Condensate Drain Issue

Deano · Sep 1, 2018

Had the salon air handler unit start overflowing two days ago. Blew the lines out but still leaking so yesterday I shop vacuumed them to back flush still leaking.
Today I replaced the complete line from salon to bilge, still leaking.
If I go to the bilge and draw on it ever so slightly water comes pouring out but doesn’t continue to run. It’s like I need to vent the line to get it to flow. The line is 1/2” id and has 4 ‘ of fall. I can run a cable all the way through with no obstruction.
Any thoughts?

psneeld · Sep 1, 2018

Mine had an ever so slight, barely visible rise out of the pan.

A bubble would form and while I can't say for sure, it seemed like the resistance formed by the bubble was enough to keep it from draining the pan.

I was able to get it flat enough to overcome the bubble...an alternative might have been to put a t in where the tubing formed the bubble...but I don't know if that would work.

Deano · Sep 1, 2018

Air seems to be the issue. I may try to back fill the entire line with water and add a trap on the end.
It’s odd that this issue come after several years of ownership.

Deano · Sep 1, 2018

Turning that unit off for the night Try again tomorrow. Wife not happy.

Comodave · Sep 2, 2018

Maybe a dip and then uphill somewhere in the hose? That might stop it from draining. It sounds like you have done reasonable things so far.

Lepke · Sep 2, 2018

It might be an air pressure problem. A slight difference in air pressure between the pan and the end of the tubing.

motion30 · Sep 2, 2018

Yes hoes need some sort of trap that way the weight of the water will overcome the suction of the blower.

Maerin · Sep 2, 2018

1st off, the line is pretty small diameter, it exacerbates any problem you may have with air. A line that small will have trouble draining by gravity unless there's a lot of fall in the line, even then it can become air bound. A larger diameter line allows air and water to cross paths/directions. Run it in 3/4 the problem will probably disappear. Hard pipe is better, it won't sag & create traps. You can clean the line till the cows come home and it won't drain if it's air locking. Of course it flows if you blow through it, you're changing the physics acting on the water column. A tee/vent may or may not help, then you're introducing a point of failure (overflow) if the line backs. Most marine condensate drains are open to the atmosphere, so the blower suction isn't an issue, but if its in a blower compartment you may be getting some negative pressure as others noted. A trap solves that. It may help to drop the line vertically right out of the drain connection then change to horizontal if you have the elevation, so if the line does air lock a bit, it'll build a bit of head in the drop to push the condensate past the air trap.

Deano · Sep 2, 2018

Put a small trap on this morning and it’s been fine all day. I’m not sure why this started happening since we’ve made no changes in that compartment in two years.

stubones99 · Sep 2, 2018

Maerin said:
1st off, the line is pretty small diameter, it exacerbates any problem you may have with air. A line that small will have trouble draining by gravity unless there's a lot of fall in the line, even then it can become air bound. A larger diameter line allows air and water to cross paths/directions. Run it in 3/4 the problem will probably disappear. Hard pipe is better, it won't sag & create traps. You can clean the line till the cows come home and it won't drain if it's air locking. Of course it flows if you blow through it, you're changing the physics acting on the water column. A tee/vent may or may not help, then you're introducing a point of failure (overflow) if the line backs. Most marine condensate drains are open to the atmosphere, so the blower suction isn't an issue, but if its in a blower compartment you may be getting some negative pressure as others noted. A trap solves that. It may help to drop the line vertically right out of the drain connection then change to horizontal if you have the elevation, so if the line does air lock a bit, it'll build a bit of head in the drop to push the condensate past the air trap.

To test the possibility that you have reverse airflow combatting the drain flow, put the end of the hose in a cup of water. If that stops the problem, the cup will overflow, if not you don't have enough drop to compete with the vacuum of the blower.

Gordon J · Sep 2, 2018

How do folks keep their condenser drain line clean? I just had two overflow. After freeing the blockage I pour a half gallon of vinegar into each pan. I am thinking that might not be good enough

Deano · Sep 3, 2018

Peroxide and bleach

Gordon J · Sep 3, 2018

A friend used bleach in his, and it destroyed the aluminum fins on the condenser.

stubones99 · Sep 3, 2018

The safest natural solution (currently) is white vinegar. Put a cup of it in each drip pan every month. Clorox bleach can corrode aluminum.

Maerin · Sep 3, 2018

Look for Nu-Calgon products. They make condensate pan tabs, pads, that are all easy to apply and won't damage the coils. They also make evap cleaners that are good for cleaning a dirty coil. Don't try to mechanically clean (brush, scraper, etc) a coil, you'll just damage it and make it worse. Use a foaming, self-rinsing spray, the condensate will rinse it off, it will get deep into the coil to give it a thorough cleaning. These products are much better suited than home-grown application of household chemicals. Bleach in particular.

CaptRowlands · Sep 17, 2018

I have used bromine tablets to keep both drain and supply lines clear of organic growth. Much less caustic than chlorine or bleach and available from spa supply shops. Drop a few tabs in the strainer and drip try as experience dictates.

rgano · Sep 17, 2018

Living in buzillion percent humidity here, we all learn quickly to use pan tabs both in house and boat. Came home many years ago to a house (on slab) with 1/4 inch of water throughout when the a/c pan over flowed for just a day!

Symphony · Sep 18, 2018

time to move to more northerly climes, Rich!

rgano · Sep 18, 2018

I need to become a reverse snowbird! :socool:

sdowney717 · Sep 18, 2018

I use that hard clear plastic 1/2" polyethylene tubing It is a straight drop then makes a gradual turn and runs about 10 foot for both being a split system with 2 evaporators you have 2 drain lines. Not had any clogging yet. Simply joined together with short rubber hose sections. The ends dump direct into the shower drain, a square bucket really, which is wide open on top. Simply, it is an old 5 gallon gas can with top cut off and a 300 gpm Rule pump screwed on the bottom.
I wonder if your dumping into a sealed top container, dose that cause a backup? are those things vented?
Before I had the boat, the AC drain water was just dumping into the bilge.
Whatever I had before, it was nasty dirty, and was also broken, the pump did not pump out the shower water. I tossed it all and started over. what I have now is easy to clean and was cheap to make, basically free, I had all those pieces given to me as dumpster finds at the marina. That marina crushed a lot of old boats, and most of it went to a landfill.

Condensate Drain Issue

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