Not sure if you’ve noticed, but it is HOT out there in Central Kentucky! Your A/C system is probably struggling to keep up, and there are many possible reasons for that (GET UP AND CHANGE YOUR FURNACE FILTER RIGHT NOW!), but one possibility may be what I saw in a crawlspace I was inspecting this week.
The HVAC system was producing cool air from the supply ducts, but the system was still struggling to keep up with the thermostat demand (keep in mind, it was 90°F outside so we can’t be too hard on the poor thing!). The house was decently insulated where I could see the value in the attic, and it was a fairly typical single-story home with a crawlspace below and the air handler and ductwork located beneath the floor.
Upon entering the crawlspace, what I found was a condition I’ve witnessed many times before in my 12 years as a Professional Home Inspector in Central Kentucky – cold air hit me in the face when I opened the access hatch (hurray for me, I was dying wearing my coveralls and other PPE!) and I saw significant amounts of water dripping off of the bottom of the metal air supply ducts.
Wait, did I just say water was dripping throughout the crawlspace and that this is a common occurrence in other houses as well?! Yup, that’s correct! So what was going on??
Here’s the scoop. The ductwork was uninsulated, poorly sealed, single walled metal. Hot, humid air enters the crawlspace through the foundation vents, and this occurs at the same time you’re running your A/C system on full blast to try and stay sane in the house above. The hot air meets the cold metal ducts and condenses on the cold duct surface (it’s just basic physics, people…I guess…I don’t know, ask my 16-year-old niece who is WAY better at understanding science than me!!), causing moisture in the air to condense into liquid water on the cold duct surface.
Over time, that excess moisture can contribute to mold growth, wood decay, elevated humidity, and even shorten the life of the duct system.
The warm, humid crawlspace air transfers heat into the cold metal ductwork, warming the conditioned air inside the ducts before it reaches the living space – and this makes your system have to work harder, longer, and less successfully.
Another issue was that the duct joints and seams weren’t properly sealed, allowing conditioned air to leak into the crawlspace instead of reaching the rooms above. That’s a big reason why it felt so cool to me when I went to crawl below the house – good for the inspector, bad for the homeowner.
In this situation, the solution to your energy loss and moisture issues? Have your ducts professionally sealed and insulated, and voila! Your thermostat now has a much better chance of keeping up in this oppressive heat!
Something else to consider though is that anytime the outdoor humidity is consistently over about 60%, the air being pulled into your crawlspace through the foundation vents has enough moisture in it to facilitate mold growth on the wood structure and attract wood destroying insects, like termites.
In many Central Kentucky homes, a properly designed crawlspace encapsulation system can be an excellent long-term solution to high moisture/ventilation issues. This is a process that involves installing a completely sealed vapor barrier over the ground and up onto center columns and perimeter foundation walls, sealing off foundation vents, and installing a crawlspace grade dehumidifier.
Every detail of that type of setup matters, so if you’re considering exploring that type of setup, I’d recommend having a professional install it, but definitely something to think about for maintaining a healthy crawlspace in a hot, sticky climate like Kentucky’s.
If your home has a vented crawlspace and your air conditioner seems to run constantly every summer, it may be worth having the crawlspace and ductwork evaluated. Sometimes the problem isn’t the HVAC equipment at all—it’s a litany of things happening under the house.
But seriously, GO CHANGE YOUR FURNACE FILTER!!
Kari Cheek has been a licensed Home Inspector in the great state of Kentucky since 2014.
Need Inspection Services in Central Kentucky? Schedule your appointment today!
Kari Cheek (KY HI #103786)
Rosie Home Inspections
(859) 227-1780