water drain on Central Heat and Air Indoor Unit


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Old 06-26-12, 09:07 PM
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Question water drain on Central Heat and Air Indoor Unit

I have a Heatpump type central AC that has a drain attached to the bottom of the indoor unit. the water is under no pressure and usually just drips out. It connects by schedule 40 to a Plastic drain pipe of about 3 inches in diameter. this pipe goes into the cement slab foundation and exists behind my house. The indoor unit rests on a platform above the floor. the 1" pvc is connected to a connector at the bottom of the ac . this pipe is connects to the 3" pipep in the floor. This 3" drain is on the other side of the AC and the pipe makes many twists and turns before it gets to the drain. just Before it enters the drain there there is a rectangular trap made up of 4 elbows.

This 1" pvc pipe gets stopped up several times a year and soaks the closet its in and my hall carpet also. That's the only way I know it's stopped up.

What I want to know is: Is this trap necessary? Can I just clamp a piece of flexible vinyl tubing to a stub of 1" pvc pipe and place it in the 3" drain? Would it eventually stop up the 3" drain and I have bigger mess to repair? I have a bucket under there now to catch the water and the water looks so clean and pure, I don't see how it could stop anything up.
Thanks,
Paul
 
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Old 06-26-12, 09:18 PM
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Yes, you must have a ptrap for the unit to drain because the evaporator coil is before the fan and under negative pressure.

You can install a pvc union to allow you to remove and clean out the drain once or twice a year.

 
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Old 06-26-12, 09:46 PM
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Thanks for replying. Even if the drain is just to the outside of the house and is not connected to the sewer system at all do I still have to have that trap? Also, what would make the drain stop up? The water seems so clean and pure. After all it's just condensed from the air.
 
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Old 06-26-12, 09:54 PM
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The blower would pull return air through the drain.
Like sucking a soda through a straw, water would flow uphill.
 
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Old 06-26-12, 09:55 PM
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I think I ought to explain that the 3" drain is not a sewege drain it is just a three inch pipe that also carries the freon(both Hi and Lo, I think) to the outside unit. I have the condensate driping into a bucket right now and cannot understand why it is under any pressure. The sheet steel walls of the unit are not air tight I don't think, because I have had the cover off several times with the unit running.
 
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Old 06-26-12, 10:06 PM
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I work on air handlers daily that have no return air duct at all. (common return)
They will not drain (into the drainline) without a ptrap.

If you know the make and first 4 digits of the air handler model number you can probably look up the manual. It will tell you if your unit requires the trap for proper drainage.

If your evaporator coil is after the fan as in gas heating, a trap is not required for your application.
 
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Old 06-26-12, 10:28 PM
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If your evaporator coil is after the fan as in gas heating, a trap is not required for your application.
No my unit is a Heatpump. My last house had a central unit with gas heat and I never had this problem. Personally I hate these things! nothing but trouble!

You're the expert, and I don't mean to question your expertise, but if it needed the trap to drain, why is it draining into a bucket now? Forgive my stupidity, I'm just a homeowner, my experience lies with electronics and computers.
Thanks,
Paul
 
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Old 06-26-12, 10:51 PM
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I cannot see your application but it would require a very small amount of negative pressure to prevent proper drainge while the unit is running.

I run around -.02 to -.05" wc when I hold a manometer probe under the unit and my air handlers will not drain properly without a trap.

The risk of water damage would be present without a ptrap.
It is your home and your money. Therefore it is your decision.

My professional advice is to use a trap with draw through coils.
I'd lose the home made trap and buy a regular 3/4" pvc trap and add a cleanout for service.
 
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Old 06-27-12, 05:25 AM
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Well it seems like I can't avoid the trap. The construction company who built the house either installed the original ac system or contracted it out the house is now about 15r old. I recently had a whole new unit installed and the installer just reconnected the old drain system.

Could I use the flex tubing and splice a trap into that. Would Lowes or Home Depot havew a trap especially for that purpose?

I was thinking of just putting a hose clamp around the vinyl to PVC join using two other clamps to fasten the trap with a short piece of vinyl to go into the drain. Would the vinyl section have to be level where it connects to the trap?

Also if you could put a name to this drainage contraption I could maybe google it and maybe find something readymade.
Thanks,
Paul
 
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Old 06-27-12, 03:24 PM
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OK just to follow up on this. I flushed out the old Rube Goldberg contraption with a wate hose out side. I got a coupler for 23 cents and rejoined the pip and put the other end in the 3" drain with p-trap intact. I just hope it works and that the 3" pipe is not what's stopped up.

Thanks for your help! I have learned a thing or two!
Paul
 
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Old 06-27-12, 03:37 PM
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Is that a normal/common setup? Every house I've ever lived in and every family/friend's unit I've ever had reason to work on has had the A coil in the supply plenum under positive pressure. I don't think I've ever seen it before the blower, and I can't see a drain line working at all under negative pressure, trap or no trap.
 
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Old 06-27-12, 03:50 PM
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p3aul, from what I'm visualizing you have the 3" pipe acting like a conduit - basically it's a sleeve for the refrigerant/drain/low voltage lines.. The 1" pipe doesn't actually drain into the 3", the 1" line runs inside the 3" and dumps outside the house, correct?

If you do in fact need it (and for a unit that drains outside you shouldn't) Big Orange or Blue will have a pre-formed one-piece PVC trap that should be less prone to clogging than the square trap you have now.

I also found this - call the EZ Trap, which looks nice because you can stick a brush in it to clean it out, but I don't know if it's worth $50.. You can make one yourself with a couple bucks worth of fittings.

 
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Old 06-27-12, 07:50 PM
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JerseyMatt
p3aul, from what I'm visualizing you have the 3" pipe acting like a conduit - basically it's a sleeve for the refrigerant/drain/low voltage lines.. The 1" pipe doesn't actually drain into the 3", the 1" line runs inside the 3" and dumps outside the house, correct?


JerseyMatt: Thanks for joining the group. I really have a strange setup here let me see if I can describe it:

I have a convoluted system of pvc pipe that ends in a sqare trap that then just lays inside the pipe. There is no connection to another 3/4" pipe inside the pipe(not that I can see). You're right the hi and lo tubing and the low voltage tube do go into this 3 inch pipe that goes thu my slab out to patio in back. Now here is where it gets weird. outise near the AC outdoor unit the tubing and cable come up out of the ground( 3" pipe visible). Near this a 3/4" pvc comes up out of the ground and ends in a reverse of the p-trap. withe end pointing toward the ground. It's very confusing.
My builder is still around town and I have emailed his office requesting a schematic of the drain he had to have built in the slab himself. I'm going to follow up with a visit to his office tomorrow. If the 3/4 pvc line goining thru the 3" line I can't see it. The drain has always just lain in the entrance to the 3" pipe.
 
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Old 06-28-12, 08:49 AM
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That sounds so wrong I don't even know where to begin. If it's coming up out of the ground (not horizontally out the side of the house), that means the whole thing is trapping water - since water can't flow uphill. We really need pictures of this.
 
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Old 06-28-12, 01:46 PM
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OK here are the pics. The first pic is outside near the outdoor unit. I have drawn a red circle where the low-voltage and the freon comes up out of the ground. The large pipe in the middle is the dryer exaust the small 3/4 pvc pipe I drew a blue circle around is the condensate drain. The other pic is the inside unit at the drain pan. The third pic is the floor showing the p-trap and where the drain just lays inside the 3" pipe. Since the whole 3"pipe is buried outside at the outdoor unit I can't tell how this arrangement actually is. It's been working fine for 15 years. I've owned the house for 10 years. I replaced the inside and outside unit 2 years ago. The guy who replaced the units just reattached the original drain pipe.
Paul
 
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Old 06-28-12, 04:50 PM
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I have no idea what they did but it's absolutely and totally wrong. That never should've passed an inspection. How far above the top of the outside "u-turn" is the floor that the air handler is sitting on? Basically what you have is a pipe that sits full of water, and it grows mold and scum that'll keep clogging it - not to mention it probably freezes during the winter. Is there any way that you could route a new drain that just pokes out the side of the house?
 
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Old 06-28-12, 11:04 PM
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[QUOTEI have no idea what they did but it's absolutely and totally wrong. That never should've passed an inspection. How far above the top of the outside "u-turn" is the floor that the air handler is sitting on? Basically what you have is a pipe that sits full of water, and it grows mold and scum that'll keep clogging it - not to mention it probably freezes during the winter. Is there any way that you could route a new drain that just pokes out the side of the house?

][/QUOTE]

I called the builder this afternoon. He tried to tell me that they could do what they wanted there was no codes! I informed him differently and he got a bit hostile. These houses are not cheap but they are cheaply built. I did my homework after I bought the house(unfortunately) and asked around. My next door neigbor had to redo here drive. Seems it was sinking into the pit where the builder dug a hole to bury left-over construction stuff! He's right, I have no recourse now, not after 13 years. He said, "Well it passed inspection", but inspection here is a joke they get away with what ever they want. It apt to freeze. I live in central Georgia where we had one day last winter that got below 32 degrees!
The house is on a slab and the unit sits in the center of the house. I suspect what they've done is the 3" pipe is just a short stub that goes through slab and the freon lines just go under ground to exit at the outside unit. The stub proable terminates in asome gravel that absorbs the moisture. the outside 3/4" pipe is probably just for show as there is no moisture coming out of it.
 
 

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