How the Heat Pump Works

ALTAL heat pumps with DC inverter and EVI technology

What is a Heat Pump and How Does it Work?

Note on managing household energy consumption

Heat pumps are highly efficient heating and cooling systems that can significantly reduce electricity costs. When considering your home as a system, it is advisable to minimize heat loss in areas such as air leaks (through cracks and holes), walls, ceilings, and poorly insulated fixtures.
Addressing these issues can allow for the use of a smaller heat pump, reducing equipment costs and improving system efficiency.
A number of publications explaining how to achieve this are available on the ALTAL website or online.

Basic Concepts

Heat pumps are a proven technology, used for decades worldwide for heating, cooling, and, in some cases, for hot water. In fact, the principles of heat pump technology can be observed in everyday life: refrigerators and air conditioning units operate on the same principles and technologies. This section presents the basic principles of how a heat pump works and the different types of systems.

Why Choose a Heat Pump?

Heat Pump as a Modern System

If you're analyzing heating and cooling options for your home or looking to reduce electricity bills, consider using a heat pump. Heat pumps represent a proven and reliable technology capable of providing year-round comfort control, offering warmth in winter, cooling in summer, and, in some cases, hot water for your residence.

Heat pumps can be an excellent choice for various applications, both for new homes and for upgrading existing heating and cooling systems. They can also replace existing air conditioning systems, as the additional costs for transitioning from a system that only cools to a heat pump are often quite low. Given the numerous types and options available, it can be challenging to determine whether a heat pump is the right choice for your home.

Advantages of Heat Pumps

Efficiency

Compared to other heating and cooling systems, heat pumps are more efficient. They consume less energy and fuel to heat or cool your home, with some water pumps achieving an efficiency coefficient of up to 600%. They also have a lifespan of up to 50 years.

Three Functions

Investing in a heat pump offers the advantage of providing heating, cooling, and hot water in one system. This can save you money by reducing costs associated with installing two separate systems. Additionally, it takes up less space as it is a single system with three functions.

Emission Reduction

One of the primary advantages of heat pumps is their eco-friendliness. Since they do not rely on fossil fuels, they do not emit harmful vapors into the air. Reducing carbon emissions helps the environment and also saves homeowners money annually.

Minimal Maintenance

Heat pumps require no special maintenance. Their low operating costs are a significant advantage for homeowners looking to save money on costly home renovation projects, contributing to long-term savings.

ALTAL Air-to-Water Heat Pumps

Air Source Heat Pumps

Air-to-water heat pumps use outside air as a heat source for heating and as a heat sink for cooling. These systems can be divided into two categories:
Mini-Split: An indoor unit is placed inside the house, served by a single outdoor unit, which contains the compressor, air heat exchanger, and other components. The indoor unit has only the water heat exchanger and circulation pump. This type of heating can operate down to ambient temperatures of -15°...-20° C when using DC Inverter and EVI (vapor injection) technology.

Mini-Split: This type of pump uses water as a heat transfer medium for heating, cooling, and hot water production for household use.
Full-Split: In this system, only the heat exchanger and fan are located in the outdoor unit, while the compressor and other components are in the indoor unit. It can operate down to -25°C, using the same technology.
Multi-Split: These systems have multiple indoor units in the house, all served by a single outdoor unit, with slightly lower energy efficiency.

Variable Speed Heat Pumps
It is essential to consider the efficiency of new compressor models that enhance seasonal performance.

Units that meet a minimum SEER and HSPF requirement typically feature fixed-speed heat pumps. Now, variable-speed air heat pumps are available, designed to adjust the system's performance to better meet the heating and cooling needs of the house. They maintain maximum efficiency at all times, including in milder conditions when the system demand is lower.

Recently, air source heat pumps have been introduced that are better suited for operation in cold climates in Europe and the CIS due to EVI technology. These systems, often referred to as cold climate heat pumps, combine variable-speed compressor design with improved heat exchanger control systems, maximizing heat output at lower temperatures while maintaining efficiency in milder conditions. These types of systems often have higher SEER and HSPF ratings, with some reaching SEER 42 and HSPF close to 13.

Main Advantages of Air-to-Water Heat Pumps
Installing an air-to-water heat pump can provide a range of benefits. In this section, we will analyze how air-to-water heat pumps can help reduce your home's energy consumption.
• Efficiency
The primary advantage of using an air-to-water heat pump is the high efficiency it offers compared to typical systems like gas, wood, or electric boilers. At 7° C, the coefficient of performance (COP) for air-to-water heat pumps usually ranges between 2.0 and 5.4. This means that for units with a COP of 5, 5 kilowatt-hours (kWh) of heat are delivered for each kWh of electricity consumed. As the outside air temperature decreases, the COP decreases as the heat pump has to operate at a higher temperature differential. At -8° C, the COP can range between 1.1 and 3.7.
Market SEER values for units range from 7.1 to 13.2. Actual savings depend largely on where the heat pump is installed.
• Energy Savings
The higher efficiency of the heat pump can be explained by a significant reduction in energy consumption. Your actual savings will depend on various factors, including local climate, current system efficiency, the size and type of heat pump, and management strategy. Many online calculators are available to quickly assess how much energy you can save in your application.

ALTAL Ground-Water Heat Pumps

Geothermal Heat Pumps

Ground-water heat pumps utilize the soil or groundwater as a thermal energy source for heating and cooling. These systems are among the most efficient available and consist of two key components:

• Ground Heat Exchanger:

This component extracts thermal energy from the ground using geothermal probes or underground water. Various configurations are possible for the heat exchanger.

• Heat Pump:

Unlike air-water heat pumps, ground-water systems use a circulating fluid through the ground heat exchanger as a source (for heating) or as a discharge agent (for cooling). Both air and hydraulic systems (water-based) can be utilized in buildings. The working temperature is crucial for hydraulic systems, as heat pumps operate more efficiently at lower heating temperatures, between 35 and 50 °C, making them ideal for underfloor heating systems. Care must be taken when using them with high-temperature radiators, which require water temperatures above 60 °C, as these exceed the limits for most residential heat pumps.

Based on the interaction between the heat pump and the ground heat exchanger, there are two classifications of systems:

• Secondary Circuit:

A fluid (groundwater or antifreeze) is used in the ground heat exchanger, transferring heat from the ground to the pump through a heat exchanger.

• Direct Expansion (DX):

The refrigerant acts as the fluid in the ground heat exchanger, directly utilizing the heat extracted from the ground—no additional heat exchanger is required. In these systems, the ground heat exchanger is an integral part of the heat pump, functioning as an evaporator during heating and a condenser during cooling.

Ground-water heat pumps can meet a variety of comfort requirements in your home, including:

Exclusive Heating: The heat pump is used solely for heating, including space heating and hot water production.
Active Cooling Heating: The heat pump is utilized for both heating and cooling.
Passive Cooling Heating: The heat pump is used for heating and stops during the cooling cycle, directly cooling the fluid in the floor heat exchanger.

Main Advantages of Ground Heat Pump Systems

• Efficiency

In outdoor temperatures that can drop below -30 °C, ground systems can operate more efficiently, utilizing warmer and more stable soil temperatures (between +8 °C and +17 °C in our regions). The typical entering water temperature for the ground heat pump is generally above +5 °C, ensuring a COP of about 4 for most systems during cold winter months.

• Energy Savings

Ground systems significantly reduce heating and cooling costs, with energy savings for heating compared to electric, gas, or pellet stoves being approximately 65%. On average, a well-designed geothermal system saves about 20-30% more than the best-in-class air-source heat pumps, which cover the majority of the heating load of the building. This is due to the higher underground temperature compared to the air temperature during winter, allowing geothermal heat pumps to provide more heat in winter than air-source heat pumps.

Real energy savings will vary based on local climate, the efficiency of the existing heating system, fuel and electricity costs, the size of the installed heat pump, borefield configuration, seasonal energy balance, and the performance evaluation conditions of the heat pump.