# How powerful a wet/dry vac is needed to suck out a clog in an Air Conditioner drain pipe? **URL:** \ **Category:** Factual Questions\ **Created:** [August 30, 2010, 10:49pm UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052 "2010-08-30T22:49:08Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [August 30, 2010, 10:49pm UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/1 "2010-08-30T22:49:08Z")
I was at Home Depot today and wasn’t sure how powerful a vac I needed. Probably not very powerful, but I wasn’t sure. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [August 30, 2010, 10:58pm UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/2 "2010-08-30T22:58:17Z")
Are you talking about an Air Conditioner? Why would you use a shop vac? Use a coat hanger. ---
**Author:** ![Mr.Accident](https://avatars.discourse-cdn.com/v4/letter/m/f05b48/32.png) [@Mr.Accident](https://boards.straightdope.com/u/Mr.Accident)\ **Post date:** [August 30, 2010, 11:44pm UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/3 "2010-08-30T23:44:09Z")
Can you disconnect the drain pipe? If so, one of [these](http://plumbing.hardwarestore.com/51-285-clog-busters/clog-buster-184689.aspx) might be a cheaper alternative to a wet/dry vac. It’s what I use to bust the rare clog in my ac’s drain pipe, since it’s to long for a coat hanger. ---
**Author:** ![Moonshiner](https://avatars.discourse-cdn.com/v4/letter/m/9fc29f/32.png) [@Moonshiner](https://boards.straightdope.com/u/Moonshiner)\ **Post date:** [August 30, 2010, 11:53pm UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/4 "2010-08-30T23:53:42Z")
When I worked for an HVAC (no slash in there) contractor the techs used a little gizmo with a CO2 cartridge to blow the clogs out. An air compressor would probably work too. Be sure to block off all outlets except the exterior one. ---
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [August 31, 2010, 12:34am UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/5 "2010-08-31T00:34:25Z")
> [@TriPolar](#): > > Are you talking about an Air Conditioner? Why would you use a shop vac? Use a coat hanger. The line goes from my attic to the outside, and the clog is somewhere in between. Doubt a coat hanger will reach. ---
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [August 31, 2010, 12:35am UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/6 "2010-08-31T00:35:35Z")
> [@Mr.Accident](#): > > Can you disconnect the drain pipe? If so, one of [these](http://plumbing.hardwarestore.com/51-285-clog-busters/clog-buster-184689.aspx) might be a cheaper alternative to a wet/dry vac. > > It’s what I use to bust the rare clog in my ac’s drain pipe, since it’s to long for a coat hanger. No, but thanks for the suggestion. ---
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [August 31, 2010, 12:38am UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/7 "2010-08-31T00:38:39Z")
> [@Moonshiner](#): > > When I worked for an HVAC (no slash in there) contractor the techs used a little gizmo with a CO2 cartridge to blow the clogs out. An air compressor would probably work too. Be sure to block off all outlets except the exterior one. Well, if I have to buy something, a wet dry vac will probably get the most use. ---
**Author:** ![unclelem](https://avatars.discourse-cdn.com/v4/letter/u/ac91a4/32.png) [@unclelem](https://boards.straightdope.com/u/unclelem)\ **Post date:** [August 31, 2010, 1:49am UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/8 "2010-08-31T01:49:31Z")
I’ve had good luck with a cheap lightweight plumbing snake in the past. Much cheaper than a wet/dry vac, and likely to see more use. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [August 31, 2010, 1:56am UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/9 "2010-08-31T01:56:07Z")
Have you tried just taking the hose off the evaporator and blowing through it? There’s a good chance it’s just a bunch of muck and slime in there. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [August 31, 2010, 1:57am UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/10 "2010-08-31T01:57:30Z")
I have a mid-range shop vac and it just doesn’t generate that much vacuum. It doesn’t have to. The suction needed to pull water or dust or dirt from a floor is quite different than what you need to suck out a clog (depending on the clog). There’s no guarantee that the most powerful vac at Home Depot will do it. Plumbers use snakes, not vacuums. Now, if you think you might want a shop vac anyway, get one and try it. Then get a snake if it doesn’t work. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [August 31, 2010, 2:00am UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/11 "2010-08-31T02:00:55Z")
Just saw that you said you can’t disconnect it (why not?) I think pretty much any shop vac will put out a clog. Just make sure you get a good seal between the drain hose and the vac hose. Might take some Macgivering to rig something up. Maybe wrapping a damp towel around the drain hose to mike it closer in size to the vac hose. If it’s a complete blockage, even a small vacuum is going to create a lot of negative pressure inside the drain hose. Between that and the weight of the column of water above the cog and I think it’ll pop it right out. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [August 31, 2010, 3:39am UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/12 "2010-08-31T03:39:52Z")
Power and the amount of vacuum pulled by a vacuum are not necessarly related. So pick the size you want. You may be able to clear the drain with a vac, just try and get a good seal. ---
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [August 31, 2010, 12:47pm UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/13 "2010-08-31T12:47:15Z")
> [@Joey\_P](#): > > Have you tried just taking the hose off the evaporator and blowing through it? There’s a good chance it’s just a bunch of muck and slime in there. > [@Joey\_P](#): > > Just saw that you said you can’t disconnect it (why not?) > I think pretty much any shop vac will put out a clog. Just make sure you get a good seal between the drain hose and the vac hose. Might take some Macgivering to rig something up. Maybe wrapping a damp towel around the drain hose to mike it closer in size to the vac hose. > If it’s a complete blockage, even a small vacuum is going to create a lot of negative pressure inside the drain hose. Between that and the weight of the column of water above the cog and I think it’ll pop it right out. I can’t disconnect it because it’s all sealed PVC pipe, but there it a spot with a removable sensor that is supposed to turn off the unit when it detects there’s water from a clog (but doesn’t work). I have been able in the past to blow into that to clear clogs, but that isn’t working now. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [August 31, 2010, 1:28pm UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/14 "2010-08-31T13:28:08Z")
Whether or not a vacuum would work depends largely on how “stuck” the clog is. A perfect vacuum on one side and atmospheric pressure on the other side gives ~15 psi pressure differential, which isn’t much compared to other methods. I’d be surprised if the vacuum did the job. ---
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [August 31, 2010, 2:02pm UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/15 "2010-08-31T14:02:13Z")
When I googled about clogged ac drain lines, I found several suggestions to suck it out with a wet dry vac. It seems to be a fairly common way to solve this problem, unless people are suggesting it without actually trying it first. ---
**Author:** ![BubbaDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bubbadog/32/333_2.png) [@BubbaDog](https://boards.straightdope.com/u/BubbaDog)\ **Post date:** [August 31, 2010, 3:27pm UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/16 "2010-08-31T15:27:18Z")
I got nothing to add other than a slight hijack about how relieved I was to discover that I misread your question about needing to suck a **DOG** out of a drainpipe. ---
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [August 31, 2010, 4:59pm UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/17 "2010-08-31T16:59:32Z")
> [@BubbaDog](#): > > I got nothing to add other than a slight hijack about how relieved I was to discover that I misread your question about needing to suck a **DOG** out of a drainpipe. I assume it’s algae, but won’t know for sure until I get it out. I haven’t seen my Pomeranian for a while now, hmmm… ---
**Author:** ![Mtgman](https://avatars.discourse-cdn.com/v4/letter/m/b5a626/32.png) [@Mtgman](https://boards.straightdope.com/u/Mtgman)\ **Post date:** [August 31, 2010, 5:42pm UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/18 "2010-08-31T17:42:42Z")
I had a clog in my drain pipe last week and was able to clear it with [my shop vac](http://www.homedepot.com/Tools-Hardware-Wet-Dry-Vacuums/h_d1/N-5yc1vZ1xggZb8pi/R-202198493/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053). It worked fine, and it let me clean up the crawlspace under the unit where it had leaked too. Algae buildup can be cleared and then you can run a bleach flush by pouring it in slowly followed by a water flush. If you have a secondary drain(some units do, some don’t) you can get a flexible funnel, open the drain and pour some bleach in through it, let it sit in the collector pan for a couple minutes, then follow it with a water flush. Enjoy, Steven ---
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [August 31, 2010, 8:33pm UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/19 "2010-08-31T20:33:58Z")
> [@Mtgman](#): > > I had a clog in my drain pipe last week and was able to clear it with [my shop vac](http://www.homedepot.com/Tools-Hardware-Wet-Dry-Vacuums/h_d1/N-5yc1vZ1xggZb8pi/R-202198493/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053). It worked fine, and it let me clean up the crawlspace under the unit where it had leaked too. Algae buildup can be cleared and then you can run a bleach flush by pouring it in slowly followed by a water flush. If you have a secondary drain(some units do, some don’t) you can get a flexible funnel, open the drain and pour some bleach in through it, let it sit in the collector pan for a couple minutes, then follow it with a water flush. > > Enjoy, > Steven That was one of the ones I looked at yesterday at home depot for this task, thanks for confirmation that this model did the trick for at least one person. I’m going borrow one from a friend today, but if that doesn’t work out for whatever reason I’ll likely pick that one up. What is the output of your drain that you attached this to, PVC? How did you get a tight fit? Did you use one of the included attachments, or what? ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [September 1, 2010, 1:18am UTC](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052/20 "2010-09-01T01:18:17Z")
> [@Joey\_P](#): > > Have you tried just taking the hose off the evaporator and blowing through it? There’s a good chance it’s just a bunch of muck and slime in there. This. Unless you have insects building a nest it is most likely muck and slime which can be blown out. If you truly want a wet vac anyway then I would suggest one l[ike this](http://www.shopvac.com/vacs/detail.asp?ID=125&HdnSource=index&StoreID=) with a detachable leaf blower. You’ll have to duct tape the hose to the drain outlet to get a good seal on it. [Next page](https://boards.straightdope.com/t/how-powerful-a-wet-dry-vac-is-needed-to-suck-out-a-clog-in-an-air-conditioner-drain-pipe/552052.md?page=2)