All about enthalpy exchangers
What is an enthalpy exchanger?
Anyone who looks into heat exchangers quickly notices that another term is often used in this context: Enthalpy exchanger (ERV). But what exactly does enthalpy mean? And what is the difference between a heat exchanger and an enthalpy exchanger? Here we explain what enthalpy is all about, how enthalpy exchangers work and where they make sense.
What is meant by enthalpy?
In physical terms, enthalpy is a thermodynamic function that describes the amount of energy in a system. At first, this sounds just as complicated as the term itself. But what is meant by enthalpy is actually pretty simple. In short, enthalpy refers to the heat content of a thermodynamic system. An example for such a system would be a piece of ice floating on water. Or a certain amount of water in a glass. Or the indoor air in your home or your office. So, in the broadest sense, enthalpy refers to the heat that your air contains.
What is the difference between a heat exchanger and an enthalpy exchanger?
This explanation of enthalpy now raises the question of the difference between heat exchangers and enthalpy exchangers – if enthalpy is nothing other than the heat content of the air-moisture-mixture in the indoor air. Generally, an enthalpy exchanger fulfills the same function as a heat exchanger. It transfers the heat of the exhaust air to the supply air or vice versa. But enthalpy exchangers also transfer something else – moisture.
To understand this jump from heat content to moisture exchange, it is necessary to know the relationship between heat and humidity. Warm air – that is air with more heat content – can absorb more moisture. This moisture and the heat it contains is transferred from one airflow to another in heat exchangers with a membrane.
They are referred to as enthalpy heat exchangers to emphasize that they not only transfer sensible heat, which causes a change in temperature, but also additional energy, so-called latent heat. In this way, enthalpy exchangers not only ensure efficient and resource-saving heating or cooling, but they also keep humidity constant.
Why enthalpy exchangers can make sense – effects of low humidity
With their ability to maintain humidity indoors, enthalpy exchangers can contribute to better air and increase people’s well-being. People’s health can be affected if the level of humidity is too low. The most common effects include dry and irritated mucous membranes, irritated airways, dry and burning eyes, and a scratchy throat. But headaches, tiredness and concentration problems can also be the effects of low humidity. People especially struggle with these symptoms in the wintertime. The cold air from outside barely contains any moisture and especially the heated air indoors is dry. In addition to the health problems already mentioned, low humidity also makes the temperature in the house feel colder than it actually is. As a result, you heat more and thus increase your energy costs. This makes it even more important to maintain humidity indoors and to not lose moisture during ventilation or with the exhaust air. Enthalpy exchangers can help with just that.
How enthalpy exchangers work
In terms of functionality, basic design, and flow principle, enthalpy exchangers are very similar to heat exchangers. They similarly transfer heat from one airflow to another – but also moisture. However, this requires a special membrane in an enthalpy exchanger. This membrane separates the supply air from the exhaust air. What’s special is that the membrane is permeable to moisture, but not to air pollutants like viruses, bacteria, or mold spores. Contaminants are also intercepted. When warm air is discharged, its moisture accumulates as water vapor on the membrane. Thanks to the special polymer membrane, the water vapor can be transferred through the membrane to the fresh air side. There, the vapor is once again absorbed by the airflow and returned into the building. Viruses and bacteria, however, stay on the exhaust air side. This ensures that contaminants cannot get back inside. The membrane and its permeability are therefore crucial for the functioning of enthalpy exchangers.
Enthalpy refers to the heat content of a thermodynamic system. An example for such a system would be a piece of ice floating on water. Or a certain amount of water in a glass. Or the indoor air in your home or your office. So, in the broadest sense, enthalpy refers to the heat that your air contains.
Generally, an enthalpy exchanger (ERV) fulfills the same function as a heat exchanger (HRV). It transfers the heat of the exhaust air to the supply air or vice versa. But enthalpy exchangers also transfer something else – moisture.
To understand this jump from heat content to moisture exchange, it is necessary to know the relationship between heat and humidity. Warm air – that is air with more heat content – can absorb more moisture. This moisture and the heat it contains is transferred from one airflow to another in heat exchangers with a membrane.
They are referred to as enthalpy heat exchangers to emphasize that they not only transfer sensible heat, which causes a change in temperature, but also additional energy, so-called latent heat. In this way, enthalpy exchangers not only ensure efficient and resource-saving heating or cooling, but they also keep humidity constant.
With their ability to maintain humidity indoors, enthalpy exchangers can contribute to better air and increase people’s well-being. People’s health can be affected if the level of humidity is too low. The most common effects include dry and irritated mucous membranes, irritated airways, dry and burning eyes, and a scratchy throat. But headaches, tiredness and concentration problems can also be the effects of low humidity.
People especially struggle with these symptoms in the wintertime. The cold air from outside barely contains any moisture and especially the heated air indoors is dry. In addition to the health problems already mentioned, low humidity also makes the temperature in the house feel colder than it actually is. As a result, you heat more and thus increase your energy costs. This makes it even more important to maintain humidity indoors and to not lose moisture during ventilation or with the exhaust air. Enthalpy exchangers can help with just that.
In terms of functionality, basic design, and flow principle, enthalpy exchangers are very similar to heat exchangers. They similarly transfer heat from one airflow to another – but also moisture. However, this requires a special membrane in an enthalpy exchanger. This membrane separates the supply air from the exhaust air.
What’s special is that the membrane is permeable to moisture, but not to air pollutants like viruses, bacteria, or mold spores. Contaminants are also intercepted. When warm air is discharged, its moisture accumulates as water vapor on the membrane. Thanks to the special polymer membrane, the water vapor can be transferred through the membrane to the fresh air side. There, the vapor is once again absorbed by the airflow and returned into the building. Viruses and bacteria, however, stay on the exhaust air side. This ensures that contaminants cannot get back inside.
The membrane and its permeability are therefore crucial for the functioning of enthalpy exchangers.
Why you can rely on CORE enthalpy exchangers
Our enthalpy exchangers (ERVs) are equipped with patented CORE technology. It is based on 30 years of experience in the development of enthalpy exchangers and ensures that moisture is transferred in addition to heat. This reduces year-round fluctuations in indoor humidity. Moreover the integrated membrane blocks air pollutants such as viruses, bacteria or mould spores from entering the air. This allows you to enjoy healthy indoor air and protect the environment at the same time.
To make sure that every enthalpy exchanger fulfills our promise of quality and performance, we check each one for leaks before delivery. You can therefore be sure that your ventilation system will always deliver the best possible performance.
Additional topics
Counterflow heat exchanger vs. crossflow heat exchanger
What are the different types of heat exchangers? How do they work? And when is which technology suitable? We’ll explain all about the different types of heat exchangers.
The membrane in enthalpy exchangers
What is a membrane? And what role does it play in an enthalpy exchanger? We explain what a membrane is and how it enables the transfer of moisture.
Products and solutions
Wide variety of products, patented technology: With our wide-ranging portfolio of crossflow and counterflow heat exchangers, you will always find the right product for your application. And if needed, we can individually manufacture the right heat exchanger for your specific ventilation system.