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P-Trap design -is this right. ..

Posted by Totsie (My Page) on
Sun, Sep 30, 12 at 6:40

New system installed-looking at the PVC pipe coming out of the unit it's straight then dips kinda u shape-but a straight piece is sticking straight up right before it makes the u dip...I watch some videos on utube that looks like mine and it looks like that is where u could use as a clean out to flush I guess if you had a clogged drain.. But it had PVC cap on top, you had to remove.. Here's my question my has NO cap and wher the system kicked on lots of air is blowing out the pipe into the attic..seems not right to me.. Hope I have explained enough to get some thoughts if this is correct ..I will try to take a picture later and post-if I can...thanks for helping


Follow-Up Postings:

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RE: P-Trap design -is this right. ..

Picture of the setup ...lots of air coming out of the pipe ???


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RE: P-Trap design -is this right. ..

This looks not very stable setup but that's why I'm here to get some help


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RE: P-Trap design -is this right. ..

It is not a sanitary drain just a condensate drain.

Why did someone use an actual sanitary trap? Ad a metal one at that.

Get the installer back for the correct plastic trap and a cap.

Make sure the cap is only pressed on.

Do NOT glue it.


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RE: P-Trap design -is this right. ..

Not sure where u are commenting about metal and the sanitary trap ...and you are saying that no air conditionerd air is suppose to be coming out of the top mounted piece of PVC ??? This should be capped ? What is the use or need for this "vent piece anyway-thanks for helping me understand - however do you think this is a "honest mistake or shows lack of knowledge from a " qualified installer..


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RE: P-Trap design -is this right. ..

I think that's actually just insulation on the p-trap to prevent sweating. Not a bad idea, although they went overboard with the foil tape. Not a very neat install. I agree -- have them put on a 3/4" PVC cap (not glued).


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RE: P-Trap design -is this right. ..

Ok this is supposed to be capped? With no cold air blowing into attic correct? What is the purpose or use for this to be there ? Does this show lack of knowledge of the installer ??? 0n my other system I see the same PVC vent pipe but it is installed after the ptrap with no air coming from it... So is suppose to be before or after the ptrap drop piece... Found the direction said it should be a 3inch dip...sorry if not understanding I am only a paying customer to this installer....ps haven't paid yet. Lots of issue with this crew..read my other (rant) about their lack of basic knowledge for the copper tubing-under my totsie name...so I want to address all possible issues before settling my account ...so please point out any helpful tips I may want to look at-as stated earlier post my Infinity thermostat Not programmed correctly and that was installed by their most qualified tech (set up as one stage ac-my is suppose to be2 stage)...heater not operational because needs new flue pipe they will be back this week but Really worried about quality of their work..thanks for helping !!!


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RE: P-Trap design -is this right. ..

"Ok this is supposed to be capped? With no cold air blowing into attic correct?"

The entire purpose of the trap in the condensate line is to prevent air from exiting.

Cap the clean out access.

The air pressure is so low it just needs a solid push to wedge it on.


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RE: P-Trap design -is this right. ..

The vent should be after the trap not in front of it. If you cap it you no longer have a vent. If you have air coming out of the PVC pipe, then a P trap may not be required. Below is a link I found.

It there a trap under the foil? The picture looks like a 90 degree elbow. Where do the condensate lines drain? Do you have an overflow switch on the primary or secondary pan?

What is holding up the gas line? It seems to be suspended by the flex line. Does the PVC for the secondary pan have a proper pitch? It appears to be parallel to the floor.

Here is a link that might be useful: Proper Installation of AC condensate vent


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RE: P-Trap design -is this right. ..

I think the link above is showing an air handler, in which case the blower is AFTER the coil, subjecting the drain line to a negative pressure. In this case, yes, the vent should be AFTER the trap, not before. If it were before the trap it would render the trap useless (if not capped). In the OP's case, however, the coil is after the blower and the drain is under a positive pressure. Technically a trap isn't really needed, although they aren't uncommon to see in all installations. Having one should in theory help prevent conditioned air from blowing out the drain line, if it's deep enough. I personally don't see a benefit to having a vent after the p-trap in this case. I think it's fine where it is, but it should be capped, and it's purpose would be for cleaning the trap periodically.


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RE: P-Trap design -is this right. ..

I recommend installing an EZ trap. The trap is a clear tube. This allows you to visually check if there is any blockage. It comes with three caps and a cleaning brush.

You should also insist on a overflow cut off swith be installed on the coil.

Here is a link that might be useful: EZ Trap Condensate trap


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RE: P-Trap design -is this right. ..

I just had my new furnace and ac installed. The furnace is int he basement. Mine has the trap just like the one lined to above. I thought it was nice that it came with a little brush to clean it out once in a while, and that it is clear so you can see what is building up inside of it. My old one just had a pvc pipe, no special cleanout, luckily I never had a clog or anything. Note the cap on the vent. The little clear tube going up in the last picture is the condensate line coming up out of the condensate pump. I never had that before either. My old one had 2-3 feet of skinny pvc pipe going from the furnace to the french drain. We stepped on it and broke it in the first year. Really dumb install that was!

Can only get one pic to post at a time. See pics in next 2 posts if you are interested


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RE: P-Trap design -is this right. ..

another view of ez trap


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RE: P-Trap design -is this right. ..

last pic of ez-trap and condensate line


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RE: P-Trap design -is this right. ..

Nice pictures. In time the water in the clear tube will turn brown. This is normal and is fine as long as there is no obstruction.

The device right above the trap is also made by EZ Trap. It is the overflow kill switch. It will shut down the furnace in the event the condensate pan in the coil overflows.


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