I finished watching TOH’s 2000 Milton, MA project on a 250-year old colonial home. While it wasn’t explicitly stated (that I caught) they used what appears to be high-velocity conduit, and each of the floor/ceiling receptacle were only 1.5-2″ in diameter. I remember these receptacles from the 2004 (Manchester?) mansion project, and Richard states it was a high-velocity system there, because of limitations in in cavities for running conduit.
I am now wondering, though, when a high-velocity system should never be used, and how returns for volumes fed with HV systems are employed. I guess traditional returns, if applicable, could still be used provided the CFM (cubic-feet/minute) is sufficient, but I really am not an HVAC person. Also, I was surprised that in the 2000 Milton project that what I though HV applications were appropriate for were being used in otherwise small, low-ceiling applications.
Just curious. Any enlightenment would be appreciated.
Replies
When to use high-velocity HVAC?
Works best if you have at least some hearing impariment.
Well, I don't normally place my ears/head at the receptacle so I'd imagined they'd design the opening to not being a problem. I doubt it sounds like a train horn.
Not if it's speced and installed right.We used high-velocity in new construction for two reasons: easier to route the small ducts with our configuration (still need a normal-sized trunk line), and better circulation in an open space with large volumes.
There are no applications, residentially speaking, in which should not install an HV system over a standard system. There are plenty of examples where the only system that you can install is an HV type, because of access.
The high velocity systems are more expensive than a "standard" system, and adding heat to them can be difficult. The returns are typically one-per-unit and sized as the manufacturer recommends. They can be properly utilized in most spaces, and, if sized and installed by competent folk, practically unnoticeable. Also, typical applications for HV systems are in retrofit where heating is covered by a hydronic or steam system, else in new construction with RFH installed for heat.
The air handler/forced-air furnace market has many more varieties of manufactures, quality and features whereas the HV market is covered by a much smaller contingent, two or three major players in the US.