# How to seal an AC hole?



## kypper

I just had a central air unit installed and the installers drilled a large hole through the exterior wall to run the lines through. To fill this hole they used the same sealant putty used to seal around the lines into the duct. I don't think this is right. What is the proper way to seal this hole? I was thinking of using expanding foam and some caulk.


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## handy man88

Expanding foam and a silicon caulk should work, as you mentioned.


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## kypper

Thank you handy man88.


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## AtlanticWBConst.

Regarding spray foam, if you use the wrong type, it will absorb moisture. (I've seen it down that way and seen the foam turn into a sponge)

I know that there is this foam product rated to be weather tight and waterproof:

http://greatstuff.dow.com/greatstuff/diy/products/gc.htm


I would also suggest considering these points:

1.) If this is a hole in a wood material, to seal with a proper sized cedar or other durable type wood plug. Silicone any small crevices. Use exterior grade wood patch, exterior grade primer and paint to seal up.

2.) If this is in a concrete wall, I would suggest that you use hydaulic cement. 
It's beyond simple to use and can be shaped like putty, stuffed neatly and cleany into the hole and then smoothed out on each side for a permanant and water tight seal. The hole process would take you about 5 minutes to complete.

Both of these points leave an esthetically - more pleasing soluion.


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## kypper

I am going though vinyl siding and plywood sheating and then a joist sitting on the sill. It is funny you suggested greatstuff, it just happens to be what I had on my shelf. I was going to fill the hole with greatstuff, after it sets cut it flush with the siding, make a small patch out of vinyl siding, glue this patch to the siding, finish with caulk around the pipes to make is watertight. The only thing I need to figure out is what type of glue to use. I want to find one that will fuse the siding together similar to PVC pipes. Can I use PVC cement? If anyone has any suggestions please share.

Thank you for the advice Atlantic. I wish the hole was though cement, it sounds alot easier to do.


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## AtlanticWBConst.

kypper said:


> I am going though vinyl siding and plywood sheating and then a joist sitting on the sill. It is funny you suggested greatstuff, it just happens to be what I had on my shelf. I was going to fill the hole with greatstuff, after it sets cut it flush with the siding, make a small patch out of vinyl siding, glue this patch to the siding, finish with caulk around the pipes to make is watertight. The only thing I need to figure out is what type of glue to use. I want to find one that will fuse the siding together similar to PVC pipes. Can I use PVC cement? If anyone has any suggestions please share.
> 
> Thank you for the advice Atlantic. I wish the hole was though cement, it sounds alot easier to do.


Polyurethane glue (''Gorilla Glue''), PVC glue (cement), Composite trim glue.....


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## harleyrider

kypper said:


> I just had a central air unit installed and the installers drilled a large hole through the exterior wall to run the lines through. To fill this hole they used the same sealant putty used to seal around the lines into the duct. I don't think this is right. What is the proper way to seal this hole? I was thinking of using expanding foam and some caulk.


 
The people that installed your A/C do it everyday (I hope, unless you hired backyards bills to put it in) I am sure what they used is right even if YOU feel its wrong..........trained pro's know what they are doing.


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## coolmen

I use clear silcone on all my holes. Foam looks messy and may not be waterproof..


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## AtlanticWBConst.

coolmen said:


> I use clear silcone on all my holes. Foam looks messy and may not be waterproof..


 
Actually, this product is rated as waterproof:

http://greatstuff.dow.com/greatstuff/diy/products/gc.htm

However, I agree with you about the messy look.


I would also suggest using an MP1 or MP2 - like a SIKA product, if this is an HVAC line that producees moisture/condensation....


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## harleyrider

coolmen said:


> I use clear silcone on all my holes. Foam looks messy and may not be waterproof..


 
Clear silicone (100%) Is the standard in the industry.


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## kypper

harleyrider said:


> The people that installed your A/C do it everyday (I hope, unless you hired backyards bills to put it in) I am sure what they used is right even if YOU feel its wrong..........trained pro's know what they are doing.


 
There is no way that the way they left it was right. When standing in my basement I saw daylight around the pipes. When I looked closer there were holes large enough to let insects and spiders in, not to mention water. What they did was drill one large 2 1/2" hole. The 1 1/2" O.D. insulated line, 1/2" or so O.D. line and thermostat wire were the only items running though this hole, so you can imagine the amount of open space around the pipes. They used some sealant putty similar to plumbers putty, it may have been plumbers putty for all I know, to try to seal the hole. I would have rather seen two holes drilled just slightly larger than the pipes they ran. Thank you all that posted.


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## harleyrider

Sounds like you hired a sub par contractor..........call them back and make them do it right!


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