One of our members recently asked me, “if you could create the ultimate HVAC system, what would it look like?” There’s really no one answer to this question, as the ultimate system is one that fits the building and your customer’s situation, lifestyle, and budget. But it got me thinking about where the industry might be in the future, so I set out to imagineer a system using existing technology to provide the best balance of comfort, health, safety, and efficiency.
There are essentially three home comfort deliverables: cooling, heating, and ventilation. Us airheads usually try to provide all three with a single system. While cost effective, this approach entails a number of compromises: Ducts are inherently leaky, poorly insulated, designed and installed. They have air distribution problems, zoning issues, noise, and health and safety issues (mold, particulates, etc.).
A “traditional” HVAC system must deliver a tall order. So at the risk of being called a blasphemer by my fellow airheads, I believe there are better ways to deliver comfort on the horizon.
By eliminating the ductwork, a cooling system could eliminate many air distribution-related sins. This could be accomplished using ductless multizone mini-split systems with a ductless fan coil in each room. These systems are becoming more cost effective for whole-house use every day.
The Pros: No ductwork, therefore less buildup of contaminants, better air filtration. Units are also becoming ultraquiet, reducing fan and air movement noise. Another major benefit is more precise cooling of a specific room or area.
The Cons: Potentially higher initial cost. More service and maintenance. In a home with eight fan coils you have eight sets of electronics and mechanical parts, eight filters, and eight fans that could break down. Because the fans are moving a small amount of air, they would likely last a long time. Another option might be a tightly sealed small duct high velocity system — but that’s another article.
In my book, the ultimate in comfort is radiant heating, especially radiant floor heating, which keeps your toes warm and overall feels great. The most efficient way to accomplish this in heating climates is with a boiler that provides space heating and indirect domestic water heating. In southern climates, electric radiant might make sense depending on heating degree days.
The Pros: Even comfort, a healthier environment, no contaminant buildup in ducts, ultraquiet, great zone control for more precise room load matching.
The Cons: It doesn’t work well on carpeted floors, requiring a major floor renovation in most existing homes. Of course, by eliminating carpeting, homeowners would enjoy the health-related benefits of better IAQ. Infloor radiant systems are harder to set back as the heat must overcome the thermal mass of the floor itself. It can also take objects longer to warm up, unless in line of sight of the radiant floor. Other options for those who want the benefits of radiant without floor installation include radiant wall or ceiling panels, or baseboard systems.
Homes and small commercial buildings don’t need thousands of CFM of ventilation. According to ASHRAE standards, we only need a fraction of the typical air moving through traditional duct systems (typically 60-150 CFM). Imagine a 2-in. piping network, similar to a central vac system, that brings in filtered air using a relatively small, efficient, and quiet fan. It could also exhaust stale air from the home using a sealed two-pipe system, perhaps made of PVC, with small variable speed fans that can dial in the exact amount of ventilation and exhaust air needed, slightly pressurizing the envelope for optimum safety and IAQ.
While fairly simple to install in new construction, this type of installation would be tougher in existing homes —but not impossible. Think about what is currently running throughout most existing homes: ductwork. What you have is a network of chases running throughout the home. What if we ran hydronic piping, control wiring, refrigerant lines, and even ventilation piping through these ducts?
Would there be challenges? Of course. But I think it wouldn’t take entrepreneurial inventors and manufacturers long to come up with ways to adapt existing duct systems to act as conduits for the new systems. In the future? Maybe. But if you think about it, everything mentioned here exists right now. It’s just a matter of figuring out how to put the pieces together to make it a reality.
Dominick Guarino is CEO of National Comfort Institute (NCI), (www.nationalcomfortinstitute. com), the nation’s premier Performance-Based training, certification, and membership organization, focused on helping contractors grow and become more profitable. His email is [email protected]. For more info on Performance-Based Contracting, go to WhyPBC.com or call NCI at 800/633-7058.