One year inspections are fun because I ask if there are any things in particular the client wants me to look at.
Often I get a response like this: "Until recently there was a puddle on the floor of the furnace room. It leaked all summer. Now it has stopped."
When I hear that I am pretty sure the leaking has to do with AC condensation, for some reason. And now that the AC isn't operating the mysterious leaking has stopped.
But I go look anyway!
When I entered the furnace room and saw this I was not surprised.
Overhead is the main HVAC supply duct for the main level.
Off of this runs each of the individual, smaller duct tubes that service the various rooms of the main and basement levels.
The unit is to the left.
It is the horizontal duct in the center of the photo that interested me.
That is the main exhaust leaving the furnace, for heat and AC.
Notice the angle!
When things are running well the AC air coming out of the unit is around 45 - 50F. That's pretty cold air!
It is so cold as compared to the air in the room that condensation will surely result.
Ideally the condensation is contained inside the unit, or directed there for discharge elsewhere.
In this case the angle of the duct is directing some of that condensation away from the unit, and toward that curved section of the duct.
It would sit there, except for one thing.
See the teensy hole?
That's in that "painted" joint! It's also a low point!
That joint is painted with a latex duct product intended to seal small gaps in the metal duct work.
It"s pretty good stuff! But not when there's a hole, or when a hole opens up!
Surely, all summer, that hole leaked, dripping water onto the floor of the room.
A lot of water? Probably not. But a puddle resulted every time the system ran for a while.
That they never noticed the dripping surprised me! I asked, and they had not!
My recommendation: when your unit is doing something odd during a particular season, there is probably a reason related to that season! Maintenance requires a couple of things. First, listen to your unit. If it starts sounding differently call a professional. Second, watch your unit operate. If it does different things (like in this case water dripping from a hole that opened up) call a professional. BUT IF YOU WANT A PROBLEM INVESTIGATED BY AN OBJECTIVE PROFESSIONAL - CALL A HOME INSPECTOR! He might just be able to diagnose the problem!
Jay Markanich Real Estate Inspections, LLC 
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560
