by Gerry Wagner
Duct-Free vs. Ducted: I have always made it clear in my GREE mini split training events that I’m not here to disparage unitary (ducted) systems … they aren’t going anywhere nor should they. Mini splits are simply an alternative to ducted systems and not always the better choice.
OK … with that established, let’s talk ducted.
My home in Pennsylvania is a perfect example of where mini splits would not be the best option … let me explain.
The home was built in 1980 and it is very rustic in design … VERY rustic! The interior is a combination of exposed brick and repurposed barn wood … the entire house, every room. The house had no HVAC until 1996 … well, it had H (electric baseboard heat). In 1996, a previous owner had a Carrier R22 heat pump installed with both overhead (attic) and floor level (basement) ductwork.
Mini split evaporators on brick walls didn’t appeal to me (drilling through brick was even less appealing). Ceiling cassettes were equally problematic because of multiple barn beams, exposed, running within each room’s ceiling and a very low attic above with no floor.
The system had to be changed as it was 25 years old, R22 and killing me each month when the utility bill came due … especially in the winter.
I contacted my local Carrier dealer, the same people who have been servicing the existing Carrier system in the house since its installation. They gave me three options … a good, better and best selection.
In a stroke of dumb-luck, GREE was introducing an inverter-based, 20 SEER complete unitary system called the FLEXX here in the United States. Perfect timing!
The GREE FLEXX outdoor unit looks very much like a mini split outdoor unit … horizontal discharge, tall and thin. The fan coil is nothing particularly exciting … A-coil, TXV, vertical or horizontal adaptability and available in four capacities (24, 36, 48 & 60K).
The outdoor unit is where the magic takes place!
Two units available in four capacities … one unit can be set to either 24 or 36K and the second unit can be set to either 48 or 60K. The magic centers around the two-stage enhanced vapor injection compressor, a unique GREE design that allows for a cooling range of 5°F – 129°F (100% cooling capacity up to 115°F and 78% up to 129°F) and a heating range of -22°F – 75°F (100% heating capacity down to -5°F and 78% down to -22°F).
I chose to install a 10KW electric emergency back-up heat strip (a GREE provided option) even though anything below -22°F here in central Pennsylvania would probably indicate the apocalypse and I would probably have bigger problems than my heat pump not keeping up.
The entire installation was documented and updates posted on my LinkedIn profile (just search for Gerry Wagner on LinkedIn and scroll through my past posts) … follow or connect with me while you are there. I will be conducting GREE FLEXX training events this fall with a comprehensive curriculum dedicated to this unique product.
The GREE FLEXX outdoor unit can be matched with any existing 14 SEER or higher heat pump air handler that utilizes R410A refrigerant (currently only AHRI recognized match is with the GREE FLEXX indoor unit … other AHRI matches to come). The system can be controlled by any 24V heat pump thermostat.
My original plan was to locate the GREE FLEXX outdoor unit at the same location as the existing Carrier heat pump however, because I needed to change the lineset which runs the entire length of the home in a very low attic space with no floor, I decided to take the easier route and place the GREE FLEXX outdoor unit just above where the indoor unit is located in the basement. I did have some concern about operating noise as this would mean the GREE FLEXX outdoor unit would now be located right outside the guest bedroom. I can testify that with an operating level of 55 dB, the GREE FLEXX outdoor unit is whisper quiet, which for me unfortunately means guests might stay longer.
The GREE FLEXX indoor unit has its own set of valves which allows for evacuation and charging at the indoor unit … think about that on a cold, winter day or a hot, raining summer day! The A-coil comes factory charged with .55 lbs. of R410A, not nitrogen … because of this; all you are evacuating is the lineset. There is no need to add additional refrigerant for a lineset 31’ or less (not to be less than the minimum 15’). The maximum lineset length is 98’. There is no need to insulate the liquid line as, unlike the inverter mini split, a TXV is in the GREE FLEXX indoor unit.
Look, I know I risk coming off like a hypocrite … me, the mini split, DUCT-FREE guy now talking ducted but, come on … this is different … this ain’t your typical unitary system. This is the GREE FLEXX … this is GREE jumping into the deep end with a versatile, unique, efficient and complete system that in my opinion is a game changer.
ABOUT THE AUTHOR: Gerry Wagner is the Vice President of HVAC Technical Training for Tradewinds Climate Systems. He has 41 years in the HVACR industry working in manufacturing, contracting and now training. You can contact Gerry by email: and also please visit our website: