What is a CO₂ heat pump and when should one choose it?

Why use CO₂ as a refrigerant in heat pumps?

With increasingly strict environmental regulations and higher taxes, the market for refrigeration systems and heat pumps is being steered towards natural refrigerants that do not contribute to direct global warming. CO₂ has a GWP (Global Warming Potential) of 1 and does not break down into PFAS. Therefore, Tequs has chosen CO₂ (R744), which is neither toxic nor flammable.

The properties of CO₂ make it an ideal refrigerant for heat pumps where high temperatures are needed, but it is also preferred in many other applications. New technology has made CO₂ a particularly energy- and cost-efficient alternative. The high system pressure allows for smaller physical dimensions and lesser filling quantities than the traditional HFC (Hydrofluorocarbon) refrigerants.

Natural and environmental friendly refrigerants like Propane (flammable) and ammonia (toxic and panic-inducing) have many good properties, but often require their own safety measures, which are not included in the economic calculations when choosing a solution 

How does a CO₂ heat pump work?

At low pressures and temperatures on the warm side, a CO₂ heat pump functions just like any other heat pump, which is known as subcritical operation. When the temperature entering the heat exchanger exceeds 20-25°C, the pressure becomes so high that CO₂ no longer condenses; this is called transcritical operation. Instead of condensing the CO₂ gas, we cool it down.

This transcritical operation provides an advantage in terms of heating water/liquid since the temperature curves of the water and the CO₂ gas follow each other.

This allows for achieving very high temperatures from the heat pump in an energy-efficient manner. This is one of the main reasons to why CO₂ heat pumps are generally more energy-efficient than other heat pumps at high temperatures, such as in applications with a large demand for domestic hot water.

When should one choose a CO₂ heat pump from Tequs?

The TCHP series is not like other CO₂ heat pumps. They are physically smaller (can pass through all doors), much more flexible in use, pre-configured, and pre-filled. These can handle different temperatures than what is normal for CO₂ heat pumps. The products we have developed represent the next generation of CO₂ machines with ejector operation at all performances. The machines are designed with the most modern technical principles and built only with the best components from well-recognized brand names. Despite the compact design, the machine is service-friendly.

The TCHP series are easy to plan with, and Tequs is happy to contribute with solutions. Often, the biggest limitation for CO₂ is the return temperature, but Tequs has solutions that can handle return temperatures up to 50°C directly in the heat pump.

This means that they are suitable for a much wider range of applications than what is usually achieved with a CO₂ heat pump, such as low-temperature space heating and high-temperature space heating (47/55°C) and domestic hot water.

Tequs's units are particularly well-suited where there are requirements for high, low, or multiple simultaneous temperature levels, such as:

·     Replacing older radiator systems

·     Swimming pools and sports facilities

·     Hospitals and schools

·     Hotels

·     Domestic hot water

·     Comfort heating and cooling

·     Data centers and server farms

·     District and local heating

·     Fish farming and aquaculture

·     Industrial applications

·     Car wash facilities 

By combining the needs for cooling and heating, many exciting possibilities arise. Our technology has pushed the boundaries of what can be expected in handling supply and return temperatures, up to around 60°C when combined with our hydronic kit.