It was spring of 2008 and I had lived in my 1929 home in York, PA for a little under half a year. This home had not been remodeled since 1952, so it was in dire need of a little updating. Since a lot of the work was wall repair and refinishing, I figured this would be as good a time as any to rough in supply air vents for a new A/C system. But, like most projects I have undertaken, I let the whole thing expand, unchecked, in true “Tim the Toolman” fashion….
First it was roughing in the vents, which led to “well, if I am going to put the vents in, I might as well install the connecting ducts.” When that was complete, naturally my next thought was “I might as well run the main supply trunk, while I’m at it,” followed by “I better get the power wiring run up from the basement.” You can see where this is all going: by the time June rolled around, the system was fully installed.
Okay – I’m not your AVERAGE homeowner. I actually have several years of experience as an HVAC contractor; otherwise I would not have undertaken such a project. Still, I learned an important lesson that I might not have as a contractor. When it comes to an AC system, bigger is definitely not better.
The 2-Ton Bargain I Couldn’t Pass Up…
Prior to ordering the cooling equipment, I decided it would be wise to run a computerized load calculation (often called a Manual J) on the house, which is what I would have done for any of my clients. Even with some wall and attic insulation factored in, my estimate came in a little over 32,000 BTU.
I planned to install a three-ton (36,000 BTU) system, but when I was presented with a sweetheart of a deal from my boss on a “scratch-and-dent” (slightly damaged) two-ton unit, I took it, not wanting to hold up my progress.
Now, some contractors would say I was nuts for putting in a system “too small” for the home but my wallet was talking louder than my professional inclinations at that point. Besides, it was my own home, so if it didn’t cool that well when it got very hot, it wouldn’t matter all that much. Plus, I had designed the duct system for maximum performance and even distribution, which would help offset some of my capacity issues.
“I can’t believe it’s 78 degrees in here…!”
I’m happy to report that in this case, haste did not make waste – in fact, quite the opposite. Turns out I shouldn’t have worried about the smaller sized system at all.
Since the system, by virtue of its smaller capacity, had to run longer to reach the thermostat setting, humidity removal was dramatically increased, thus making the air feel cooler than the temperature would indicate. So when it was 94ºF outside, a setting of 78ºF inside actually felt cold because the air was so dry. The true test was the fact that I never had any problems with mold or mildew anywhere in the home, even in the bathroom, which had no vent at all in it, due to its physical location. Microorganisms won’t form when they don’t have moisture for growth.
Longer run cycles also yield a gradual cooling process, which helps maintain a more uniform comfort level, with less temperature variance room-to-room.
There are a couple of other advantages to this: (1) machinery lasts longer when it isn’t turning off and on a lot. (2) an air conditioning unit consumes less electricity in normal operating mode than it does at start-up, so systems that run longer and cycle on and off at fewer intervals are actually more efficient.
So let’s add them up: more reliability, more comfort, a mold-free, healthier home, lower operational cost…pretty solid reasoning, if you ask me.
I’ve never forgotten the practical experience that this project taught me. There are many contractors who would rather upsize a cooling or heat pump system to cover for lack of real-world experience, or just to satiate the customer’s request–or their own desire–to install a system of greater capacity than is required. I now fall on the side of humidity control every time, even when my motive is questioned. The key ingredient with comfort cooling is humidity removal; sensible cooling (that temperature that registers on thermostat) is a secondary benefit.
Brad began his career with Boyce Heating & Air Conditioning, York, PA, in 1985. Boyce did residential and light commercial systems, with a special interest in places of worship and civil organizations. Boyce also worked with Habitat for Humanity, in urban redevelopment projects in York. Brad served as general manager of Going Aire in Key Largo, FL, from 2010 to 2011; he is currently helping Habitat For Humanity with a “green technology” home project in Plantation Key, FL, and with other worthwhile endeavors.