ducts leaking


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Old 07-01-12, 08:22 AM
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ducts leaking

hello,

i have a older home with a crawl space, which is where my ac unit is located. I have a couple questions that i hope you all can help me with. first off let me say that it is cooler in the crawl space than it is in the house. also a little bit about my system, it has the main part, the part where the ducting id connected, the the ducting is flexible shiny metal that goes to the floor vents. My questions are as follow: first can the main part be leaking? if so how do i test and fix? should i caulk or put something on it to seal it? second, the type of ducting i have is it good or should i switch to something else?

any help would be great...thanks in advance!
 
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Old 07-01-12, 10:36 AM
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The seams of all the ducts can be taped with an aluminum foil faced tape. This will eliminate air leakage at all the seams.

Your main ductwork can be insulated with r-6 fiberglass wrap, and those seams can be taped. Individual runs can be wrapped with duct wrap insulation. The purpose of these is to prevent condensation and to ensure that the cold air is reaching its destination. Ducts that are not insulated will lose more heat/cold than those that are not insulated.
 
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Old 07-01-12, 05:10 PM
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ok, i will tape all the seams. I have the flexible duck work under my house. is this ok or should i try to get the rigid duck work? Also just to make sure i am following what was said above, at the main part of the ac unit that is in my crawlspace i should wrap that in insulation as well, right? also on the main part where all the ducks are coming off there are places that look like it has some type of sealant on it and it has been painted on? does this sound correct and can i use some of that to seal instead of the tape? what is that called?
 
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Old 07-01-12, 05:42 PM
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They probably painted mastic onto the sheetmetal joints. You could use that again, but if they used it once and the joints cracked open... they will probably pop open again. And if you are unsure about what type of insulation to use around the ducts, just google duct insulation wrap... duct, not duck. "Duck" is a brand.
 
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Old 07-01-12, 07:10 PM
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ok thanks...i will google it...also what temp should the air be coming out of the vents in the house? and should the crawlspace be cool or hot when all is correct under the house?
 
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Old 07-01-12, 07:27 PM
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Crawlspaces are usually cool... your ground temps there are probably 60-65F, depending, so a lot of the cool air can come from that. The temperature of the conditioned air coming out of your ducts depends on a few things... first, the condition of your A/C... the condition of the ducts... and the temperature of the return air going into the a-coil. Usually you want to see a 15-20F temperature differential between return and supply air. So if the return air is 74F... 58F air coming out would be great... something in that neighborhood.

Also you might google r-6 duct insulation wrap just to be sure you are looking at the stuff I was suggesting for wrapping your metal ductwork. I forgot the r-6 part.
 
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Old 07-02-12, 05:55 AM
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Ok, as far as the unit it is about 3 or 4 years old. The ducts have been there since before i moved in which was about 6 years ago. I will check the vents today and ducts today. I asked about the temp because it has been hot the last couple days up to 104 each day and the ac cannot keep up, it has gotten to where it will get all the way up to 80 degrees in the house. The unit is a 3 ton unit and my house is 1300 square feet? If the vents are fine or after i fix them what else can be wrong? Also it dont seem as if it is blowing hard out the vents? Can i get a booster fan of some sort?
 
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Old 07-02-12, 11:25 AM
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ok so i went under the house and there were no duct leaks...yay...but i did find that the drain is leaking? i will attach 2 pics...So, is this normal or ok? What would cause it to leak and not just drain. I can say that I went to the end of the drain pipe and water is draining out of the end of the pipe but it is also leaking out of the box as well. I hope that this is not a major problem but if it is can you tell me how to fix it?
 
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Old 07-02-12, 03:44 PM
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I'm not a professional HVAC guy so I can't answer your questions about unit sizing. But as for the leak, I can't really tell you how to fix it- is it coming out of the pan or out of the pipe or what? If water is still draining out the pvc drain pipe, then maybe your pan has sprung a leak and needs to be gooped up some more. If no water, or very little water is coming out the pvc pipe it could be plugged up. You'd need to cut the pvc, (have a pvc coupling and glue so you can put it back together when ur done) and hose the pan out because it could be crudded up. You will also want a 5 gallon bucket to catch some of the water. If you are going to go to all that trouble you also could wash off your a-coil, which should be located near that leak as well. If the a-coil is dirty that can also affect the efficiency of the unit.

Sometimes when people neglect to change their furnace filters it will make the a-coil and condensate pan really dirty.

If this is located someplace where it can't/shouldn't get wet or it's over dirt and you just don't want to slosh around in mud, buy one of those plastic baby wading pools and put it down where it will catch the rinse water.

That's about the best I can do.
 
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Old 07-02-12, 04:56 PM
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yeah that is what i was thinking...it is coming out of the pan so i guess the pan has sprung a leak...i have never delt with anything like this but i guess there is always a first time for everything. Do you know how the pan may come off or how to get into it to clean it andthe coil? how do i clean the coil? is there anything i need to spray on it or use a brush or what? I am pretty handy so i dont mind trying something...
 
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Old 07-02-12, 05:37 PM
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It's not possible for me to know how it was put together, because each unit like that is usually custom metal ductwork created by the HVAC company who installed it. But if you examine the seams you might be able to tell which side panel was put on last and is usually meant to be taken apart. Look for a few 1/4" hex zip screws on both sides of one panel.

As for cleaning the a-coil, you could spray on something like 409, or mix up some TSP, to spray on first. But generally water and a trigger sprayer is all that is needed to rinse the dirt off, unless yours is completely plugged. Then a soft brush, like a toilet bowl brush, might be needed.

For repairing the pan leak, the stuff I like to use for such repairs is made by Geocel and its called Watershield brushable sealant, (Geocel Pro Flex brushable is basically the same product) it comes in a quart can. It's not meant to fill large holes since it is a thick liquid. So if there are large gaps you might want to caulk them first with Geocel Watershield caulking which you could tool into the gaps/joints, then pour some of the brushable sealant over the top of it and brush it around a little. It's self levelling and won't cure very fast if you put it on too thick- it's meant to be brushed on in thin coats. Read the instructions carefully to see if you need the surfaces to be dry when you do this.

When you go to reassemble, rather than coating the edges of the removable panel with mastic or Geocel, I'd use the foil tape. It sticks like glue and is easy to slice through if you need to open it up again someday down the road.

When checking for air leaks, something that's great to use is one of the punks that they are selling right now to light firecrackers. Incense sticks also work well. Just let the smoke drift past the joint and if there is a leak you'll see the smoke set sail. Just don't burn ur house down with them. lol
 
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Old 07-03-12, 11:33 AM
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thanks for all the advise you have really helped me out. I took the drain line off and figured out that it was plugged up a little so i used some air and blew it out...reattached the drain and it seems to be draining all through the pipe. I will keep an eye on it for a couple days and if it starts to come out of the pan again then i guess i will get into it as you have said. thanks once again and i will keep you posted
 
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Old 07-03-12, 03:14 PM
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Sounds great. It was probably holding a lot of excess water.
 
 

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