DIY Home Improvement, Remodeling & Repair Forum > Appliances > HVAC > AC drain pipe question

Thread Tools Search this Thread Display Modes
Old 08-02-2010, 11:45 AM  
Junior Member
Join Date: Aug 2010
Posts: 2
Default AC drain pipe question

I've resently cleaned the gunk out of my AC unit drain pipe and the unit is running just fine again. To get to the clog, I had to cut into the existing PVC pipe and repair it afterwards.

The original PVC drain pipe had a shallow trap (not like a U trap on the sink, but much more rounded) between the AC unit exhaust port and the clean out "T". I'm thinking of replacing the drain pipe with newer PVC and I'm wondering why there is a trap there at all. It seems that the flow would be much more efficient without any small dip and incline as it exits the AC unit. Can anyone tell me what purpose this trap serves? It seems to me that it's just another low spot for further gunk to build up and it makes using a snake even harder. Do I need this trap or can I just replace it with a straight section of PVC?

Thoughts and comments appreciated. Thanks!

sailtexas is offline  
Reply With Quote
Old 08-02-2010, 02:44 PM  
Established Member
Join Date: Nov 2007
Location: Grand Blanc, MI
Posts: 2,662
Liked 224 Times on 190 Posts
Likes Given: 102


Depending on how long the horizontal pipe run is until it reaches the vertical fall of the pipe, you might need it to prevent condensate from being sucked back into the system via the airflow of the blower motor.
Mine comes straight out the unit and immediately 90's into the vertical drain so there's no chance of it being sucked back in.
kok328 is offline  
Reply With Quote
Old 08-03-2010, 02:45 PM  
Junior Member
Join Date: Aug 2010
Posts: 2

Thank you for the insight. There is a 6" run coming out of the unit to a horizontal 90 degree elbow and then about a 2.5' run to the 90 degree elbow on the top of the vertical drop. I guess if I can find a similar PVC trap then I might as well replace it. If not, then I will just use the straight pipe. Thanks again.
sailtexas is offline  
Reply With Quote

A/C drain line, drain trap

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Similar Threads
Thread Thread Starter DIY Home Repair Forum Replies Last Post
PLEASE HELP! AC drain pipe caused flood slpstang02 HVAC 4 09-08-2009 04:56 PM
Can't clear galvanized pipe drain. Replace? DaringDamsel Plumbing Forum 6 07-08-2009 09:01 AM
Toilet drain pipe slope. npelzer Plumbing Forum 6 12-14-2007 11:34 PM
Risk of Explosion When Soldering Drain Pipe? travelover Plumbing Forum 3 10-22-2007 04:39 PM
Depth of drain pipe under slab Mudball Plumbing Forum 4 06-10-2006 07:34 PM

Newest Threads