A lot of the building industry and homeowners in the United States don’t want to see their HVAC systems exposed, even if it means high performance, healthy living environment, and total control. There is a magical way to have cake and eat it, too.
I design, specify and recommend mini-split heat pump systems because they are the quietest, most energy efficient, and most effective systems available for mechanically heating and cooling a home (or any building). Yes, they are even more efficient and effective than ground source heat pump systems (a.k.a. geothermal), and they cost less to install. I can prove it, but not now.
Most homeowners who say “no” to mini-splits are only familiar with the ductless fan coils (mini air handlers) that mount on the wall just above eye-level, in the ceiling above, or on the floor next to wall. They say, “Those things are too ugly, Chris!” By saying “no”, they give up the performance, low operation cost, location flexibility, indoor air quality, zoning capabilities, and controls of the mini-split technology. All of which are superior to conventional equipment.
Homeowner: “If you could make them disappear, Chris, than I would consider them.”
Hiding the wall-mounted units behind a dropped soffit or in a wall recess behind a decorative wood grille has been tried many times before, and it doesn’t work. They need to have the clearance all around them to be effective at circulating the air in the room they are in.
The magic is in the selection and design process. Instead of ductless, I specify the ducted fan coils that fit nicely in to a dropped ceiling cavity, crawlspace or attic (encapsulate these spaces, please), or just suspended from the ceiling in the mechanical room. They’re no more than 10″ tall, 48″ wide, and 32″ deep, depending on manufacturer. Conventional ductwork is used to deliver the air, and what the homeowner sees inside the home is no different than what they’re used to.
Some argue that the ductwork essentially wipes out the performance benefits of mini-split equipment, and I say, “Trust the duct design!” A properly designed and installed duct system will perform well if it follows industry standards and best practices. I use the a Manual D, a protocol from a ACCA, and design ductwork as long as 30′ that are tested after install and show that they meet the required air flow.
Every home we design, we integrate the HVAC design with the architecture, interior and structural designs early on to make sure the systems both physically fit and are sized appropriately to meet the heating and cooling demands. The Proud Green Home at a Serenbe is a perfect example; we decided on ducted mini-split heat pump system even before we started sketching the floor plan. On the main level, we designed dropped ceilings in closets, and we’ll run the ductwork through pre-engineered wood “I”-Joists above. For the second floor, we put the fan coil and ERV (Enthalpy/Energy Recovery Ventilator) in the encapsulated attic, which means all equipment and ductwork will be above the ceiling joists and below insulated roof rafters.
The system is made by LG‘s HVAC division. I chose their Multi-V line to get more flexibility (more available static pressure) with the duct design. Plus, we can specify equipment with enough heating capacity to avoid using expensive resistance back up heat. Here is the indoor fan coil (above – 10″h x 18″d x 35″w) and the outdoor unit (below – 54″h x 37″w x 13″d). Both are ridiculously quiet. The outdoor unit will never get louder than whispered conversation (35-45 db). The indoor units are even quieter (25-35 db).
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