Commenting before I finish you’re video. But I do residential HVAC just south of you, we were having tons of ventilated attic that didn’t have shield tec sheathing with ducts sweating. It was a nightmare for a few weeks
Even vented attics can have ducts sweat due to extremely high dewpoints during the recent tropical storm. The best was to fix it is very expensive- an encapsulated attic, or more ventilation in the attic. Not attic exhaust though! Just moving air within the attic.
Another great video! This is a hot topic on HVAC-Talk right now. Interesting how some people are following your idea (and the extended version from the video you recommended to me in the other video), and the others think the exact opposite idea is the way to solve the sweating duct issue. Thanks again for taking your time to teach! As a side note, the auto CC on your videos (I know it's not in your control) is interesting..."ducks" for ducts, and "HBC" for HVAC, amongst others.
The only thing I would say about this video is….. most codes require a minimum of R8 insulation in unconditioned spaces. Other than that, this information is gold!
Hey Tim great video as always. Is there a resource/Calc to calculate the surface temperature of the duct depending on the SA, attic temp/RH, duct R valve?
I asked him that (I think) last week. I did find a calculation but it has a few problems. Trying to find the actual inner film and outer film R-Values, and it doesn't account for radiant gain, which is really hard to calculate. So if you found the correct inner/outer R-values, in an attic, the surface temp calc would only calculate the bottom of the duct surface (not getting hit by radiant gain). What I think might be easiest, is simply one psychrometer in the duct, one in the space, and a k-type thermocouple slipped through a slot in the insulation and stuck to the duct itself gives you the information that you need to decide on a solution that Tim recommends.
Have a non spray foam attic with lay in bats insulation. All the ducts are sealed pretty well. Supply ducts are water logged. Besides letting them know not to set the tstat to 40% humidity at 71° would recommending an attic dehumidifier be a good idea?
@@TrillasTexas no attic dehu unless its encapsulated. Ducts need to be R8. Attic needs even more ventilation. Get the ducts out of the blown insulation.
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Commenting before I finish you’re video. But I do residential HVAC just south of you, we were having tons of ventilated attic that didn’t have shield tec sheathing with ducts sweating. It was a nightmare for a few weeks
Even vented attics can have ducts sweat due to extremely high dewpoints during the recent tropical storm. The best was to fix it is very expensive- an encapsulated attic, or more ventilation in the attic. Not attic exhaust though! Just moving air within the attic.
Another great video! This is a hot topic on HVAC-Talk right now. Interesting how some people are following your idea (and the extended version from the video you recommended to me in the other video), and the others think the exact opposite idea is the way to solve the sweating duct issue.
Thanks again for taking your time to teach!
As a side note, the auto CC on your videos (I know it's not in your control) is interesting..."ducks" for ducts, and "HBC" for HVAC, amongst others.
@@HVAC_Tips_Tricks_Calcs i should fix the cc but Im lazy
@@timdestasiohvac lol…
The only thing I would say about this video is….. most codes require a minimum of R8 insulation in unconditioned spaces. Other than that, this information is gold!
@@anthonydesimone8308 yes but they didnt always. Theres alot of r4 and r6 ducts out there from 20-50 years ago.
Hey Tim great video as always. Is there a resource/Calc to calculate the surface temperature of the duct depending on the SA, attic temp/RH, duct R valve?
I asked him that (I think) last week. I did find a calculation but it has a few problems. Trying to find the actual inner film and outer film R-Values, and it doesn't account for radiant gain, which is really hard to calculate. So if you found the correct inner/outer R-values, in an attic, the surface temp calc would only calculate the bottom of the duct surface (not getting hit by radiant gain).
What I think might be easiest, is simply one psychrometer in the duct, one in the space, and a k-type thermocouple slipped through a slot in the insulation and stuck to the duct itself gives you the information that you need to decide on a solution that Tim recommends.
@@ajbeck2121 search of youtube hvac school.conductsation. a great seminar by rick sims.
Have a non spray foam attic with lay in bats insulation. All the ducts are sealed pretty well. Supply ducts are water logged. Besides letting them know not to set the tstat to 40% humidity at 71° would recommending an attic dehumidifier be a good idea?
@@TrillasTexas no attic dehu unless its encapsulated. Ducts need to be R8. Attic needs even more ventilation. Get the ducts out of the blown insulation.