Results 1 to 48 of 48
  1. #1
    Stephen Houmard's Avatar
    Stephen Houmard Guest

    Default HVAC condensation drain line vent cap

    Help!
    I ran across a furnace with a AC unit. The condensation is draining out of the over flow line into the pan. The over flow is higher than the main drain. Is this happing because the main drains vent cap is closed? It should be open...correct? The fan is blowing the condensation out of the path of least restiance.

    When I remove the cap the unit drains properly.
    Should I have left the cap off?

    Similar Threads:
    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Certified Master Inspector CMI

  2. #2
    Join Date
    Feb 2008
    Location
    Chicago IL
    Posts
    1,940

    Default Re: HVAC condensation drain line vent cap

    Water will always take the path of least resistance. With the cap on the primary drain, the overflow may have less resistance. I doubt that is the whole story though. If it's draining out the overflow the primary may be partially clogged. This happens commonly over time. A gunky, slimy build-up forms at the outlet. I know a lot of HVAC run a fish or coat hanger through the opening when they do annuals.
    As far as leaving the cap off... if it was there when you showed up it should be there when you leave. If you change existing conditions (which isn't our job) then you could be in for trouble. Note it in the report with a (recommendation).

    www.aic-chicago.com
    773/844-4AIC
    "The Code is not a ceiling to reach but a floor to work up from"

  3. #3
    Join Date
    Mar 2007
    Location
    Dallas, Texas
    Posts
    4,112

    Default Re: HVAC condensation drain line vent cap

    It is plumbed incorrectly.
    The primary drain should be trapped and have a open vent higher than the top of the drain pan located DOWN STREAM of the trap.
    The secondary should also be trapped before dumping into the pan. Most manufacturers will specify a certain depth trap, 3 inch is common.
    Air flow through the drain ports will cause the water to be pushed in or out.
    The problem is NOT the cap, it is the lack of a trap on both drains.

    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  4. #4
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Jim,

    Looks like that is a 'clean out cap' on the inlet side of the primary condensation line trap (looks like a curved trap going down from that tee fitting), thus, that part could be plumbed correctly ... "could be" ...

    However, yes, the secondary condensation line also requires a trap, and it can then drain into the drain pan.

    Stephen,

    When water is coming out the secondary condensation line, that is an indication of a problem with the primary condensation line. That problem could be one of many things, from being clogged, partially clogged, improperly trapped, not properly sloped, etc.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  5. #5
    Larry Brooks's Avatar
    Larry Brooks Guest

    Default Re: HVAC condensation drain line vent cap

    Why would you put a trap on the secondary overflow. If the primary drain is working there will be no water in the secondary drain trap, allowing outside air to be pulled back into the system. Usually the secondary drain is plugged and if there is a blockage in the primary drain the water will overflow into the pan. I know the trap looks good on the secondary, but would do little good if the primary drain is working.


  6. #6
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Larry Brooks View Post
    Why would you put a trap on the secondary overflow.
    For the same reason there is a trap on the primary condensate line - to keep air from being sucked in ... or blown out ... of the unit.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  7. #7
    Join Date
    Feb 2008
    Location
    Chicago IL
    Posts
    1,940

    Default Re: HVAC condensation drain line vent cap

    You guys are making assumptions in this case that the picture does not support.
    - putting a trap on the before it enters the pan is non-sense. No HVAC does that, there isn't even room to do it without some really creative work. It is a waste of time and effort.
    - You can't tell from the picture if there is a trap on the primary or not, so don't assume.

    www.aic-chicago.com
    773/844-4AIC
    "The Code is not a ceiling to reach but a floor to work up from"

  8. #8
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Markus Keller View Post
    You guys are making assumptions in this case that the picture does not support.
    Nope. The photo supports what I stated.

    - putting a trap on the before it enters the pan is non-sense. No HVAC does that,
    EVERY code out there does - they state to install in accordance to the manufacturer's installation instructions, and they state to install a trap there.

    there isn't even room to do it without some really creative work. It is a waste of time and effort.
    There is plenty of room there, no need to get all excited about it. It is also well worth the effort.

    - You can't tell from the picture if there is a trap on the primary or not, so don't assume.
    Which is why I stated, if you read my post: "(looks like a curved trap going down from that tee fitting)".

    You need to read all of each post before making broad, and incorrect, statements such as those, then you also need to read the manufacturer's installation instructions regarding traps.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  9. #9
    Join Date
    Feb 2008
    Location
    Chicago IL
    Posts
    1,940

    Default Re: HVAC condensation drain line vent cap

    So you are claiming to read the manuf. instructions for a unit that you can't see the name/brand of? Wow, that is incredible.
    Yes, the drain should be trapped but with my mere mortal eyes I can't see that the primary isn't.
    The idea that the unit won't/isn't functioning properly because the trap isn't within the drain pan is crap.
    Please prove me wrong.

    www.aic-chicago.com
    773/844-4AIC
    "The Code is not a ceiling to reach but a floor to work up from"

  10. #10
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Markus,

    You need to learn to read posts better.

    I've never seen an air handler unit installation instruction which had a secondary condensate drain opening which did not state that it was to be trapped.

    Why don't you start reading all the ones you can find as you inspect, and those in the internet. Every time you find one with a secondary condensate opening which say you do not need to trap it, and when it does not end in a shut off switch (which effectively traps it as it is dead ended), post it here. I'm all eyes and ears trying to learn new stuff - you see stuff I've never seen, post it here so we can all learn.

    Until then, though, all those secondary condensate openings need to be trapped.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  11. #11
    J Lawrence's Avatar
    J Lawrence Guest

    Default Re: HVAC condensation drain line vent cap

    I just read the instructions on my recently installed inside coil for my cooling system.

    The instructions state a 3" deep trap be installed on the coil. My installer told me that a trap was not required because it was a 'blow through' as opposed to a draw through like most heat pump applications are. He also said that a trap on the coil drain would be much more likely to clog/plug up with garbage over the season.

    There is currently no clean out on the drain line either. The line goes into a pump at the base of the furnace, but that won't be that way for long, as I can (as opposed to the installer) set it up as a gravity drain. To circumvent the next question, the pump is there to pump out the condensate from the 94% efficient furnace into an condensate neutralizer, then outside. There will not be a clean out on the drain line.

    I'm a fairly regular reader of this board, not much of a poster. I'm going back to lurk mode.

    J


  12. #12
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by J Lawrence View Post
    I just read the instructions on my recently installed inside coil for my cooling system.

    The instructions state a 3" deep trap be installed on the coil. My installer told me that a trap was not required because it was a 'blow through' as opposed to a draw through like most heat pump applications are. He also said that a trap on the coil drain would be much more likely to clog/plug up with garbage over the season.
    Are you going to believe your installer or the manufacturer who made the unit?

    I'd go with the manufacturer myself.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  13. #13
    Join Date
    Mar 2007
    Location
    Dallas, Texas
    Posts
    4,112

    Default Re: HVAC condensation drain line vent cap

    These are some diagrams that I stole from other posts, one of which was from Lennox. These are pretty representative of what is out there from the manufacturers.
    One thing I also recommend to keep the secondary trap seal from evaporating is to prime it with mineral oil.
    The only purpose of traps is to keep the air from blowing through the trap and wasting energy. The vent has to be on the down stream side of the trap to make the drain line drain properly without sucking the trap dry.
    This is basic stuff to any plumber, but unfortunately A/C techs in this area are not plumbers and do not seem to understand the physics or the manufacturer's instructions.

    I did make an assumption of incorrect primary drain design since I could not see the entire line, my apologies. I could not SEE a correct trap and vent on the primary and the secondary is WRONG.

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  14. #14
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Jim Luttrall View Post
    I could not SEE a correct trap and vent on the primary
    Jim,

    I think that is a service access point for blowing the line out as there is a cap on it (at least it looks like there is a cap on it).

    Here are some drawings from Rheem / Ruud installation instruction manuals regarding traps.

    The first shows the typical dimensions for the trap.

    The second shows that a running trap is not allowed.

    The third shows that not only is a trap required for the primary, but for the secondary as well.

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  15. #15
    Join Date
    Feb 2008
    Location
    Chicago IL
    Posts
    1,940

    Default Re: HVAC condensation drain line vent cap

    Hmm, interesting, I said there isn't enough room to install a trap within the drain pan area and attempting to do so is non-sense. JP said I was wrong and that 'it's well worth the effort' to try.
    I'd like to see you install the trap from the photo inside the pan. That would be magic.

    www.aic-chicago.com
    773/844-4AIC
    "The Code is not a ceiling to reach but a floor to work up from"

  16. #16
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Markus Keller View Post
    I'd like to see you install the trap from the photo inside the pan. That would be magic.
    Markus,

    You've got to stop thinking within the confines of that box you have there.

    Raise the a/c 2" or more above where it sets in relation to that pan, install a standard trap.

    There is nothing which requires the a/c air handler unit to be setting at the height of the lip of the pan - I mean, that's so simple to do ...

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  17. #17
    Aaron Miller's Avatar
    Aaron Miller Guest

    Default Re: HVAC condensation drain line vent cap

    That would be magic.
    Markus:

    Peck is dead on here. That is not magic, it's called sheet metal. It can be made in any size one desires. Even big enough to go under the traps that are required.

    Aaron


  18. #18
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Aaron Miller View Post
    That is not magic, it's called sheet metal.

    Aaron,

    I was thinking of something called "air" , ...

    ... as in 'provide more "air" space between the bottom of the AHU and the pan by raising the AHU or lowering the pan' (depending on which is easiest to do).

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  19. #19
    Aaron Miller's Avatar
    Aaron Miller Guest

    Default Re: HVAC condensation drain line vent cap

    ECJ:

    But, that would require actual forethought on the part of the builder and his band of HVAC thugs. They would have to find a place in the attic where they could gain the extra space. That would kill more brain cells, causing even fewer synapses . . . what's a mother to do?

    Aaron


  20. #20
    Rod Aparicio's Avatar
    Rod Aparicio Guest

    Default Re: HVAC condensation drain line vent cap

    I just scrolled all the way down to reply to this post so if someone already mentioned it,oops!

    Stephen, is that a loose NM electrical cable in foreground? What was it feeding and how did you address it?

    Thanks.


  21. #21
    J Lawrence's Avatar
    J Lawrence Guest

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Jerry Peck View Post
    Are you going to believe your installer or the manufacturer who made the unit?

    I'd go with the manufacturer myself.
    Fine.

    A lot of things work well in the factory test area, but not in the field.

    I happen to agree with the installer.


  22. #22
    Anthony Alderman's Avatar
    Anthony Alderman Guest

    Default Re: HVAC condensation drain line vent cap

    "A lot of things work well in the factory test area, but not in the field.
    I happen to agree with the installer."


    As an inspector you really don't have that option.

    Tony


  23. #23
    J Lawrence's Avatar
    J Lawrence Guest

    Default Re: HVAC condensation drain line vent cap

    I never said I was a home inspector


  24. #24
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by J Lawrence View Post
    A lot of things work well in the factory test area, but not in the field.

    I happen to agree with the installer.
    Quote Originally Posted by Anthony Alderman View Post
    As an inspector you really don't have that option.
    Quote Originally Posted by J Lawrence View Post
    I never said I was a home inspector
    Does not matter if you are, or are not, a "home inspector" or even if you are a "code inspector".

    Unless you are *THE MANUFACTURER* and are willing to provide an engineering letter for the change, *the code* requires it to be installed *in accordance with the installation instructions*.

    Technically, not doing so means it was not installed in accordance with the installation instructions, which then becomes a "code violation", whether you like it or not, or whether you prefer it a different way or not.

    Something like that condensate drain line will not (in my opinion) be cause for declaring it 'not in conformance with its listing and labeling to the extent that it would then need field re-certification', but there are some changes which would go that far.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  25. #25
    Aaron Miller's Avatar
    Aaron Miller Guest

    Default Re: HVAC condensation drain line vent cap

    Maybe this will make Peck happy. Of course we could have used .80 CCA pressure-treate wood and stainless steel cables, but hey . . . .

    Last edited by Aaron Miller; 05-17-2008 at 12:14 PM.

  26. #26
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Aaron Miller View Post
    Maybe this will make Peck happy.

    Nope.

    No trap on that secondary condensate line. Plenty of room for one, just did not bother with it.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  27. #27
    Aaron Miller's Avatar
    Aaron Miller Guest

    Default Re: HVAC condensation drain line vent cap

    Nope.
    Picky MF, aren't you?

    Aaron


  28. #28
    Aaron Miller's Avatar
    Aaron Miller Guest

    Default Re: HVAC condensation drain line vent cap

    ECJ, et al. :

    It just occurred to me that folks may be taking my shorthand to heart in a way that I had never intended. Let's take the last post in this thread for example, shall we?

    MF. Now there are some course characters among you who may think I meant something vulgar or obscene by that. It actually was not a reference to maternal reproductive activities. I am far above such things.

    MF was only intended to connote "minutiae finagler". Now see, that was not so bad was it? And, it is accurate beyond imagination in this particular case.

    I suppose I should explain other terms I have used like SOB. This is another term not intended to address one's matron, but merely means "stratospherically obtuse bubba". Whenever I have aimed and shot that one, it was sorely earned by its recipient. Shots like that need not even be pointed in the target's general direction. They are so attracted that they find their own way without any assistance. Isn't that just wonderful how that works?

    Now other terms are a bit more delicate to diffuse, like phuque, and its many variants. It is actually correctly written: phuqué , but the Hann's simplistic word processor has made the addition of the little eyebrow thingy above the final e impossible to attain without much consternation. So, I usually leave it out. Now that it is there you can probably recognize it as a jazz term. For those of you interested in the genre try www.phatfuque.com . See that eyebrow went away again because the search engines are inbred relatives of the Hann's word processor. Not too bright these guys . . .

    Though the term has its roots in jazz, it has been high-jacked by the common man on the street and has several rather loosely regulated multi-purpose meanings. Because I cannot be everywhere and know everything at all times, like Peck, I simply cannot know how this one will be perceived by any particular person at any given time. But, it is such a grand word, that I dare not eschew its use on the off chance that someone will misunderstand me.

    I am so glad we had this little chat to clear things up a bit. I certainly think it is important to be clearly understood by ones peers - and those who don't quite make that grade.

    Tata!

    Aaron


  29. #29
    Richard Rushing's Avatar
    Richard Rushing Guest

    Default Re: HVAC condensation drain line vent cap

    The easiest thing in the world (to do) would be to install the pan too close and "then" state that it can't be plumbed right-- a typical contractor who was "taught" this way and continues to perform the same type of work taught 20-30 years back.

    We simply know-better today to do things "as designed" vs "the way we were taught" (new vs old).

    Trying to justify a bad install by an even worse install is just wrong in any endeavour. This is exactly why we see so many drain lines installed wrong-- the installers just can't figure out how they were to suppose to do it right to begin with, then when someone (like an inspector) finds and points out the issue, they then justify their actions with something else (usually that they did wrong) to the client/ homeowner/ buyers/ agents.

    This kind of thinking sure does slow down the progression of advancing the HVAC industry, the building construction service professionals and the means of which the younger professionals (just starting out) are to learn from the older and more experienced contractors. I sure hope this way of thinking is not being passed along to the apprentices working under you.

    This is not a personal attack and shouldn't be taken as such, but more-so an observation as how the 'old' way of thinking should be re-considered for cutting down on how much time and energy you will have to put into explaining how/ why things were done a certain way when it clearly is contrary to "best practices" as well as manufacturers engineered recommendations.

    Richard


  30. #30
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Aaron Miller View Post
    ECJ, et al. :

    It just occurred to me that folks may be taking my shorthand to heart in a way that I had never intended. Let's take the last post in this thread for example, shall we?

    MF. Now there are some course characters among you who may think I meant something vulgar or obscene by that. It actually was not a reference to maternal reproductive activities. I am far above such things.

    Aaron,

    Glad to know that ...

    Being the small town simple boy I am, when I saw "MF" I thought something else ...

    But then ...

    ... I'm a John Deere man, not a MF.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  31. #31
    Aaron Miller's Avatar
    Aaron Miller Guest

    Default Re: HVAC condensation drain line vent cap

    ... I'm a John Deere man, not a MF.
    ECJ:

    Farmall here . . .

    Aaron


  32. #32
    Join Date
    Mar 2008
    Location
    Charlotte NC
    Posts
    2,297

    Default Re: HVAC condensation drain line vent cap

    I have not gathered actual numbers but I'm fairly sure that only 2 - 3% of the secondary drains I have inspected have a trap installed. Most of the secondary drains I see are plugged, and the only ones used as a secondary are in old installations or vertical flow units that do not have a secondary drain pan installed. The clean-out makes sense as a maintenance item and if you are going to install a trap it makes sense to cap the clean-out, otherwise it is defeated. The vent down stream of the trap makes sense to plumbers, as a means of breaking the vacuum, created by the many gallons per minute of condensate that gush through the 3/4" line.

    My bigger concern with condensate traps is that they are over a secondary drain pan or are wrapped with insulation if it is above a conditioned space. The trap (if there is one) in the picture would appear to be in an attic, and not insulated or above the auxiliary drain pan. When the cold condensate fills the trap, the trap sweats and now you have a nice spot in the ceiling below the unit.


  33. #33
    Douglas Gross's Avatar
    Douglas Gross Guest

    Default Re: HVAC condensation drain line vent cap

    I'm curious - why would you bother to put a trap on the primary drain but not the secondary drain (assuming it is connected)?
    Wouldn't the system blow or suck air via the secondary drain, even as the primary drain is nicely protected with its trap?


  34. #34
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Douglas Gross View Post
    I'm curious - why would you bother to put a trap on the primary drain but not the secondary drain (assuming it is connected)?
    Excellent question.

    Wouldn't the system blow or suck air via the secondary drain, even as the primary drain is nicely protected with its trap?
    YEP!

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  35. #35
    Douglas Gross's Avatar
    Douglas Gross Guest

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Jerry Peck View Post
    Excellent question.

    YEP!
    Thanks for the reply!
    I just checked the installation guide for my unit, and it actually states that the auxilliary drain should not be trapped. It does give details on how the primary drain trap should be set up.
    Can you think of a reason for this? It doesn't make sense to me.


  36. #36
    Aaron Miller's Avatar
    Aaron Miller Guest

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Douglas Gross View Post
    Thanks for the reply!
    I just checked the installation guide for my unit, and it actually states that the auxilliary drain should not be trapped. It does give details on how the primary drain trap should be set up.
    Can you think of a reason for this? It doesn't make sense to me.
    Douglas:

    The attorneys who wrote the instructions were not communicating with the engineers who designed it who were not communicating with the technicians who installed it who were only interested in doing it fast and not right.

    Aaron


  37. #37
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Douglas Gross View Post
    I just checked the installation guide for my unit, and it actually states that the auxilliary drain should not be trapped.
    "it actually states that the auxilliary drain should not be trapped"

    Typically, there is a primary condensate drain (which gets trapped), a secondary condensate drain (which gets trapped) and an auxiliary pan with an auxiliary condensate drain (which does not get trapped).

    Are you sure they are referring to the 'secondary condensate drain' with that wording, or to the 'auxiliary condensate pan drain'?

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  38. #38
    Douglas Gross's Avatar
    Douglas Gross Guest

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Jerry Peck View Post
    "it actually states that the auxilliary drain should not be trapped"

    Typically, there is a primary condensate drain (which gets trapped), a secondary condensate drain (which gets trapped) and an auxiliary pan with an auxiliary condensate drain (which does not get trapped).

    Are you sure they are referring to the 'secondary condensate drain' with that wording, or to the 'auxiliary condensate pan drain'?
    Hmmm, I'm not sure. I can look when I get home.
    It is a convertible unit that is setup for downflow with electric heating coils. The condensate drain outlets are a cluster of three - I assume this ensures that one will be higher if it is setup for horizontal flow.


  39. #39
    Join Date
    Mar 2007
    Location
    Dallas, Texas
    Posts
    4,112

    Default Re: HVAC condensation drain line vent cap

    I just checked the installation guide for my unit, and it actually states that the auxiliary drain should not be trapped.
    Like Jerry said, "auxiliary" drain is not a secondary drain which is integral to the unit, it would be the auxiliary pan drain under the unit which would have no reason to be trapped since it would be open to the atmosphere on both ends of the pipe.

    Of possibly if they really did mean the secondary drain on the unit, then Aaron's theory would kick in.

    Bottom line, if you have air flow in or out of the indoor coil drain pipes, it is wrong.

    The only way to prevent air flow through a functional drain is with a trap which continually contains water.

    It is not rocket science, but it may as well be since most A/C techs just don't get it.

    I can tell you while I was in two different schools, plumbing traps and vents were not covered.

    This is really the realm of a plumber, but the A/C guy is the one who does the condensate drain connections on residential.

    I still have not found ONE attic unit that was done 100% right. Some have come close, but most don't even attempt to trap the secondary and most can't even get the primary trap right.

    50% or more will vent upstream of the trap which lets the air flow unimpeded through the vent from the unit and lets the trap be sucked dry or just keeps the drain line from draining properly. (Think of a drinking straw with your thumb over the end)

    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  40. #40
    Join Date
    Mar 2007
    Location
    Dallas, Texas
    Posts
    4,112

    Default Re: HVAC condensation drain line vent cap

    From Saturdays inspection Carrier instructions. Underline is mine.
    Units are equipped with primary and secondary 3/4--in. FPT drain
    connections. For proper condensate line installations see Fig. 1, 2,
    3, 5 and 6. To prevent property damage and achieve optimum
    drainage performance, BOTH primary and secondary drain lines
    should be installed and include properly--sized condensate traps.
    (See Fig. 19 and 20.) Factory--approved condensate traps are
    available. It is recommended that PVC fittings be used on the
    plastic condensate pan. Finger--tighten plus 1--1/2 turns. Do not
    over--tighten. Use pipe dope.
    NOTE
    : When connecting condensate drain lines, avoid blocking
    filter access panel, thus preventing filter removal. After connection,
    prime both primary and secondary condensate traps.
    NOTE
    : If unit is located in or above a living space where damage
    may result from condensate overflow, a field--supplied, external
    condensate pan should be installed underneath the entire unit, and a
    secondary condensate line (with appropriate trap) should be run
    from the unit into the pan. Any condensate in this external
    condensate pan should be drained to a noticeable place. As an
    alternative to using an external condensate pan, some localities
    may allow the use of a separate 3/4” (19 mm) condensate line (with
    appropriate trap) to a place where the condensate will be
    noticeable. The owner of the structure must be informed that when
    condensate flows from the secondary drain or external condensate
    pan, the unit requires servicing or water damage will occur.
    Install traps in the condensate lines as close to the coil as possible.
    (See Fig. 20.) Make sure that the outlet of each trap is below its
    connection to the condensate pan to prevent condensate from
    overflowing the drain pan. Prime all traps, test for leaks, and
    insulate traps if located above a living area. Condensate drain lines
    should be pitched downward at a minimum slope of 1” (25 mm)
    for every 10’ (3 m) of length. Consult local codes for additional
    restrictions or precautions.


    How many inspectors inform the home owners to watch the secondary drain termination and call for service?
    How many insulated condensate drain lines/traps do you see?
    Some of this information is brand specific to Carrier, but it is good practice on everything.
    Jim

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  41. #41
    Larry Brooks's Avatar
    Larry Brooks Guest

    Default Re: HVAC condensation drain line vent cap

    What keeps the secondary trap primed. The secondary drain is about 1/2 inch above the primary drain.


  42. #42
    John Allingham's Avatar
    John Allingham Guest

    Question Re: HVAC condensation drain line vent cap

    What the heck are you guys talking about. I feel like I must be living on another planet. I've never seen a trap in the A/C drain line and I've never seen a secondary drain. Is it because our HVAC equipment is always in the basement?

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images

  43. #43
    Join Date
    Mar 2007
    Location
    Dallas, Texas
    Posts
    4,112

    Default Re: HVAC condensation drain line vent cap

    What keeps the secondary trap primed. The secondary drain is about 1/2 inch above the primary drain.
    Absolutely nothin'
    That is why I recommend priming the trap with mineral oil when it is installed. That's just me though, nothing in the manuals will tell you that.
    Mineral oil is non-toxic, lighter than water, and won't evaporate (at least not quickly)

    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  44. #44
    Join Date
    Mar 2007
    Location
    Dallas, Texas
    Posts
    4,112

    Default Re: HVAC condensation drain line vent cap

    I've never seen a trap in the A/C drain line and I've never seen a secondary drain. Is it because our HAVOC equipment is always in the basement?
    Do these drain lines terminate inside the conditioned space? In the same room as the equipment?
    Not as big a deal, but I have NEVER dealt with an A/C unit in a basement.
    This is the land of slabs!

    Last edited by Jim Luttrall; 05-06-2008 at 05:23 AM.
    Jim Luttrall
    www.MrInspector.net
    Dallas, Texas

  45. #45
    Aaron Miller's Avatar
    Aaron Miller Guest

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Jim Luttrall View Post
    Do your these drain lines terminate inside the conditioned space? In the same room as the equipment?
    Not as big a deal, but I have NEVER dealt with an A/C unit in a basement.
    This is the land of slabs!
    ACs in basements in North Texas must be UL-rated for operation under 8' of water. Subconditioners.

    Aaron


  46. #46
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    25,318

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by John Allingham View Post
    I've never seen a trap in the A/C drain line and I've never seen a secondary drain. Is it because our HVAC equipment is always in the basement?
    John,

    Being installed in a basement has *nothing to do with* being required to have traps. Air still blows out / gets sucked in through those drain line(s). Also, that red plug is the secondary condensate opening, and it is required by both the code and the manufacturer's installation instructions to have a primary condensate drain and a secondary condensate drain and both are required to be trapped (except for when a cut off switch is installed in the secondary condensate drain line and effectively dead ends the line - but I think those installations are foolish installations anyway, 'allowed' but will still flood and overflow).

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  47. #47
    John Allingham's Avatar
    John Allingham Guest

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Jerry Peck View Post
    John,

    Being installed in a basement has *nothing to do with* being required to have traps. Air still blows out / gets sucked in through those drain line(s). Also, that red plug is the secondary condensate opening, and it is required by both the code and the manufacturer's installation instructions to have a primary condensate drain and a secondary condensate drain and both are required to be trapped (except for when a cut off switch is installed in the secondary condensate drain line and effectively dead ends the line - but I think those installations are foolish installations anyway, 'allowed' but will still flood and overflow).
    Thanks Jerry. Like I said, I've inspected hundreds up here and not seeen one A/C drain trap and no secondary drain ever. I guess it is a waste of air.
    I've seen lots where the drain has become clogged. The tray overflows, drips down through the furnace, runs along the basement floor and down the floor drain, which is normally within a few feet.
    I guess they take the shortcuts because the consequences are relatively minor compared to an attic installation. Still doesn't make it right.


  48. #48
    John Allingham's Avatar
    John Allingham Guest

    Default Re: HVAC condensation drain line vent cap

    Quote Originally Posted by Jim Luttrall View Post
    Do these drain lines terminate inside the conditioned space? In the same room as the equipment?
    Not as big a deal, but I have NEVER dealt with an A/C unit in a basement.
    This is the land of slabs!
    In the case shown, the drain line is inserted into a basement drain trap primer connection. Other times they are inserted directly into the floor drain. Quite often they are combined with the HE furnace drain line.

    Never done a slab up here.


Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •