Condensation on the air-conditioner vents?

[Wampuscat]

I have a New house that the air-conditioner vents in a number of our rooms have condensation forming them. It didn't do this last summer so I'm not sure what the problem is? Would any of you have any ideas because the air-conditioner guy is at a loss.

[Smithwr]

http://lmgtfy.com/?q=Condensation+on+home+ac+vents

[H-D]

My guess is that you are over on your tonnage.

[miket]

Im not a pro but condensation is caused by the temperature being lower than the dew point. So that means humidity is too high in the house or temp too low coming out of the vents. Too much humidity in the house is caused by not enough air changes, a/c too large for house, unusually high delta T. Too low temp out of vents is caused by too low air flow over coils. May be fan setting or sizing issue. Hopefully a pro will chime in.

[miket]

Does your thermostat show humidity level? Does it feel warmer in the house than than the temperature shows?

[SKLOSS]

Could also have to do with the installation of the vents. They need to be completely sealed/insulated from the attic air temps.


Oh look a fajita!!

[Gummi Bear]

Talk wih a real AC professional first. Make sure everything is operating ad it should, and the system is balanced (this will require a flow test, and possibly the installation of some dampers)

I'd make sure the boot is sealed to the sheetrock. Mastic is the proper material for this. It is a putty. You can apply it with a paintbrush or spatula. I find it just as easy to wear some nitrile gloves and use my fingers to apply it.

Remove the grill, and if there is a gap between the edges of the boot, and the sheetrock, fill this with mastic and let it dry.

Make sure you put the same grill back on the same boot, so you maintain the proper airflow.


When pressurized air is forced through the boot, it will suck hot air out of the attic through this gap. It causes condensation, and sucks in a bunch of dust to the house.


Sent from my iPhone using Tapatalk Pro

[Throwin Darts]

are any of those rooms near a bathroom?

[PNOAK]

check and make sure there is insulation in the attic around those vents,I had the same situation with a new house and come to find out they had "forgotten "to blow insulation on that side of the house.

[Ryan81]

Could also have to do with the installation of the vents. They need to be completely sealed/insulated from the attic air temps.


Oh look a fajita!!

This.

My vents did this last year. Taped up the flex ductwork and no more condensation.


Sent from my iPhone using Tapatalk

[dauphlp]

Could also have to do with the installation of the vents. They need to be completely sealed/insulated from the attic air temps.


Oh look a fajita!!

You are correct, I'm having one of my vents re-installed. Where the duct meets the vent cover is a small space and attic air is being pulled into the duct and out the vent into the room. This air is hot and has high humidity. When it hits the cool metal vent this humidity condenses on it.

[Rustythebeagle]

I moved into an older house and replaced all the vents. I started to see issues with black spores and condensate forming on all the vents. I removed all the vents and caulked and sealed around them however the problem returned.

I ended up replacing the metal vents with plastic vents and have had no issues with condensation or mold spores.

[JEG8233]

Talk wih a real AC professional first. Make sure everything is operating ad it should, and the system is balanced (this will require a flow test, and possibly the installation of some dampers)

I'd make sure the boot is sealed to the sheetrock. Mastic is the proper material for this. It is a putty. You can apply it with a paintbrush or spatula. I find it just as easy to wear some nitrile gloves and use my fingers to apply it.

Remove the grill, and if there is a gap between the edges of the boot, and the sheetrock, fill this with mastic and let it dry.

Make sure you put the same grill back on the same boot, so you maintain the proper airflow.


When pressurized air is forced through the boot, it will suck hot air out of the attic through this gap. It causes condensation, and sucks in a bunch of dust to the house.


Sent from my iPhone using Tapatalk Pro

X2

With this years hotter temps than last years a lot of these problems are magnified.

But as said above, you should start off with a qualified HVAC pro going through the entire system. This will verify if the unit is sized right and performing up to standards.

The next step of getting airflow checked and verified maybe a bit harder. Not all hvac companies can do it right, i.e. Flow good and manual J work up.

[Wampuscat]

Could also have to do with the installation of the vents. They need to be completely sealed/insulated from the attic air temps.


Oh look a fajita!!

The vents were caulked about 1 or 2 months ago when this happened last.

[Wampuscat]

are any of those rooms near a bathroom?

Yes but there are more throughout the house.