Is HVAC Just Equipment and a Price?

25 years ago the HVAC industry was basically just installing heating/cooling equipment and typically some exhaust such as bath fans and likewise, the building industry was basically to design a house that wouldn't fall over. These two industries have taken a 180 since. We are building tighter homes than ever before with more stringent codes and standards. Could these new codes and standards be hurting your home and your health?

By early 2016 I was really good at repairing HVAC systems, I could typically diagnose a failure within 20 minutes of arriving to a call and diagnose it with a 98% accuracy. But something else was happening to me where I had a near 0% accuracy of diagnosing the issue and that was complaints of the home being uncomfortable even though the HVAC was working properly. Consumers where increasingly calling about high moisture in the home as well as extremely dusty homes and I couldn't figure out what to do. The simple answer seemed to be installing dehumidifiers and fancy UV products. I mean, I live on the coast in the south so that makes sense right? Also, it seemed fair to say "well maybe you just need a bigger HVAC unit"! The worst part is, all the forementioned solutions made the issues worse than before or had no effect; but they cost a lot of money so contractors love them. So what was I to do?

I was lost and grasping at straws until I found a community of great mentors, most notably Sam Myers of RETROTEC. Sam has a vast knowledge of home performance testing and not just for the purposes of efficiency, but most notably for making a home safe and clean. RETROTEC is a company that produces equipment that test duct systems, home tightness, air leaks, drafts, and so much more. Sam showed me how to use these tools to diagnose the issues that clients were dealing with.

The tighter the construction is (like our newer homes built in the last 20 years), the more important it is to accurately size equipment. Think about this, the only time your HVAC system can remove moisture from the home is when it's running. So it's fair to say that the longer a system runs, the more moisture it can remove right? Hold up, if the system is running my electric bill is going up right? The answer is both yes and no. If your ac unit is oversized it's going to run less per cycle, but at the same time it's going to cycle off and on more frequently because it's going to satisfy the thermostat quickly. Now we deal with a system that lacks the ability to properly remove moisture as well a system that is starting and stopping more frequently. Why is a car with highway miles worth more than a city driven car? Let that sink in cause HVAC is no different. It's harder on the equipment. So the oversized unit is driven in the city and it wont last as long plus it's not removing the moisture... Sounds like a raw deal.

To properly size an ac unit we need to utilize an ACCA approved heat loss/heat gain (load calculation) software to now the cooling load of a structure. The factors that determine the HVAC size are things like exterior walls/floors, attic construction, roofing materials, windows/coverings, exterior doors, exhaust, appliances, occupants/habits, and infiltration. Wait, what in infiltration? Infiltration is basically a fancy way to say that nature is always going to try and equalize and we build homes in nature so when we cool and dry out the inside of the home, the energy of the hot and humid air outside wants to come in and ruin your day. The atmospheric pressure on the surface of the earth at sea level is roughly 14.7 pounds per square inch absolute and when we turn on an exhaust fan, dryer, kitchen exhaust hood, and sometimes our hvac systems, we pull the home below atmospheric pressure. When the home is below atmospheric pressure, nature has to equalize and it will do this via air leaks from the attic, crawl space, around windows, walls, and anywhere it can. This unfiltered, untreated, high energy air causes our homes to be inundated with moisture and harmful particulate matter. The way we measure this problem is with a blower door.

The blower door is a system of tools used to measure the infiltration of a structure, thus allowing us to truly size hvac equipment properly and giving the information needed to combat the below atmospheric pressure issue. A properly sized hvac unit will remove moisture on an engineered level of accuracy ensuring that we are maintaining a healthy environment that won't propagate the formations of bacteria. The last part of that equation is if I know that a home goes 200 cfm below atmospheric pressure with all the exhaust equipment running, I can design a system that filters and treats enough make up air that the home always stays positive, stopping the outside air from being pulled into the home uncontrolled.

Proper filtration is another key to this and is equally misunderstood and overlooked in my industry. As a younger service tech, I was always told by the older techs that the cheapest filter out there is the best for hvac equipment because it allowed for the best airflow. Sounded reasonable to me. Unfortunately that couldn't be further from the truth and that advice can cause more indoor air quality issues than you can imagine. I did a video recently on my Youtube channel showing the performance of a 2 inch filter compared to a 1 inch filter which clearly shows based on engineering data that the 2 inch filter supported better air flow than the 1 inch. The larger the filter, the wider the available surface area is for air to travel through the filter. When we give the air more room to spread out, the air moves slower. Slower is better for 2 main reasons. The first reason is that the slower the air moves over the filter, the better performance you will get and capture smaller particulates making the air in your home cleaner. Also, the slower the air is moving over the filter, the more efficient your hvac will be as it won't be working as hard to do the same job. Slower air does not mean less air, it's actually the opposite as it will reduce the pressure in the duct system, allowing more air to flow smoother throughout the home.

This blog could go on for days as I have barely scratched the surface of the issues in a home and the appropriate solutions, but at this point I may be losing your interest. I will finish with saying that the days of hvac repairs just being the equipment and ductwork are gone and a great technician is one that understands "your entire home is system that we need to diagnose". Thank you for reading.