Hybrid heating systems that include propane are one way for HVAC professionals to help meet this growing customer demand.

Hybrid heating systems offer HVAC professionals a laundry list of selling points. A savvy solution for both residential and commercial applications, they provide increased energy efficiency, optimal performance, cost savings, longer lifespans, and a smaller carbon footprint. There are also incentives and rebates available, benefiting both HVAC professionals’ customers and their business.

The basics of a hybrid heating system

A hybrid heating system, sometimes called a “dual-fuel” system, combines an air-source heat pump (ASHP) or ground-source heat pump (GSHP) with a high-efficiency natural gas or propane furnace.

The way it works is relatively simple: It calls for heating or cooling from the piece of equipment that will be most effective and comfortable, taking into account the outdoor temperature. The ASHP is called upon by the system’s controls to provide heat when outdoor temperatures are between 40°F or higher — a typical heat pump’s most efficient temperature range. When temperatures drop below 40°F and the heat pump becomes less efficient and has less heating capacity, the high-efficiency gas/propane furnace automatically cycles on to provide heat. The propane furnace typically delivers air at 115°F or higher, while the heat pump’s delivery air will be in the 90s or low 100s as outdoor temperatures drop. 

By capitalizing on the energy-saving strengths of both types of equipment, customers can experience year-round comfort and efficiency, not to mention more control over their utility bills.

An oversized cooling system oftentimes cools the air too quickly, lowering its temperature but not removing enough of the humidity. Because of this, indoor air is left cool but still humid, leading to discomfort, moisture, and potential mold problems. By combining a high-efficiency propane furnace with an ASHP or GSHP, though, HVAC professionals can improve cooling performance for their customers.

Additionally, hybrid heating systems provide a resilient heating system. If the ASHP compressor experiences a problem, the temperature of a home can still be maintained using the high-efficiency gas or propane furnace.

These synergistic systems can reduce carbon output

This component of any HVAC system has a growing importance in many areas of the country as construction professionals wrestle with how to reduce a building’s carbon footprint. Aside from renewable-based options, though, most heating systems will have carbon emissions linked to their operations.

In the case of ASHPs, many of these systems are powered by upstream, coal-fired power generation plants. In areas with significant coal-fired power generation, the inefficient electric resistance back-up heat in ASHPs creates much higher carbon emissions compared to ASHP-propane furnace hybrid systems, which avoid the electric resistance back-up.

Hybrid ASHP-propane furnace systems, however, avoid these emissions increases by relying on the furnace instead of electric resistance backup. As a result, hybrid systems in Midwestern locations can achieve a 38 percent reduction in carbon dioxide (CO2) emissions compared to an ASHP-only system, based on a recent study from PERC titled, “A Comparative Analysis of Residential Heating Systems.”

To put that into perspective, the difference each year in carbon emissions between an ASHP-only and an ASHP-propane furnace hybrid system is roughly equal to the greenhouse gas emissions of a passenger vehicle driven for six months. Over a system’s 15-year lifespan, the total difference in emissions would compare to the total emissions from a passenger car over roughly seven years.

Sharing these emissions figures with clientele can help HVAC professionals drive business for homeowners wanting a green solution in their home. In addition to a reduced carbon footprint, dual-fuel systems also offer customers lower energy costs, better performance, and longevity.

This story originally appeared in the August 2019 issue of SNIPS magazine.