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Old 09-06-2009, 02:47 AM   #1
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AC Coil drain pipe questions


Hello,

I'm hoping someone can tell me a little more about the pipes attached to my AC Coil.

I'm assuming these are pipes to drain the condensation from the drip-pan. But, why are there two of them??

As best as I can tell, one of them (Pipe 'A' in the photo) goes down an interior wall next to a vent pipe for my bathroom sink. I'm assuming the pipe links into the sink's drain pipe down below somewhere (someplace in the wall - I can't see it)

The other pipe (Pipe 'B' in the attached photo) goes outdoors - it terminates just below the eaves of my home.

Also, there is an open tee connector on pipe 'A'. I can see a trickle of water running down the pipe through the opening (so it appears to be draining ok). Should there be a plug in this open tee? A lot of cold air is blowing out of it. I've also heard of systems that have a 'float' switch that will turn the AC off if the drain pipe gets backed up - is this where a float switch would go?

Any information or advice on these parts would be appreciated.

Thanks!
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Old 09-06-2009, 03:33 AM   #2
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AC Coil drain pipe questions


appears to be condensate drains. i would seal the tee (not permanently). I am HVAC certified have been for 12 years. I service and repair large commericial units on offshore drilling rigs. We keep the drains sealed up unless we need to clean the piping. The main reason is if you get a clogged drain, you want it to back up in your air handler, not outside of a drip pan. Especially if it is upstairs above a ceiling. All that lint and debris the filters don't catch will eventually create a slime in your drain and clog it over the years. They make tablets (grainger) that you can put in the drip line of your coil to reduce the chances of a clog.

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Old 09-06-2009, 03:35 AM   #3
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one more thing i forgot to mention, you are paying for that cold air that is coming out of the tee
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Old 09-06-2009, 04:09 AM   #4
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AC Coil drain pipe questions


you need a trap on one of those pipes and cap off the one going outside.your blowing conditioned air out of them and probably water out of the pan and on top of that heat exchanger just below the pipes.water on top of a galvinized metal heat exchanger is leading to a new furnace in your future.if you have a service company have them repipe the one with the tee on it and install a trap.if you want to use the piping that goes outside they can put a pan under the unit then pipe that outside to the eaves...if water is dripping out of the eaves pipe then the main pan in the unit is blocked.the trapping of the condensate will seal the air from discharging out and guarantee an even condensate flow out of the pan above that heat x
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Old 09-06-2009, 04:48 AM   #5
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thanks biggles I forgot about the trap. we have out traps "below deck" . We especially don't have furnaces, either on the rig or where i live. I do a little hvac residential work for family, but that's it. There is a lot i have forgotten over the last 10 years. We don't fall under the same codes residential or commercial. We have our own marine codes. The only codes i keep up with as far as residential are electrical. It's amazing how you can go to school to learn something and forgot little by little by little over the years if you don't utilize it. I guess, unless it's a no brainer, i am through giving any hvac advice. I don't want to steer anyone the wrong way. Have a good day and God Bless.
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Old 09-06-2009, 01:49 PM   #6
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AC Coil drain pipe questions


Thanks for the info fellas!

It seems every time I go into my attic I come across something new that wasn't done the right way the first time... My house is only 10 years old - you would think things would be a little more up-to-snuff.

Maybe I'll stop going into the attic.

I totally agree that I'm wasting perfectly good cold air by blowing it into the attic, or down the pipes. A 'trap' seems like a great idea.

Let me see if I got this right... You recommend a trap on one of the condensate pipes, and to cap the other one off...

A few questions:

1. You recommended capping off the pipe with the Tee (Pipe 'A'), but that is the one that apparently drains into the interior drain. Shouldn't I cap off the one going outside (Pipe 'B' - the one without the Tee), and then install the trap into the pipe that currently has the tee (and apparently drains to the same drain as my sink)?

2. If I cap off one of the condensate pipes - would you recommend I connect a float-switch there to turn off the unit if the other pipe backs up? such as this one: http://www.toolsdirect.com/little-gi...LAID=343732699

3. Is this 'trap' the same concept as a sink trap? Simply a 'U' shape bend in the pipe to trap water and prevent gasses (in this case, cold air) from escaping? Can you provide any links to what this should look like?

4. How would I install a pan under the entire unit? Would I have to jack it up an inch or two and then slide the pan under it? Sounds like a pretty tricky job (I've included a wide angle photo to show what I'm working with)

Thanks for your help! you guys are awesome!
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Old 09-06-2009, 03:27 PM   #7
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The top pipe of the two is an overflow drain which is supposed to drain if the other fails. I also recommend an overflow pan under the furnace. I would at least use a wet switch that would shut down the ac if it senses water. I do not know what the building codes are in your area, but the plumbing on your furnace is awful. I do not think that gas line should be ran across the front of the furnace. Around here the flexible range connectors are not allowed on furnaces. Those drain lines appear to have been run by someone inexperienced. That romex wire feeding the power to the furnace should be in a conduit. Also the class B vent pipe need to have an inch clearance to combustibles. It appears it is connected to a roof truss, could be a fire hazard. Flex duct is OK but I don't like to see it used as a trunk line. I'm not trying to pick your furnace install apart, just my opinions and observances.
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Old 09-06-2009, 05:04 PM   #8
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AC Coil drain pipe questions


Thanks Skip!,

I appreciate your (and everyone else's) input on this. Please do pick apart the installation. That's the only way I'm going to know how it should be done right. Our nickname for the builder of the home 'Short-cut', so I'm not surprised that his subcontactors also did shoddy jobs - you should see some of the other electrical around here - someone must have bribed the inspector

For reference, I'm located in the Los Angeles, CA area.

I may tackle some of the improvements myself (when it cools off a bit ), or get someone else to look at it. It is interesting that I've had two HVAC guys 'inspect and tune' my AC unit in the past few years and neither of them pointed out any of these issues (neither of them was the installer of the unit - so they had nobody to protect).

You've brought up several other issues here, so I'll ask a few more questions about them (and give them new numbers for easy reference)

QUESTION #5. I hadn't thought about the power to the unit - I agree that should be in a conduit - I can handle rewiring that. I'll have to figure out how I want to run the conduit - not much around the unit for support. Any suggestions on how to run the conduit? I can run power under the floor and come up next to the unit.

QUESTION #6 The gas line is an atrocity. The solid pipe extends horizontally about 4 feet from it's point of support (and about 1 foot in front of the furnace) to the valve where it connects to the flex pipe. No support there whatsoever. I was going to install a vertical 2x4 near the valve and secure it there for more support. Do you have other suggestions?


The class B vent is spaced away from the roof truss by about an inch. The installer drove 2 nails into the roof truss - leaving about 1 inch exposed. The vent pipe is resting against those nails and is held in using the metal strap you see in the photo. I was wondering why those nails were there acting as spacers, and you answered that question. It certainly not the most elegant solution, but it appears to meet the 1-inch clearance requirement.


Thanks again to everyone - and I look forward to other thoughts on questions 1-6 above and how I can improve the quality of this installation.
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Old 09-06-2009, 05:17 PM   #9
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AC Coil drain pipe questions


... one other thing - I think the flex pipe on the gas line may be a building code requirement. Here in California the ground moves and shakes every so often. The flex pipe would allow the connection to absorb some of that movement.

That's just a guess - I'll have to see if I can find the codes for this sort of thing.
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Old 09-06-2009, 05:26 PM   #10
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the emergency pan would be 3" deep ,and say 3" from the actual unit all the way around with a 3/4 brazed female pipe thread adapter(thread in a 3/4 PVC adapter slip X mpt) then recut the line going outside to the eave no trap required.when youv lift the unit that +3" to slip the pan in pull the pan foward so you can access the fan section and slip 4 rubber isolating pads so the unit is off the pan.now if you see water coming out of the eavedrain the main is blocked up (probably at that new trap you installed) and brings you up into the attic.it looks like the right side PVC goes outside?...drop that to the floor with no rise all the way out to the eave drop out line.the trap should be right off the unit as close as possible.remove the unvented line and put a 3/4 plug in there and drop it down to the emergency pan,and Yes the trap is the same principle as a sink or house trap.
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Old 09-11-2009, 03:20 PM   #11
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AC Coil drain pipe questions


Thanks for the additional details!

I've got a bit of work to do in sealing some of the leaks in my ductwork - once that project is done I'll start re-piping the condensate and installing a drip-tray. Getting the drip tray under the unit is going to be a challenge...

I'm considering one of these EZ-Trap condensate traps on the main drain, and a float-switch on the overflow drain.
http://www.airtecproducts.com/EZ_Trap.html

Anyone have experience with EZ-Trap's products? good? bad?


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Old 06-07-2010, 02:06 AM   #12
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I just had a new a/c system installed. My drain pipe drains on the ground. Question, the first tech placed a trap facing up and it made a clunking sound. Later after the system froze up and the second tech came along with the first tech they disagreed on which way the trap should be turned. They finally turned the trap down. Is this right or do I even need a trap sinse it's not going into a septic system at all only the ground?
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Old 06-07-2010, 04:54 AM   #13
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Trap should face down. As in the gully of the trap is the lowest part of it.

Without the trap, you blow lots of air out of the drain. It becomes a small waste of your cooling bill.

The drain should be ran out of your basement/crawlspace. Its adding humidity to it. And some of that humidity is getting back into your house. And your paying to remove it again.
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Old 11-12-2010, 12:18 PM   #14
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I have 10 air handling units attached to a common condesate pipe. The drain pan overflows in some units when the ahu is subjected to a shut down. there is a trap at the end of the condensate main pipe. tell me the defect
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Old 11-12-2010, 03:51 PM   #15
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fritzy, the install is a mess! first, typically the drain on left is the primary drain and does need a trap. IF you are interested in a float switch I use the ez-trap ezt-210 Second, the drain on the right is the secondary (overflow) drain. it is usually higher that the primary or has some plastic on the inside covering half the hole. This is not necessary if using the fore mentioned trap. However, I would also agree that since this install was in your attic, that it have a secondary pan that the unit sits in with that drain attached to it.

Safdar, Each ahu needs to have a trap, however, after the trap it need to be vented because there is a second trap that you mentioned. You can not double trap a drain, it will not flow. You accomplish the vent by installing a tee facing up after the trap and put a short riser in the open end of tee.


On our installs and tune-ups we also install unions so that the drain can be removed and blown through to ensure its not plugged. always remember you need to have fall the entire length of the run, stagnant water grows algae and other biologicals

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