A high-velocity (Unico) system delivers heating and cooling through small, flexible 2-inch tubing that fishes through existing walls, floors, and ceilings with minimal demolition — and discreet outlets that don't disrupt the room. That makes it ideal for older, historic, and architecturally sensitive Bay Area homes that can't take conventional ductwork. Paired with a heat pump, it provides efficient year-round comfort while preserving the home's character.
What exactly is a high-velocity system?
"Small-duct high-velocity" (Unico is the leading brand) uses a compact air handler and flexible 2-inch supply tubing instead of the large rigid ducts a conventional system needs. The tubing routes through chases, wall cavities, and ceilings that could never fit standard ductwork, and terminates in small round or slotted outlets that blend into the room. It's a fundamentally different delivery method designed for tight, finished spaces.
Why does it suit historic and luxury homes?
- Minimal demolition. No tearing up plaster, dropping ceilings, or boxing in soffits for ducts.
- Preserves character. Period details and clean modern lines stay intact; outlets are discreet.
- Fits where ducts can't. Solid masonry, lath-and-plaster, and architecturally unique layouts are no obstacle.
- Comfort bonus. The high-velocity airflow mixes room air thoroughly (aspiration), reducing hot and cold spots.
How does it compare to ductless?
Both add comfort without conventional ducts, but they look and feel different: high-velocity hides almost entirely with small outlets, while ductless mini-splits use visible wall or ceiling heads and offer per-room zoning. The right pick depends on aesthetics, zoning needs, and budget — see high-velocity vs. ductless. For mid-century homes specifically, see cooling an Eichler.
Design makes or breaks it. High-velocity rewards careful planning — outlet placement, tubing routing, and correct Manual J sizing. A specialist who knows these systems delivers invisible comfort; a generalist can leave you with noise or weak spots.
What does it cost?
High-velocity is a premium, design-intensive approach, so it typically sits at the higher end of the range — justified by the homes it serves. See how the number moves in the installation cost guide, and pair it with a heat pump to check rebate eligibility.
Why trust Air Synergy with high-velocity?
Air Synergy specializes in HVAC for distinctive Bay Area homes — historic, luxury, and architecturally unique properties. A family-owned team with decades of combined technician experience and a 4.9-star rating across 189 reviews, we design high-velocity systems that disappear into the home and perform. Explore specialty systems.
Your next step
Have a home that can't take conventional ducts? Book a free in-home consultation. We'll assess the structure and design a discreet high-velocity solution — in writing, no pressure.
System descriptions reflect standard small-duct high-velocity practice; design and sizing are done in person. Cost figures are ranges, not quotes; rebates are [GATHER]. Terms in the glossary. Company facts per Air Synergy.
Common questions
What is a high-velocity (Unico) HVAC system?
A high-velocity system delivers conditioned air through small, flexible 2-inch tubing instead of large rigid ducts. The tubing fishes through existing walls, floors, and ceilings with minimal demolition, and the small outlets are discreet — making it ideal for older, historic, and architecturally sensitive homes that can't accommodate conventional ductwork.
Why is high-velocity good for older and luxury homes?
Because it adds central heating and cooling without tearing up plaster walls, dropping ceilings, or running bulky ducts that would ruin period details or clean modern lines. The small tubing is routed discreetly and the outlets are unobtrusive, so you get modern comfort while preserving the home's character.
Does high-velocity cool as well as a regular system?
Yes — and it has a comfort advantage: the high-velocity airflow creates gentle 'aspiration' that mixes room air thoroughly, reducing hot and cold spots and even helping with humidity. Paired with a heat pump, it provides efficient year-round comfort. Proper design and sizing are essential to get it right.