June 9, 2025
If you’re interested in the most efficient HVAC solution available, new, cutting-edge hybrid VRF systems are an excellent option. However, there’s a good chance you’ve never heard of them since they’re a variation of a relatively new technology. Here’s everything you need to know about hybrid VRF systems and how they use refrigerant and water to deliver maximum efficiency.
What Is a VRF HVAC?
To understand hybrid VRF systems, you must first understand their predecessors. VRF stands for variable refrigerant flow. It refers to a specific type of ductless heat pump system. The name itself offers a decent clue as to how VRF systems work. It means that they include variable-speed inverter compressors. That allows a VRF system to increase and decrease its heating and cooling capacity as needed.
For example, if you only need heating or cooling in a single room, a VRF system’s compressor will run at low power. That reduces operating costs while still delivering the required refrigerant flow to the single operating air handler. Then, as demand increases, the compressor speeds up to accommodate it.
Many VRF systems have another high-efficiency trick. It involves using a third refrigerant line between each air handler and the system’s branch box. That extra line enables VRF systems to do something other mini-splits can’t: heat and cool simultaneously. The way it works is as ingenious as it is efficient. When one air handler operates in cooling mode, it would ordinarily send its collected heat to the outdoor unit for expulsion. When there’s another air handler in heating mode, the third refrigerant line instead carries that collected heat to the room that needs it.
That mode of operation is known as a heat recovery mode. On average, VRF systems that use heat recovery mode can reduce energy usage by up to 30%. It’s possible because collecting heat indoors is far more efficient than collecting it from outdoor air. Plus, repurposing already collected heat reduces the operating time of a VRF system’s compressor and outdoor unit.
So What’s a Hybrid VRF System?
A hybrid VRF system adds another step to the heat transfer process of a standard VRF system. Heat transfer between a hybrid system’s outdoor unit and branch box relies on a refrigerant. However, heat transfer between the branch box and the connected air handlers relies on water instead. The box contains a high-efficiency heat exchanger to move heat between the two loops.
The reason for the dual-fluid system is simple. It’s to enable simple compliance with ASHRAE 15 and 34 guidelines. ASHRAE, or the American Society of Heating, Refrigerating and Air-Conditioning Engineers, is the leading association of US HVAC professionals. They set safety and reliability standards that all reputable HVAC companies follow. ASHRAE 15 governs the volume of refrigerant considered safe inside a closed environment. ASHRAE 34, meanwhile, assigns safety classifications for HVAC refrigerants.
As you may know, earlier generations of refrigerants weren’t very environmentally friendly. The most popular among them was R-12, commonly known as Freon. It worked well as a refrigerant but destroyed the Earth’s ozone layer when released. It was also somewhat hazardous to breathe in high enough concentrations. Its successors solved the ozone problem, but they still aren’t safe for humans if released into enclosed spaces. As a result, VRF systems typically include sophisticated refrigerant leak detection technology. The idea is to alert you if a leak may pose a risk to anyone nearby. VRF systems also occasionally resort to extra ventilation methods to ensure safety.
By using water as a heat transfer medium indoors instead, hybrid VRF systems eliminate risk. That also eliminates the need for sophisticated leak detection technology, lowering system costs. Also, refrigerant leaks are one of the biggest threats to the longevity of HVAC systems. They can lead to compressor damage that forces expensive repairs and premature system replacements. By minimizing the total size of their refrigerant systems, hybrid VRF systems become less vulnerable to leaks.
It’s also worth pointing out that hybrid VRF systems offer simplified installation. Running the necessary water lines to support one is cheaper and easier than running the refrigerant lines that standard VRF systems need. Plus, water lines are far simpler to maintain and repair when necessary.
When Are Hybrid VRF Systems an Appropriate HVAC Solution?
Although installing a hybrid VRF HVAC system in a home is possible, it’s rarely an appropriate solution. Generally, they work best in large buildings, especially those with multiple small spaces needing HVAC coverage. The reason is that only small spaces create the possibility of violating the ASHRAE 15 and 34 guidelines. In larger spaces, there’s enough air volume to mitigate the risk of a refrigerant leak.
You’ll also find that the only hybrid VRF system currently available in the US is the Trane®/Mitsubishi Electric HVRF. That’s notable because it’s a commercial product aimed at facilities like office buildings, hospitals, and schools. While you could install the system in a large home, it would come at a significant cost premium relative to residential mini-splits.
Hybrid VRF systems would be overkill in smaller homes. Standard ductless mini-splits can support up to eight indoor air handlers and come in capacities of up to five tons. That’s large enough to cover up to 3,000 square feet. Also, you can install multiple mini-splits to cover larger spaces with excellent results.
You’d only consider a hybrid VRF HVAC system for your home to take advantage of simultaneous heating and cooling. If your home, like most, doesn’t feature small spaces needing dedicated air handlers, then a standard VRF system would suffice. Several standard VRF systems are available in the US and aimed at the residential market. Notable manufacturers of such systems include York, Carrier, and Hitachi.
There are also geothermal VRF systems that work exceptionally well in homes in St. Louis, MO. They provide all the benefits of air-source VRF systems with the added energy efficiency of a geothermal system. While somewhat costly upfront, they offer the ultimate in customizable, efficient comfort for your home.
Local Ultra-Efficient HVAC Experts
If you’re looking for an efficient HVAC solution for your St. Louis home or business, Scott-Lee Heating Company can help. We’ve served residents here since 1978, so we have ample experience meeting local comfort challenges. In that time, we’ve also become the leading local expert in efficient HVAC technology. That includes high-efficiency ACs, furnaces, heat pumps, and ductless mini-splits. We’re also one of the most experienced geothermal HVAC companies around.
Our HVAC technicians are NATE-certified, so they’re among the most skilled in the industry. Plus, we’re a Lennox Premier Dealer and a Mitsubishi Electric Diamond Contractor. That means we only sell and install the highest-quality HVAC systems available, including heat pumps. We also specialize in GeoComfort geothermal HVAC systems. Additionally, we’re members of the Air Conditioning Contractors of America and are Better Business Bureau accredited. If you want a new, efficient HVAC solution installed in St. Louis, call Scott-Lee Heating Company today!