I did most of my work in the Chicago area where it is also humid. Yes gunk, algae, and even legionnaires disease can grow in stagnant water. Typically the A/C coil has a pan meant/designed to drain. Outside of the unit PVC piping is routed to a drain somewhere. If the coil is on the suction side of the blower; one must install a trap (otherwise the "suction" of the blower will not allow the condensate to drain out). If the coil is on the pressure side of the blower; no trap is required but you will be blowing treated air out of the drain pipe. Personally I always install an upright TEE after the trap for venting the drain line and "blowing" gunk out of the drain line without having to go to a lot of trouble. I've never heard of vacuum cleaner action on a drain line, i dont believe that i've ever left a drain line on site that could be accessed. Yes vinigar, a mild acid, will help to prevent things from growing.

 

They sell tablets you can toss in the internal pan if you're getting overwhelmed with gunk clogging the drain.

The best thing is to brush the trap if it's accessible.

 

Proper trap and line sloped to termination point reduces fouling potential.
Proper filtration also helps.

 

look for any papers that were left with the appliance. You should have the user's manual and possibly the installation guide. A drain pan overflowing is a bad sign, especially on a new unit. You should call the contractor and make them repipe the drain properly.

 

Thanks! I did not get any manuals except one for the thermostat. I will call tomorrow and ask for one. Good idea.

Would the overflowing be from the drain pan? I was trying to locate it to see if there's water in it, but I'm not sure where it is. The air handler is in a closet in my house. Maybe I have to unbolt the grill that's under it.

The drain pipe goes through the slab to outside. It's been there since the house was built in the eighties. I'm assuming that repiping would be a major undertaking.

When I vacuumed it from outside, a bunch of gunk came out, so it was probably clogged. When I call tomorrow, I'm going to ask if, when they installed the system two months ago, they vacuumed out the line.

I really appreciate your taking the time to respond. I know nothing about HVAC, which I'm sure is obvious, so it's frustrating.

 

It is my understanding that code requires the manuals be given to the owner.

 

and the EPA doesn't allow releasing refrigerant!

 

You need to chase and annoy the crap out of the installer. If they tied into an old condensate drain they should have made sure that the pipe was "as new". You paid for a properly working drain, the best and easiest time to replace that old pipe is right after they demo the old unit. ARE we talking 3/4" white PVC? or a worthless piece of galvanized pipe which obviously needed replacement.

 

Yes, it's PVC. That would have been great to have what's there replaced, but it didn't even occur to me. Probably because it's in or under the slab, so it didn't seem like a possibility.

I have a list of questions to ask when I call tomorrow, and that will be on it.

I'd think that having it overflow after two months would indicate a problem. However, maybe in Florida in the summer you have to vacuum it out monthly. Or maybe when they installed the new system they didn't do that, so it was last done in April.

 

The infamous Florida megga trap. I hear they require constant treatment.

 

Would be curious to see after vacuumed out, how much water it holds before beginning to drain. Could give some indication if pipe is sloped properly.

 

I always assumed the water went right from the air handler out the pipe to the outside drain. Is that not right? It's dripping most of the time.

 

If I understand correctly the pipe goes down from the air handler under the slab and then comes up out of the ground so the entire section under the slab is full of water and plugs up with biological growth.

 

My dad used to ALWAYS forget to leave thw manuals with the equipment.
Nowadays, it's easy to just download the pdf from the manufacturer.
I second the recommendation to get the drain "trap" vacuumed thoroughly, heck, I'd flush it with a garden hose to be sure the gunk gets washed out.
Then have the enzyme pan treatment tablets installed, and treat the entire line...
That mess is just a problem waiting to happen.
You may want to abandon it and have a new above slab line installed.

 

A nonsloped drain line can create a running trap that fouls xxx time faster than a properly installed trap and sloped line.

 

Stumpdigger, where is the trap located? Is it something I as a homeowner can locate? Or is it internal?

In my community, a lot of the condensate lines are under the slab.

 

On yours The trap will be under the slab which isn't a good design but I hear it's very common in florida. Do you see any way to run a drain line to the outside possibly that it could be sloped properly?

 

vstech,

I put a Shopvac on the drain outside and vacuumed it. A bunch of gunk came out. Then I poured a cup of vinegar into the drain line (through the T that has the cap on it), let it sit a few minutes, then turned the Shopvac back on and ran it while I poured about a quart of water through it. More gunk came out.

I'm looking at it, and I don't see a trap, which I would assume is like a P-trap on a drain. I'd post a photo, but I don't see how to do that.

When I call the installer today, I will ask about the enzyme treatment. And the new line, although that seems like it would be complicated, getting behind a lot of walls.

 

R600a, my air handler isn't on an outside wall. It looks like the line would have to go behind two walls, taking two right-angle turns. And I'm assuming the work would have to be done from the other side, which means cutting into a bathroom wall.

 

Dear Masscom; while your condensate line makes absolutely no sense it still may be true. I just cant see why, the original installer is punching holes thru the wall for refrigerant lines, what's one more for the condensate.?
keep in touch and let us know of your progress. the people on this site have a collective of thousands of years of experience and work with quality contractors.
i installed an A/C system in an old house that i bought in 1988, when i sold it in 2021 i had never had to clean the condensate drain or add refrigerant.

 

Dear Masscom; while your condensate line makes absolutely no sense it still may be true. I just cant see why, the original installer is punching holes thru the wall for refrigerant lines, what's one more for the condensate.?
keep in touch and let us know of your progress. the people on this site have a collective of thousands of years of experience and work with quality contractors.

My understanding is they run the condensate and line set under the slab. It's a horrible mess for many reasons but supposedly very common down there.

 

I would pour bleach in it, let it sit, dont flush it out, spend days or weeks until it comes out clean; after that you can probably neglect it for a decade but better to keep it clean.

 

My air handler overflowed today. New unit installed two months ago. I vacuumed out the condensate line (and there was some gunk in there). How often do I need to do this? Does it help to pour in some vinegar every month? I'm in Florida, where it's 1000 degrees, if that figures in. Thank you!

I've told you a million times not to exaggerate. :grin2:

 

Thanks, Stumpdigger and everyone else who's weighed in! The installer is sending a technician out tomorrow to clean the line with some stuff made for that purpose and also check out if the air handler is level, why the float switch didn't turn off the system, if the drain line is sloped, if anything is going on with the drain pan, etc. He took my concern seriously. He said to allow an hour, because he really wanted him to look into it. He also said, "Those drain lines under slabs are the bane of my existence."


All the great input from this group helped me tremendously in talking to him. I will definitely post what happens.

 

No bleach , no vinegar , no drain opener either. All of them are not suitable for AC drain treatment or clogging remedies. All of them are corrosive especially to copper.
Pushing with nitrogen some times is disastrous with old thin wall pvc. or installer miss a joint with no glue on it .Sucked with shop vac is the safest and worked for me every time,and don't forget to prime the p trap if any/sarcastic/ but seen them missing at all.Give yor customer few extra pan treatment tabs and recommend to drop one in the pan when they replacing their air filter. Today even they can buy tablets at home depot.

 

THIS!!!
I AM APPALLED AT THE RESPONSES ON THIS FORUM RECOMMENDING CHEMICALS
Yeah... vinegar likely wouldn't hurt the equipment, but it wouldn't clear the line either...
Bleach... no... just no. So bad for equipment.
NEVER use drain cleaner chemicals...
Specific condensate treatment solutions are best to keep a line clear, but they won't do much for an existing clog.
Gotta vacuum it out with a shop vac...

 

The technician came out today and put some product in the line, let it sit for 20 minutes, then added a bunch of hot water and vacuumed it out. He said there was no way to see if the line was sloped correctly since it was under the slab. He checked the float valve and said it was working fine, so he wasn't sure why it didn't turn off the system. I suggested he adjust the line going to it so it sloped down, which he did. He said he couldn't see the drain pan. He said the air handler was level. Apparently, this is a really common problem in Florida -- buried drain lines that get clogged. Maybe this cleaning and putting in vinegar once a month and continuing with my twice-yearly maintenance will mean no more problems. If not, he said since the air handler has a bathroom between it and the outside, putting in a new line would be a major deal. What they usually do is install a pump. He wasn't suggesting that, since that's another piece of equipment to deal with. I kind of feel like I didn't get anything more than what I could have done myself, especially since he had to use my Shopvac. He did spend quite a while looking over everything. Maybe that's all there is to do. Anyway, I said I'd post an update, so here it is.

 

The technician came out today and put some product in the line, let it sit for 20 minutes, then added a bunch of hot water and vacuumed it out. He said there was no way to see if the line was sloped correctly since it was under the slab. He checked the float valve and said it was working fine, so he wasn't sure why it didn't turn off the system. I suggested he adjust the line going to it so it sloped down, which he did. He said he couldn't see the drain pan. He said the air handler was level. Apparently, this is a really common problem in Florida -- buried drain lines that get clogged. Maybe this cleaning and putting in vinegar once a month and continuing with my twice-yearly maintenance will mean no more problems. If not, he said since the air handler has a bathroom between it and the outside, putting in a new line would be a major deal. What they usually do is install a pump. He wasn't suggesting that, since that's another piece of equipment to deal with. I kind of feel like I didn't get anything more than what I could have done myself, especially since he had to use my Shopvac. He did spend quite a while looking over everything. Maybe that's all there is to do. Anyway, I said I'd post an update, so here it is.

You didn't read obviously what HVAC professionals said about vinegar or any other chemicals ?

 

Can test slope by vacuuming the measuring amount of water added before starting to drain. Won’t tell amount of slope, but will the amount of sag.