How Heat Pumps Keep Buildings Cool and Warm?

The traditional approach to managing temperature control in buildings often treats heating and cooling as distinct and isolated systems. Typically, heating is accomplished using primary fuels, furnaces, or electric resistance heaters, while cooling relies on air-conditioning units. 

Heat Pumps 
Image Credits: Elevate

Ensuring the harmonious integration of these systems within a living space has proven challenging, both in terms of environmental impact due to the significant carbon emissions generated by these units and the associated financial costs. However, this challenge has led to the emergence of a promising solution: the heat pump.

A heat pump is a technology with a two-in-one system used to heat and cool the building that is typically installed outside the building. 

In this article, we will explore the basic definition of heat pumps, their working, types, and features for your understanding.

What are Heat Pumps?

A heat pump is an equipment that transfers or pumps heat from one place to another so that the space is made cool or warm as per requirement. This two-in-one system is possible by using a reversing valve that allows one to choose to move heat from inside to outside (cooling mode) or to the reverse cycle (heating mode).

The air is drawn from a particular source and taken through several processes to finally provide the desired air temperature. 

Working and Components of a Heat Pump

The major components that take part in this process are the evaporator, compressor, condenser, and, reversible valve and distribution unit. 

Heat pumps switch between heating and cooling modes by reversing the flow of refrigerant in the system. This process is controlled by a component called a reversing valve, which is a key element in the heat pump's operation. Here's how it works:

Reversing Valve

The reversing valve is a four-way valve located within the heat pump system. It can change the direction in which the refrigerant flows through the system. When the heat pump is in heating mode, the reversing valve directs the flow of refrigerant to extract heat from the external heat source and release it inside. When the heat pump is in cooling mode, the reversing valve reverses the flow, extracting heat from the inside and releasing it outside.

Note

The evaporator evaporates the refrigerant in a liquid state into a gaseous state using heat. The condenser condenses the refrigerant from the gaseous state to a liquid state.

Heat Pumps in Cold Season ( Heating Mode)

When you set your heat pump to heating mode, the reversing valve directs the flow of refrigerant through the evaporator coil outside to absorb heat from the external source (air, ground, or water). The refrigerant then carries this heat to the condenser coil inside, where it is released to warm the indoor air. 

• Evaporator / Outdoor Coil: Cold air from outside is drawn into the heat pump unit, passing over an evaporator coil containing a refrigerant fluid. The refrigerant is at a very low temperature, and it absorbs heat from the outdoor air. This converts the refrigerant into a gaseous state.
• Compressor: The refrigerant, now in a gaseous state, is compressed by the compressor unit. This process raises its pressure and hence the temperature significantly.
• Condenser Coil: The hot, pressurized refrigerant is then circulated through a condenser coil located inside your home. Here, it releases the absorbed heat, warming the indoor air.
• Distribution: The warm air is distributed throughout your home via a forced air system (ducts and vents) or a ductless mini-split system. It heats your living spaces efficiently.

During the heating season, heat pumps are highly efficient because they move existing heat rather than generating it from scratch, making them more energy-efficient compared to traditional heating systems like furnaces.

Fig.2. Heat Pump Reversible System
Image Credits: Idronics

2. Heat Pumps in Hot Season ( Cooling Season)

Conversely, when you set your heat pump to cooling mode, the reversing valve switches the flow of refrigerant. It directs the refrigerant to absorb heat from inside your home's air and release it outside to cool the indoor air.

During the cooling mode, a heat pump operates similarly to an air conditioner, removing heat from inside your home and releasing it outside. Here's how it works:

• Evaporator Coil: Warm indoor air is drawn into the heat pump, passing over an evaporator coil. The refrigerant inside the coil absorbs heat from the indoor air, causing it to evaporate into a low-pressure gas.
• Compressor: The refrigerant in its gaseous state is then compressed by the compressor, which raises its temperature significantly.
• Condenser Coil: The hot, pressurized refrigerant is pumped outside to a condenser coil. Here, it releases the absorbed heat into the outdoor air.
• Distribution: The cooled air is circulated back into your home, lowering the indoor temperature and providing a comfortable cooling effect.

In this mode, heat pumps effectively act as air conditioners, transferring heat from the indoor environment to the outdoors, resulting in a cooler indoor space.

The ability to switch between these modes, along with their energy-efficient operation, makes heat pumps a versatile and cost-effective choice for year-round climate control.

Read More:  Basics of Home HVAC Systems and How to Maintain Them?