How Does an Air Source Heat Pump Work with an Existing Furnace?

Integrating an air source heat pump (ASHP) with an existing furnace can create a highly efficient and flexible heating and cooling solution for your home. This article will provide a detailed overview of how these systems can work in tandem to optimize energy usage and enhance comfort.

System Overview

Our focus is on ASHPs which act as a primary heating and cooling source in conjunction with a traditional furnace. The ASHP can efficiently extract heat from the outside air, transferring it indoors during the heating season. In cooling mode, it reverses this process, moving heat from inside the home to the outside. The existing furnace serves as a backup when the outdoor temperature falls below the ASHP's optimal operating range.

Operation in Heating Mode

Heat Extraction: During the heating season, the ASHP operates by absorbing heat from the outside air, even in cold temperatures, using a refrigerant that circulates through the system. This refrigerant is a heat transfer medium designed to move heat from one area to another.

Heat Transfer: The refrigerant is then compressed, raising its temperature, and passed through an indoor coil where it releases heat into the home. This process continues even as outdoor temperatures drop, ensuring consistent indoor comfort.

Supplemental Heating: When outdoor temperatures become drastically colder than the ASHP's optimal operating range, the existing furnace can activate to provide additional heat. This ensures that the home remains warm without the need for constant ASHP use, which can be less efficient in extreme cold.

Operation in Cooling Mode

When cooling is needed, the heat pump reverses its cycle, absorbing heat from the indoors and releasing it outside. This effectively cools the home, creating a comfortable indoor environment during warmer weather.

System Control

Thermostat Integration: A smart thermostat can integrate and manage both the heat pump and the furnace. It can determine the most efficient mode of operation based on the current outdoor temperature and indoor comfort levels.

Dual-Fuel Systems: Some systems are designed as dual-fuel systems where the ASHP is the primary heating source, and the furnace is activated only during extremely cold weather. This setup maximizes the energy efficiency and cost savings of the ASHP.

Benefits

Energy Efficiency: ASHPs are generally more energy-efficient than traditional furnaces, especially in moderate climates. They can significantly reduce the energy required to heat your home, leading to lower utility bills.

Cost Savings: By using the ASHP as the primary heat source, homeowners can lower their energy bills, particularly during periods of lower electricity rates or when compared to the costs associated with fossil fuels.

Environmental Impact: Heat pumps reduce greenhouse gas emissions compared to fossil fuel heating systems, making them a more environmentally friendly choice for home heating and cooling.

Installation Considerations

Sizing: The heat pump must be properly sized for the home, taking into account the existing furnace's capacity. An appropriately sized ASHP ensures optimal performance and energy efficiency.

Ductwork: If the existing furnace uses ductwork, it may be possible to use the same system for the heat pump. However, modifications might be necessary to accommodate the ASHP's components and ensure proper airflow.

By integrating an ASHP with an existing furnace, homeowners can achieve a flexible and efficient heating and cooling solution that adapts to varying weather conditions, making the most of both technologies.