# Will air turbulence in flexible airduct causes water condensation?

• A
• LMC
In summary,1. Condensation can happen at the bended flexible airduct due to air turbulence.2. The temperature increased at the air turbulence area due to decreased air flow, but it will not be high enough to cause condensation.3. If yes, how high can it be? Will temperature raises so high that the Tdewpoint at this turbulence point = 23deg.C (the air that flow next to the turbulence) and caused condensation?
LMC
In a normal aircond system using flexible airduct, assume airflow with temperature & humidity conditions (Tdry=23°C; Tdew=13.4°C; RH=55% ) go through a bended flexible airduct where air turbulence is formed:
1. Can condensation happens at the bended flexible airduct due to air turbulence?
2. Will the temperature increased at the air turbulence area due to decreased air flow?
3. If yes, how high can it be? Will temperature raises so high that the Tdewpoint at this turbulence point = 23deg.C (the air that flow next to the turbulence) and caused condensation? 4. Under what condition change will water condensation at the bended flexible duct happens and accumulate water? For how long?

LMC said:
In a normal aircond system using flexible airduct, assume airflow with temperature & humidity conditions (Tdry=23°C; Tdew=13.4°C; RH=55% ) go through a bended flexible airduct where air turbulence is formed:
1. Can condensation happens at the bended flexible airduct due to air turbulence?
2. Will the temperature increased at the air turbulence area due to decreased air flow?
3. If yes, how high can it be? Will temperature raises so high that the Tdewpoint at this turbulence point = 23deg.C (the air that flow next to the turbulence) and caused condensation? 4. Under what condition change will water condensation at the bended flexible duct happens and accumulate water? For how long?
1. No.
2. Very little.
3. No.
4. Location of bend is low and water is being carried away from thecolling coil or condensate pan. Perhaps too much humid fresh air is entering the system and relative humidity is much higher than assumed for that temperature (the coil is unable to condensate some of it due to high velocity or few rows or refrigerant temperature).

There is turbulence in the blower and the whole duct system.

russ_watters and 256bits

In another word, is my understanding correct that only when there's an increase in moisture content (at/almost near dew point temperature) inside the airduct that condensation will happen, regardless of straight/bended airduct?

LMC said:
2. Will the temperature increased at the air turbulence area due to decreased air flow?
3. If yes, how high can it be? Will temperature raises so high that the Tdewpoint at this turbulence point = 23deg.C (the air that flow next to the turbulence) and caused condensation?
#2 is yes, a little, but #3 is backwards. The [dry bulb] temperature goes up, but the dew point stays the same. So it decreases the chance of condensation, not increases.

Lnewqban
russ_watters said:
#2 is yes, a little, but #3 is backwards. The [dry bulb] temperature goes up, but the dew point stays the same. So it decreases the chance of condensation, not increases.

LMC said:

In another word, is my understanding correct that only when there's an increase in moisture content (at/almost near dew point temperature) inside the airduct that condensation will happen, regardless of straight/bended airduct?
You are welcome.
A surface, which remains cooler than the air, is needed for abundant condensation to happen.
The insulation of that flex duct should avoid the heat transfer or energy loss, that a massive flow of cool air needs to reach the condensation point.

Because of that, I believe that water is finding its way into the duct layout somehow.
In Florida, it is common to find internal mold growth a few feet away from the coil in commercial installations, mainly due to splashing.
One case, had a pipe leak dropping on top of a metal duct, and water was finding its way inside the insulation and duct, via leaky seams: mold was growing inside that section only.

russ_watters said:
#3 is backwards. The [dry bulb] temperature goes up, but the dew point stays the same. So it decreases the chance of condensation, not increases.
Hi russ_watters, is my understanding correct that dew point stays the same because moisture content remains the same?

russ_watters
LMC said:
Hi russ_watters, is my understanding correct that dew point stays the same because moisture content remains the same?
Yep! Dew point is a direct function of just moisture content. Unlike relative humidity which is a function of moisture content and temperature.

Lnewqban
https://web.ornl.gov/sci/buildings/conf-archive/2007 B10 papers/010_Morse.pdf

https://www.engineeringtoolbox.com/humidity-measurement-d_561.html

https://www.practicalhvac.com/uncategorized/the-psychrometric-chart/

Last edited:
russ_watters

## 1. Will air turbulence in flexible airduct cause water condensation?

Yes, air turbulence in flexible airduct can cause water condensation. When air flows through a flexible airduct, it can create turbulence, which causes the air to mix and cool down. If the air is cooled below its dew point, water vapor in the air can condense and form droplets.

## 2. How does air turbulence in flexible airduct lead to water condensation?

Air turbulence in flexible airduct creates areas of low pressure and high pressure, causing the air to mix and cool down. As the air cools, its ability to hold water vapor decreases, leading to the formation of water droplets.

## 3. Is water condensation in flexible airducts a common problem?

Yes, water condensation in flexible airducts is a common problem, especially in areas with high humidity. It can occur in both residential and commercial buildings, and can lead to issues such as mold growth and damage to the airducts.

## 4. How can we prevent water condensation in flexible airducts?

To prevent water condensation in flexible airducts, it is important to properly insulate the airducts to prevent them from being cooled by the surrounding air. Additionally, maintaining proper air flow and humidity levels can help reduce the chances of condensation occurring.

## 5. What are the potential consequences of water condensation in flexible airducts?

Water condensation in flexible airducts can lead to several consequences. It can cause damage to the airducts, leading to decreased efficiency and potentially costly repairs. It can also create a breeding ground for mold and bacteria, which can have negative effects on indoor air quality and pose health risks to occupants.

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