Home Heat/AC Vent leaking?

6/11/15 @ 10:47 AM
ORIGINAL POST
Cold Front
Cold Front
USER since 7/9/01
I was on the floor in my bedroom doing some stretching and I happened to glance up at the vents on the ceiling. There is about a 2 inch discolored area around all 3 of the vents on the ceiling. It doesn't look like a pattern from the air coming out because it is a uniform border around the vents. The first thought was that I had a leak. I took off the hardware and felt around the opening and the drywall was not wet and the insulation was also dry. I thought maybe I just didn't notice it before. I looked up in the attic through the cubby hole and there was no sign of any leaking.There was no obvious discoloration or dripline visible. Besides, the vents are at least 20 feet apart and not all are on the same rafter line. I also have lighting cans a few feet from the vents and there is no signs of problems with those. The air ducts look to be well insulated in a flexible silver tube. I had a new furnace and Ac put in a year ago. Any ideas? Mrt.
Post Your Comment
Displaying 1 to 10 of 11 Posts
6/12/15 @ 6:03 PM
Plmlk
Plmlk
MEMBER since 12/18/07
Also CF, he could have oversized your new AC.

When an AC is installed that is bigger than needed the discharge air drops considerably, and you may have a 25 degree temperature drop - and 20 degrees is typically considered the max.

The unit will typically short cycle as well. Sounds like something to look into given that you didn't have the issue with your old unit...

Post Your Comment
6/12/15 @ 9:06 AM
Cold Front
Cold Front
USER since 7/9/01
Thanks. I am now pretty sure that the moisture is not from a leak. I stuffed some tissues next to the vents and after this rain, it is still dry. I have a call in to my Furnace guy. I will ask about the blower setting. Thanks! Mrt.

Post Your Comment
6/11/15 @ 7:25 PM
Plmlk
Plmlk
MEMBER since 12/18/07
A couple of things...

A humidifier is typically energized by the control board, or by a current sensing relay that is attached to the low (heating) speed of the blower motor. If it was installed properly, the humidifier can only operate if the furnace is on.

Also, the colder the air is, the more likely moisture is to condense on the diffuser. No different than water droplets that form on a cold soda or beer can in the summer. To minimize this, ensure that insulation is present between the diffuser and the hot air from the attic. Ensure your filter is clean. If it is dirty your AC will move less air, and therefor the discharge air will be colder and more likely to cause condensation. Lastly, ensure the cooling speed on the blower motor is set for the highest speed. If it is set for med-high or low, you will not move as much air across your evaporator coil, and the discharge air will be colder, and more likely to be below the dew point, so moisture droplets will form.

Post Your Comment
6/11/15 @ 4:17 PM
Cold Front
Cold Front
USER since 7/9/01
I was wondering about that. There is no doubt that the new ac is tossing out some colder air. I can cool the house down much faster with the new unit. Maybe I will pull the metal grates off for a while and see if it goes away. I am not sure they even make them but would some other material resist getting as cold and causing this? Plastic perhaps? This would explain why it is happening on these ducts that are so far apart and not the lighting cans. Mrt I don't have the April Air activated. The only areas showing the stains are around the grates that the air comes out into the room.

Edited on 6/11/15 4:20 PM
Post Your Comment
6/11/15 @ 4:15 PM
Prop
Prop
USER since 4/9/03
If you have a whole house humidifier maybe had the humidity set too high. Look at your ceiling if you have shadow like marks where the wall meets the ceiling on every truss. You have too much moisture.

Post Your Comment
6/11/15 @ 3:47 PM
eyesman
eyesman
USER since 1/7/02
The stain is likely the effect of moisture condensation. The new AC unit is likely more efficient and produces more cold air than before, this cold air in turn creates a cold spot in the duct work and diffuser then attracting the moisture which pools, drips or runs creating the stain mark. The stain is more cosmetic than harmful. Once the moisture levels in the house are under control the staining should subside.

Post Your Comment
6/11/15 @ 2:34 PM
Cold Front
Cold Front
USER since 7/9/01
Flex duct. Mrt

Post Your Comment
6/11/15 @ 2:10 PM
fishfillet
fishfillet
USER since 1/8/13
duct cleaning is bs. also, a dirty air filter just makes the system work harder. it shouldn't stain the wall. usually staining has to do with moisture from something. do you have hard duct work or is it insulated flexible flex duct from the main to your room?

Post Your Comment
6/11/15 @ 2:03 PM
Cold Front
Cold Front
USER since 7/9/01
Yes, it is the diffusser. I did change the filter also. I will check if it washes away. It's only in one room. It looks like what you would expect if water was getting in but nothing feels wet. I took the cover off and stuck a tissue in there. I will see if it seems wet when I get home. This rain should help me figure this out. The spots appear to be getting a little bigger but it just started to rain. No wet feel to the areas.Could it be condensation from running the AC ? It was never a problem before. Mrt.

Post Your Comment
6/11/15 @ 12:18 PM
Budman
Budman
USER since 8/17/01
When you say "vents" do you mean the heating/AC diffusers feeding air into the room? If yes, did you try and see if you could wipe/wash the stain away? This could be nothing more than dirt from the air. How often do you change your furnace filter, and have you had the ducts cleaned. This "staining" is often caused by dust in your ducts.

Post Your Comment
Displaying 1 to 10 of 11 Posts