Duct insulation installation questions/ condensation.

[jayfrank5074]

My house was built in 1961. It has a package heat and ac unit. 4 ton.

The duct work is in the crawl space. There is a main branch running from the unit to the center of the house, then shaped like a T. I’d guess this T is 70ft total.

Off the T is round flexible duct.

The “T” isn’t insulated and sweats a lot.

I think I’d like to insulate it. What insulation is recommended? I see foam sandwiched between foil, and regular fiberglass listed(foil on one or maybe both sides)

The round flexible duct has very little condensate dripping. The T looks like a rain Forest.


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[jayfrank5074]

<a href="https://ibb.co/ZNMMGM2"><img src="https://i.ibb.co/8X77N7Y/1-E8-E21-ED-9938-49-EE-A814-D904-E43675-B0.jpg" alt="1-E8-E21-ED-9938-49-EE-A814-D904-E43675-B0" border="0"></a><br /><a target='_blank' href='https://imgbb.com/'>picture hosting</a><br />


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[jayfrank5074]

<a href="https://ibb.co/JmPNGn0"><img src="https://i.ibb.co/tQ5SvBk/287811-F4-7-F73-4-E4-F-A590-331421522-CAD.jpg" alt="287811-F4-7-F73-4-E4-F-A590-331421522-CAD" border="0"></a>


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[jayfrank5074]

Click on first pic and see the right side. I crawled under the part in the thumbnail.


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[marietteachrist]

How much is the capacity of your room to fit the ductile.

 

[jayfrank5074]

How much is the capacity of your room to fit the ductile.

Not sure what you are asking.


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[anythingyoucanimagine]

Not sure what you are asking.

I believe that means what size is the room or what does the room require to heat/cool it. Your pictures are showing up as html code and links are 404'ing.

 

[jayfrank5074]

I believe that means what size is the room or what does the room require to heat/cool it. Your pictures are showing up as html code and links are 404'ing.

This duct work is for the whole house. It’s been installed for roughly 20 years that I know of. Ive been there for ten and the previous unit was 8-10 years old when we moved in.

All the picture shows is a square duct that has a lot of water dripping off of it. The flexible ducts have almost no condensate dripping off them.


My question is about insulation. I’m wondering what kind to use and any tips installing.


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[jayfrank5074]

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[Higgins]

What is the humidity level in that area?

You may have several issues that need to be addressed!

AL

 

[jayfrank5074]

What is the humidity level in that area?

You may have several issues that need to be addressed!

AL

I live in the southeast. Humidity is always high pretty much.

What would the other issues be? Air runs all day this time of year.


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[jayfrank5074]

Humidity is 88% outside right now.


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[Higgins]

The first would be the high humidity causing the heavy condensation. wrapping the duct work with an insulated blankets would resolve.

There are conditions where AC units run for extended periods of time and even with low levels of humidity the Plenum will sweat just due to the metal being so cold in relation to surrounding area. Again adding insulation to the plenum resolves this condition.

 

[metlmunchr]

Chances are the house didn't have a/c originally and when it was added later it was done without insulating the ductwork. Uninsulated ducts on heat only systems was fairly common in the south during that time due to the fact that energy was cheap, and a very small percent of houses built in that era had central air.

Wrapping the ducts will take care of the problem. Fiberglass duct wrap is what you want, and not any of the other hocus pocus bubble wrap or barrier wrap or any other sort of similar junk currently promoted as insulation.

If it were my system, I'd hire an insulation contractor whose business is duct and piping insulation to do the job. Their people do this sort of work every day, as opposed to people who work for a hvac contractor and may do a duct wrap job once a month (and typically do it very poorly).

Or, if you're a real glutton for punishment, you could do it yourself, but, chances are you'll wish you'd hired it done by the time you finish 1/4 of the job. Its very difficult for one person to do a proper job, and wallowing in glass fibers makes for miserable working conditions.

 

[jayfrank5074]

Thank you both so much for the replies.

I really don’t care if the water drips off, but I am having moisture problems under the house, I figure that rain forest would be a good place to start. Any more tips?

Plastic on the ground?

Encapsulate and condition the space?



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[SGKent]

is the underside of the house exposed to the outside or is it a sealed area? You may have to lower moisture under the house differently for each. Example, if the soil level has changed and water is no longer draining away from the house then you have to correct that issue. If the water table is high and the moisture is coming up you may need to deal with that. If it is a sealed area you may have to put in a dehumidifier. The HVAC has to be insulated to where no air can reach it or the moisture will get trapped under or in the insulation.

 

[jayfrank5074]

The underside is open, we have hardwood floors and you can see the subfloor.
I think the water table is probably high. It’s rained a lot this year and last(last was a record).
I haven’t changed any soil levels.
So if the water table is high, the way to combat that is to put plastic down? I am thinking of putting 10mil down and taping and mastic the plastic to the cinder blocks and pillars. IE trying to seal it up pretty good.

So for sure I need to contact someone about insulating the duct work.

The branches off the “T” are insulated flex duct, very little condensate dripping off of them.

I do have to wonder how this is suddenly a problem, the duct work has been there for sure the 10 years we have been there. I really think its been there about 20 years.

I will say my wife is a stay at home mom for the next few years so the house stays cooler in the day than when she had a job.


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[SGKent]

the soil levels on any home changes over time. Be sure that the gutter drains are dumping water away from the house and that no water is running back towards the house. Dig a small hole in the ground under the house away from the condensation. See if the soil six inches to a foot deep is dry or wet. That will tell you if the problem is from below I think. I don't know what would be a good fix for wet soil. Termites love damp soil so that is something you should be on the look out for too.

 

[jayfrank5074]

Dug holes, no problems seen. Tried two places, roughly 8” deep.

Saw moist dirt not near the ac ducts, I’ll look for water intrusion.

Gutters appear ok, need to look when it’s raining to verify.


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