Exhaust Air Heat Pump

Ventilation systems let warm air out of a building. Exhaust air heat pumps pick up the warm air, and heat fresh air coming into the building, or even heat water. Exhaust air heat pumps can be used to heat water, and heat houses or apartments. They work in the same way as air and ground source heat pumps. Exhaust air heat pumps are often used in underfloor heating systems. They have been used in Germany and Sweden, where they are most prevalent.

What Is Exhaust Air

Air inside a building that needs to be eliminated is called exhaust air. Ventilation systems in buildings must have exhaust fans that work to get rid of bad air from places where it is likely to build up. Bathroom extractor fans keep moisture from building up and causing mould. Kitchen extractor hoods get rid of cooking smoke, odours, and air that the cooking process has not appropriately oxygenated.

How Do Exhaust Heat Pumps Work

Vents in bathrooms, kitchens, and laundry rooms are places where you do not want air to come in. You can use an exhaust air heat pump to take in air through these vents and heat it. Air can be let out only, or let in to be heated or cooled down.

Houses with outside air-diffusers circulate air around the house. Air is moved from rooms with outside air diffusers, to rooms with exhaust air diffusers which move air around the house. If your home has a heater, heat comes from heated air.

The air moves from rooms with supply air diffusers to rooms with exhaust air diffusers, which circulate the air all over the house.

Old air that has been inside the house for a while is heated as it leaves, and sent to the heat pump’s refrigerant circuit. This makes the air cooler. As soon as it is cooled down, it is eliminated. The heat pump’s vapour compression cycle makes the refrigerant hotter and moves the heat into a water system that can heat either the water in your home, or both the water in your home and the building as a whole.

It can keep a well-insulated house warm with its heat, in almost any weather. The same can be done by an exhaust air heat pump as well. Some systems use a lot of energy to heat homes, but when they work well, they can cut energy use by 50%, compared to traditional heating systems.

Running costs are low with an underfloor heating system, and the exhaust air heat pump does not need much attention.

Natural Replenishment Of Exhaust Air

For those inside the building, exhaust fans constantly blow out fresh air. There is a big difference in pressure between the environment inside and outside. In this way, when there is a significant pressure difference, air moves.

Air is less likely to travel from one location to another with a lot of force. In other words, if there are any holes in the building envelope where the air is being mechanically pushed out, then some of the outside air that is not pushed out by the air conditioner will come in.

It can be very effective and efficient to ventilate certain places when the air outside is good, as long as the exhaust air is not controlled. As a result, if the outside air is very wet and either hot or cold, it may not be able to come into the building naturally. This is because there are too many pollutants (for example, dust or pollution).

Components And System

The essential parts in an exhaust air heat pump are:

• a water heater
• an extractor fan
• a heat pump 

When there is a lot of moisture in a room, such as a bathroom, utility room, or kitchen, the system extracts air through a series of ventilation ducts. A heat exchanger takes the energy that is in the air and moves it to a refrigerant, which then cools down. 

The refrigerant boils and then evaporates before being squeezed into a tighter form as a gas. The compression causes heat to be released, which goes to the supply of hot water, the hot water heating system, or the air that comes into the room that does not get wet.

There are ducts all over the building that must be built so that the exhaust air heat pump can get and send air to and from the building. This often occurs during the construction of a structure. It might not be possible to change some buildings that are old, or to make them more efficient. 

Benefits Of Exhaust Air Heat Pumps

There are several advantages to using exhaust air heat pumps, including:

• A reduction in money spent on gasoline expenses
• An attempt to reduce the environmental effect of buildings by reducing CO2 emissions
• Ensuring that the building rules are being obeyed
• An improvement in the quality of the air inside a building which is kept from becoming wet, by the ventilation of that building.

Conclusion

Exhaust air heat recovery is a critical way to save energy in buildings. It saves money because it does not have to heat or humidify the outside air that comes into the building. There will be a lot more dedicated outdoor air systems with exhaust air heat pumps (EAHP) in the future. These systems use vapour-compression refrigerant cycles to get energy from exhaust air.