HVAC-Talk: Heating, Air & Refrigeration Discussion banner

Condensation and mold on 24 ft vaulted ceilings all of a sudden

693 views 9 replies 9 participants last post by  Genius.  
#1 ·
I am located in Central NC and we have a 3200 square ft building that is one large open room. We have vaulted ceilings that are 24 ft at the peak. We have four 3 ton LG mini splits that are mounted about 10 ft from the floor and cool the space with no issues. This has been set up for almost 5 years and has been great. Today we just noticed water dripping from the ceiling. We have a scissor lift so I went to investigate and found that the peak of the ceiling and about 5 ft down from the peak had condensation and mold in several spots. The ceiling is a dark stained wood tongue and groove, so it was not easy to spot the mold right away. The room stays nice and cool and I am able to keep the temperature pretty much where I need it, even with 200 guests. It is much hotter above 12 ft and even hotter at the peak, but this has never changed was always this way. The question is can anyone explain why all of a sudden we would have this condensation and mold? Do I need some type of ventilation for the area above the mini splits?
 
#2 ·
Humidity % in room?
Normal temperatures?
Condensate drain lines clear?
Couple of ceiling fans would probably help & maybe a dehumidifier.
 
#4 ·
Monitor the temperature/%RH in the area above and below the ceiling. You will see where the problem is. When fully occupied, you may reach the dew point of the ceiling. It also depends on the temperatue/%RH of the space above the ceiling.

Over cooling in either area could cause the problem.

Keep us posted.

Regards Teddy Bear
 
  • Like
Reactions: R600a
Save
#5 ·
Probably, your ceiling surfaces are colder than the dew point of the air in the space above above the ceiling. Measure the temperature/%RH/^F dew point of the air on both side of the ceiling material. As outdoor weather changes during the season, the air dew point in the air between roof and room ceiling rises and declines. Outside air moisture migrates to the cooler surfaces of the under roof air to the point where condensation wets the surface continuously and mold grows.

Tell us the temp/%RH of the air on top and bottom of the ceiling materials. Describe the ceiling materials like drywall, insulation, and vapor barrier. Warm the space temperature a couple degrees will lower condensate rate. Mold will not grow with moisture. You may also be getting a buildup of moisture in the space above the ceiling insulation. Short term, warm the occupied space side as much as possible, especially evenings when the roof cools. The conditions will change rapidly with minor temperature/%RH reductions on two side of the ceiling.

This is serious problem that will affect sensitive occupants.

Get the info and we will comment.

Regards Teddy Bear
 
Save
#6 ·
Is it possible the roof is leaking?

We havnt had a lot of rain lately, but humidity has climbed with the shorter days and, of course the last two days of rain we hav had sprinkle us.
 
#8 ·
Tongue and groove boards are NOT an air barrier. Some sort of barrier has to be installed above the boards or there will be lots of infiltration.
During a blower door test of a house, the air could be heard whistling through the ceiling of the room with a T&G ceiling.
Air from above The ceiling is hot, dirty, and loaded with moisture. It must be kept out of the living space.
 
  • Like
Reactions: vstech and R600a
Save
You have insufficient privileges to reply here.