If you have an older home — built before the 1970s — with plaster walls, no attic, or a historic designation that prevents you from cutting through structural elements, you might assume ductless or ducted heat pumps aren’t an option. That’s where high-velocity HVAC systems come in.

What Is a High-Velocity HVAC System?

High-velocity systems (most commonly SpacePak or Unico) use a small air handler connected to a network of 2-inch flexible mini-ducts that snake through walls, floors, and ceilings with minimal demolition. Instead of large rectangular ducts, the system uses flexible 2-inch tubing that can fit through wall cavities, under floors, and through finished spaces.

At each room, a small round “aspiration outlet” (about the size of a coffee mug) delivers conditioned air at high velocity. The high-velocity airflow creates “aspiration” — drawing room air into the supply air stream and creating efficient mixing without drafts.

SpacePak vs. Standard Mini-Split vs. Bosch Ducted

When High-Velocity Makes Sense in Denver

Denver’s historic neighborhoods — Capitol Hill, Highland, Cherry Creek, Congress Park, and Washington Park — are full of Victorian and Craftsman homes with plaster walls, finished basements, and no room for standard ductwork. High-velocity systems are a popular choice for homeowners who:

• Want invisible HVAC with small 2″ outlets that barely show
• Have historic landmark designations limiting exterior modifications
• Have plaster walls and finished ceilings with no easy access
• Want to preserve the architectural character of their home

Is High-Velocity Right for Your Home?

High-velocity systems are a specialized solution that works extremely well in the right context. They’re not for every home — but for historic Denver properties that can’t accommodate standard ductwork or mini-split wall penetrations, they can be the ideal answer. Call us for a free consultation to evaluate all options for your specific home.