temperature is high (usually at midday) the efficiency is low. Which means that when the outside temperature is low we can generate more cooling energy from one unit of electricity than when the outside temperature is high.

1. Free-cooling

The first possibility is free-cooling. When the outside temperature is lower than the inside temperature the cooling potential of the outside air can be used. We use indirect free-cooling with 2 independent heat exchange surfaces, so the moisture and dust do not get in the building.

2. Increasing free-cooling period

The second option is increasing the free-cooling period. When free-cooling is only available during the night or for only a few hours per day, HeatTank can be fully loaded and used when the free-cooling is not possible anymore.

3. Energy Efficiency Ratio

The EER (Energy Efficiency Ratio) of the cooling systems are based on the outside temperature and the air humidity. In case of a lower outside temperature the EER is higher, meaning that the energy consumption could be reduced by generating the cooling energy in the most efficient periods (e.g. at night). HeatTank stores this cooling energy and uses it when the efficiency is lower. Figure 2. shows the real efficiency of a modern chiller, based on measurements.

Further our customers get a balanced energy consumption which is favorable at negotiation with energy suppliers. It is also possible to use the energy tariff difference between peak and off-peak periods (if it is available in your country).

EER in function of outside temperature

As we discussed above the EER depends on the outside temperature and the partial load. On the diagram you can see the frequentness of the outside temperatures in Hungary.

Store waste heat energy

The heat generation and the need for the heat are usually different in time. When you have a solar collector you collect the heat during the day but you will use it during the night. It is the same in the industry. There are several gas engines working in Virtual Power Plant mode, which means that they operate when the whole electricity system has to be controlled, so the electricity generation is more important than the heat generation which is fluctuating and different in time than the needs of the heat. In this cases we have to store the heat as a thermal battery.

The control system and energy report

With our control system HeatTank always works at an optimal level as we can control the charging and discharging periods, to gain even higher energy savings. In additio,n we offer energy reports to our clients regarding the operation of their energy systems and the quantity of the saved electricity.

Get an offer

Parts of the HeatTank

The 3 possibilities to save energy with HeatTank.

HeatTank controller panel, processor


HeatTank has its own controller unit. It contains the hardware and the software as well. This controller's main task is to work on optimization of the cooling from 30 facts. It is patented.


HeatTank has its own designed tank. The tank’s design and structure is patented. Its capacity and performance is great and it comes in a small size. We have an experienced and recognized manufacturer partner.

HeatTank patended design
phase changing material of the HeatTank

Phase Change Material

There are several phase change materials that we use. We decided to use these materials after many years of research. These are completely harmless for the environment and for humanity. Their lifetime is about 30 years, if we calculate with one phase change per day. We have several suppliers who can ensure the material supply.

HeatTank Size


HeatTank 25-1

HeatTank 25-2

HeatTank 50-1

HeatTank 50-2

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Let's work together

Usually it takes 8-10 weeks from assessment to installation.

2 weeks

Assessment & Design

We make assessment on your cooling system and design a unique HeatTank system for you after we discussed which possibility is the most important in your case (saving energy, increase safety etc.).



You get an offer, when you are pleased with the calculations, which is personalized for your unique system.

4-6 weeks


We manufacture and deliver your tank with the phase change material together and buy your system items (thermoventillator, pump etc.).

1 week

Installation & Optimization

After delivery the HeatTank is ready for installing. As you would like, our or your maintanance staff install it and we optimize the operation for your cooling system.

Energy reports

After the installation and optimization we can provide monthly energy reports on the quantity of saved electricity.