Invisible HVAC for an old house?

By: Shannon Lee , Contributing Writer
In: Old Houses, Old House Construction, Home Improvement Tips, Technology

One of the biggest problems I ran into with old houses was the difficulty in cooling them. From the windows that were sealed shut with decades of paint to the small spaces that were simply impossible to fit ductwork through, the options for making the home more comfortable were few and far between.

My usual method of cooling — when I could get the windows open — was simple window air conditioners, supplemented by oscillating fans. But even with the largest units, it was sometimes impossible to get cool air to areas of the house that really needed it. A good HVAC system would have been welcome, but the configuration of lovely old Victorians often made discreet installation impossible. Did I want to be comfortable or maintain historical integrity? It was a terrible decision to make.

If I had known about mini-duct systems, I could have had the best of both worlds.

How mini-duct systems revolutionize old house comfort

A mini-duct system is just what it sounds like. The ducts are small, about three inches in diameter, and flexible enough to be snaked through walls without disturbing them. Rather than terminate in large grilles or registers, these ducts end with an opening that is smaller than that of an audio CD. Air is forced through the ducts at higher speeds than your typical HVAC unit, mixing the air around and resulting in even more cooling than what you might get from a large, traditional air conditioning system.

A mini-duct system operating on dehumidifying mode can remove up to 30 percent more humidity than a traditional system. That saves money and keeps you feeling cooler by removing the “mugginess” from the air. As anyone who has lived in an old house knows, that muggy feeling is what makes the hottest days truly unbearable.

Installation of a mini-duct system is fast and easy, taking only a few days. The grilles are unobtrusive and can be cut anywhere you like, thus allowing you to choose clever hiding places. The air flow is almost silent, comparable to other HVAC systems. The ductwork is flexible and sturdy, with only an average of 5 percent leakage, as compared to the 25 percent leakage you might see in traditional models.

The downside? The cost. Prices for the system and installation are typically 25 to 40 percent higher than that of a traditional system. However, preserving the integrity of a historic home while still keeping your cool can mean the bottom line is worth the price.

A modern unit hidden away in restoration

For those who are painstakingly restoring a home, even the parts that must be completely redone, such as replacement windows, are styled to look as much like the original as possible. Since such a luxury is impossible with a modern HVAC system, hiding mini-ducts throughout the home is the next best thing. If you get creative about hiding the registers and thermostat, it is entirely possible that guests won’t notice the system at all until they ask why the house seems so cool in the middle of a sweltering summer.