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Old 04-03-2012, 11:22 AM   #1
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Condensate Drain Line Mystery (pan full but no primary clog?)


Hi all,

The condensation from my central air handler has been running through the secondary drain line and into the secondary drain pan (below the unit) for quite some time. My husband and I initially thought that the primary line was clogged, but this does not seem to be the case.

Here are pictures of our unit:

and


We had an HVAC technician come out to perform basic maintenance (including flushing out the drain lines) a month ago. He's convinced that we've got mold and mildew growing in our coil box and drain lines (and growing so fast that it's re-clogging them even two weeks after his visit). Of course, he's also trying to sell us an expensive UV system.

Unfortunately, the primary line seems to connect to our house's plumbing (you can hear air through one of the bathroom sink drains when the AC is on), so I can't suction it out myself, but I don't think the primary line is clogged because you can feel strong airflow through the pour spout when you remove the cap. At most, there might be a layer of sludge/mildew along the bottom of the primary line right where it exits the evaporator coil box, but I don't know how likely that is.

I opened the coil box yesterday, and there was some mold/mildew along the material above the evap coils, but none on the upper/outside portion of the coils (we have an A-frame with a plate blocking view of the inside portion of the coils and fins). I sprayed liberally with fungicide (rated for HVAC system use) and closed the box.

There's no trap on the primary line, the pour spout hasn't always been capped, and air escapes from the coil box around the panel and the front seam in the duct work immediately above the coil box (I've sealed this with foil tape for now and will add sealant later).

Given that the primary line doesn't seem to be clogged, the most likely (and frustrating) explanation seems to be that the unit wasn't installed well. You'll notice that the primary and secondary drain lines connect to the coil box at the same height, so someone would have had to add just the right slope to the unit or primary drain pan to keep condensation flowing through the primary line. As it is, I suspect that water flows freely through both at the same time.

What's going on? I'm new at this, so I'd appreciate any help or insight. Thanks!

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Old 04-03-2012, 01:07 PM   #2
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Condensate Drain Line Mystery (pan full but no primary clog?)


That pan is an OVERFLOW pan.
It is not intended to have the condensate accumulate in it.

Buy a condensate pump.
Have these water sources lead to the pump and then have the pump push the water to a drain.

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Old 04-03-2012, 01:58 PM   #3
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Condensate Drain Line Mystery (pan full but no primary clog?)


I just noticed something. It appears you have a first and secondary drain line from the air handler. The first air handler drain line seems proper except it should have a trap.

The secondary drain line however shouldn't end nor be drained directly into the bottom drip pan. That pan is strictly for overflow and excessive condensation protection.

That secondary air handler drain line should be tied directly into the drain line at some point where it can't backflow into the drip pan. Otherwise, it needs to have it's own line leading directly outside. It will need a trap as well. See this diagram on proper draining for air handlers, page 7 in particular.

You may want to open the access door to the air handler and check for any clogs where the lines enter the air handler pan. Dirt/dust can clog those over time.

Good luck

Last edited by Ralph III; 04-03-2012 at 02:29 PM.
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Old 04-03-2012, 04:13 PM   #4
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Condensate Drain Line Mystery (pan full but no primary clog?)


http://www.ashireporter.org/articles...s.aspx?id=1648
Proper piping will solve a lot of problems.
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Old 04-03-2012, 05:28 PM   #5
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Condensate Drain Line Mystery (pan full but no primary clog?)


There are several issues here. I'm afraid I will be long winded but here goes. First of all, this is NOT an air handler, it is a cased cooling coil mounted on an older upflow low efficiency gas furnace. Ralph III's diagram is for another piece of equpment entirely and does not apply. In current practice it is not necessary to install traps in positive pressure lines, just negative pressure coils such as the diagram. Ignore it. Tarheel is correct, that is an overflow drain pan and should be dry under normal circumstances. As Rep just said, proper piping will solve a lot of problems. Actually a proper installation that is up to code will solve a lot of problems. This one is not. If you are getting air in a drain from the furnace the condensate has been directly coupled to the sewer without a trap. Not only not code, this is potentially dangerous because when the blower is off, you are getting sewer gas back in the house. The pipes need to be cut and remove the connections from the pan and look in. One hole will be completely open, the other will be blocked by at least half. Plug the partial hole with a 3/4" plastic pipe plug. Reinstall the other pipe connector and run a new line with the correct slope to a proper, vented drain connection. If you are not comfortable doing this, hire a NATE certified technician. Where does the drain for the overflow pan go? Why wasn't the line run to that drain? Why isn't the electric wire in a conduit? Where is the emergency shut off switch? Why weren't these issues caught and addressed before now? Clearly your installer nor your service technician are NATE or other agency certified technicians, these problems would have been cleared up a long time ago. Before you do any further repairs, stand back and take a good long look at the general condition of your furnace. Notice the rust and corrosion in the pan and know that the bottom of your furnace is in no better shape, probably worse. Then, consider the removal and replacement with a new high efficiency unit installed by a certified technician up to current building codes and installation practices. You and your family will be much safer and you will save a bunch of money in the long run.
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Old 04-03-2012, 05:34 PM   #6
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Condensate Drain Line Mystery (pan full but no primary clog?)


Holy Moly! I just re-read what I wrote. If you are getting air from the furnace back in a sink drain you either have a problem with the sink drain trap or there isn't one to begin with! You need to address this right
now. You need to trap your plumbing or you have a blocked sewer vent. This is extremely serious. I think you need more than an HVAC technician, you need a plumber sooner not later.
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Old 04-03-2012, 07:36 PM   #7
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Condensate Drain Line Mystery (pan full but no primary clog?)


Welcome aboard GarryE. I like your style already.
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Old 04-03-2012, 09:33 PM   #8
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Condensate Drain Line Mystery (pan full but no primary clog?)


Quote:
Originally Posted by GarryE View Post
Holy Moly! I just re-read what I wrote. If you are getting air from the furnace back in a sink drain you either have a problem with the sink drain trap or there isn't one to begin with! You need to address this right
now. You need to trap your plumbing or you have a blocked sewer vent. This is extremely serious. I think you need more than an HVAC technician, you need a plumber sooner not later.
Hello Garry and welcome.

If you re-read my post the point was she appears to have no trap. I pointed to a quick reference for her that is indeed applicable, pg 7, "Typical Condensate Drain Connection". It's essentially identical to the Trane illustration as REP linked to and as you agreed to? They in fact make the same statements but do offer various methods and more details. I have no idea what type system the OP has and wasn't the point. Irrespective, they need to do it in the manner the manufactures suggests.

My error would be in stating the secondary drain should have a trap as well and should not end in the pan, as a matter of fact. There are various ways of handling those as pointed out in link REP noted, otherise this HVAC forum is relevant to the subject. In continuing, negative systems require a trap, whereas positive is optional though prefered by many for various reasons as some hvac pros note, see HERE . Again, it all depends on requirements and/or as some pros may prefer.

It wouldn't be my preference to end the secondary drain in the pan because if the primary line became clogged or partially clogged (unbenounced) then you can end up with standing water in the drip (overflow) pan at times. That can lead to a rusted out pan over time and possible sheetrock damage, etc. I know, because it happened to us.

I would connect that secondary drain line downline somewhere to the drip pan drain line. The secondary drain line is supposed to be routed in such a manner as the homeowner will notice water draining from it, because that is an indication of an issue. However, if you read those HVAC threads as pointed out by some HVAC pros there, things are often not understood or done as they should be. If they have those lines tied into their sewer lines, then they better have a trap on every line, especially if dealing with a gas unit...

Take care, Ralph

Last edited by Ralph III; 04-03-2012 at 10:10 PM.
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Old 04-04-2012, 08:40 AM   #9
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Condensate Drain Line Mystery (pan full but no primary clog?)


Hi everyone, and thanks for the input.

I do recognize that we're not supposed to have standing water in the pan--I bought a shop vac to take care of this problem and hacked a quick fix with a funnel and rubber tubing to get the drainage from the secondary line to bypass the pan altogether. This isn't perfect, but it should at least take care of the problem of the pan holding water and rusting out.

Just to clarify the issue with airflow in the bathroom sink, you can't feel air coming out of the sink drain, you only hear it moving through the pipes below, and there is a trap immediately beneath the sink in question. I recognize that the primary condensate drain line should still be trapped, but does this alleviate some of your concerns?

As for the problem of water constantly draining through the secondary line, my husband mentioned yesterday that water has been draining that way since he bought the house (new) a few years ago, which suggests that this problem really does come from a terrible installation job. It all seems obvious now, but as first-time homeowners (and people who didn't grow up in super-handy households), it wasn't obvious at the time. At least the overflow pan didn't rust through before we realized the extent of the problem.

Thanks again for your feedback!
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Old 04-04-2012, 09:26 AM   #10
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Condensate Drain Line Mystery (pan full but no primary clog?)


Quote:
CarrieLP; "Hi everyone, and thanks for the input.

...hacked a quick fix with a funnel and rubber tubing to get the drainage from the secondary line to bypass the pan altogether. This isn't perfect, but it should at least take care of the problem of the pan holding water and rusting out."
That's the right idea but you need to get some pvc and make it a permanent fix. You could just loop over the drain pan lip with a trap and then tie it into the overflow pans drain line at some point where it cannot flow back into the pan. Do not tie it into the primary condensate line.


Quote:
CarrieLP; "Just to clarify the issue with airflow in the bathroom sink, you can't feel air coming out of the sink drain, you only hear it moving through the pipes below, and there is a trap immediately beneath the sink in question. I recognize that the primary condensate drain line should still be trapped, but does this alleviate some of your concerns?"
You need to have a trap on that primary air handler drain line and as near to the unit as possible. This is especially vital if the condensate line is tied into the houses sewer lines, which is against code in many localities as I understand. It's better to run those condensate lines directly outside.


Quote:
CarrieLP; "As for the problem of water constantly draining through the secondary line, my husband mentioned yesterday that water has been draining that way since he bought the house (new) a few years ago, which suggests that this problem really does come from a terrible installation job..."
We had a similar problem but no secondary condensate line to notify us of the issue. It wasn't until our pan rusted out and stained some sheetrock before I was aware. Your issue could be partially a poor install but you need to check for clogs within the air handler itself. That primary line isn't draining for a reason, either a lack of trap is causing the issue or there is a clog. Dirt/dust can buid up and block the drain line. BE SURE to turn off the power if you open up the air handler.

Good luck

Last edited by Ralph III; 04-04-2012 at 09:32 AM.
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Old 04-04-2012, 10:32 AM   #11
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Condensate Drain Line Mystery (pan full but no primary clog?)


Nope. Main drain lines are required by code to tie into the plumbing vent stack. Secondaries run outside.

You keep saying air handler. It's a vertical upflow furnace with a box coil, no p trap required. There is no negative pressure on the drain such as there is in an actual air handler as the blower is located after the evaporator and thus sucks the air through versus pushing it through.
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Old 04-04-2012, 10:55 AM   #12
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Condensate Drain Line Mystery (pan full but no primary clog?)


You are right on, Doc. The positive pressure from the blower will keep the line clean and when not cooling dry it out helping to prevent mold and algae growth in the line. The other thing is to keep that line sloped toward its drain point. I can't stress that enough. Just last week I tore out the condensate system from three units in an upstairs maintenance room and re-did it. The schlocks ran the lines flat across the floor causing them to constantly plug up from standing water growing algae. Now there is constant slope all the way to the exit point and there should not be any problem with algae. The reason for a trap on a puller coil (one where the blower pulls the air over an evaporator coil) is to prevent the water collected in the pan from being pulled up and blown through the ductwork by the blower. The downside of traps in condensate lines is that water stands in them, collects dust, dirt and other organics and promotes algae and mold growth in the bowl of the trap and eventually the line plugs up, water runs out and I have to make a service call, make it right and take your money!!
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Old 04-04-2012, 12:12 PM   #13
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Condensate Drain Line Mystery (pan full but no primary clog?)


Quote:
Doc Holliday; "Nope. Main drain lines are required by code to tie into the plumbing vent stack. Secondaries run outside..."
Would you care to specify the code that states the main condensate line must tie into the plumbing!

Otherwise, explain why other professional HVAC technicians note that that indeed is not allowed in many/some jurisdictions. See HERE and HERE. Nor is it preferred for various reasons as they note.

You may also want to contact the inspection/permit departments (Public Works), HVAC installers and the municipalities in southern Alabama and southern Mississippi and educate them in this regards. As they obviously don't know code. I have a newer home, have renovated and sold two of my homes and currently have a renovated rental home. Each had a/c condensate lines that were drained directly outdoors, none tied into the sewer. All passed inspection and were done by professionals.

Here are a few quotes from the HVAC techs forum:
Quote:

* "In our area you cannot tie the condensate line into the sewer system anyway..."

* "from what I've read condensate lines should never be drained directly into sewer lines..."

* "it's a common sense issue. yes, you should NOT drain hvac stuff into sewage lines..."

* "if the line drains to outside and not a sewer (95% of installs where I am)..."

Here is another quote in answering this specific question as posed on Yahoo Answers.

Quote:
"Some municipalities prohibit condensate lines going into the sewer line..."

" Municipalities that do allow a condensate line to go into a sewer line require a sealed connection up to the point of a trap..."

Instead of simply choosing to undermine folks who are trying to give some advice, or worst case scenario you're propogating false information, why don't you instead offer the OP a solution.

I say they should insure they have a trap, irrespective of positive/negative, as many HVAC pros recommend as well, othewise as the units manufacturer specifies. They should check for a clog and properly re-do the secondary condensation line.

Have a great day.


P.S. You can go to the InterNachi HERE for a discussion on code, otherwise go HERE for the specific IRC code itself in regards to one and two family dwellings. "Condensate from all cooling coils or evaporators shall be conveyed from the drain pan outlet to an approved place of disposal". That can include directly outdoors to flower beds, yards or any municipality approved area. BTW, I re-confirmed that with our inspection/permit office. You can drain outdoors. In addition, they prohibit drainage into septic lines where septic tanks are in use.

Last edited by Ralph III; 04-04-2012 at 02:43 PM.
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Old 04-04-2012, 12:53 PM   #14
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Condensate Drain Line Mystery (pan full but no primary clog?)


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Old 04-04-2012, 03:31 PM   #15
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Condensate Drain Line Mystery (pan full but no primary clog?)


When in doubt,,,,always,always,always follow the equipment manufactuer's directions to the letter.
They have a full staff of engineers that make a lot more than you do and they are hired to do one thing.That is to design machines that work and don't end up costing the makers money.

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