AC Condensate slime question (ME)

Mike T., Swampeast MO

Is the only thing I've found that works, but it has to be added regularly. I'm a partner in a bar and can speak greatly of the slime that forms in ice sink drains. It can completely clog a 3/4" i.d. tube in just a couple of weeks. It takes much, much longer to form in the condensate drains from the bar coolers. My guess is that just enough food (sugar) makes it into the ice sinks to let it grow explosively.

It's worst in summer when the cold water is surrounded by relatively warm air.

Have tried very hot (from a coffee maker) water to no avail.

I've added a tee with a filler inlet (not glued) to every A/C evap I maintain. A cup of bleech every couple months works wonders. In this area we tend to get a growth of a black-green slime on A/C evaps as well. I have to spray them regularly with bleach (to kill), brush with a big, soft BBQ brush, then flush with evap cleaner.

Probably half of the basements I visit in the summer have a trail of water leading from the furnace to the nearest floor drain. Every business with ceiling-mount units has water stains. Precious few above-grade units have an overflow pan (with the proper shut-down switch).

The absolute worst drains I've seen are done in 1/2" soft copper. Once clogged they're very difficult to clean. I pipe BOTH evaporater drains with 1" pvc, then drain these to a 1 1/2" dedicated (and vented) branch. Above grade I ALWAYS use an overflow pan and condenser float kill switch. I wire the switch through a DPDT relay to TWO neon lights in a prominent position. Yellow or green for OK; red for "clean me 'cause I'm not working." As a bonus, these little neon lights often make great nightlights.

Photo below by the little sink in my big closet.

Mark Eatherton1

What can a homeowner do to keep a AC coil condensate line clear.

This question was posed to me, and I didn't have a good answer. Is there something a homeowner can do on their own to maintain a drain on one of these beasts? I am not familiar enough to say. I have an idea of some things that would probably work (bromine tablets in the drain pan), but I really don't know.

Anyone?

TIA

ME

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Jeff Lawrence_24

Drain Pan Tablets

When I do a PM on a system, I put pan tabs in the drain pan. The directions say put them far away from the actual drain opening. I do that, but also put a couple either in the drain line itself or in the opening from the pan. I will also make sure the line is clear by blowing it out or using a vaccum outside. I will also put a couple of tabs in the condensate pump if I can.

I tell the homeowners to pour a couple of tablespoons of bleach into a Tee fitting in the drain line (I'll install one if I have to) about every 3-4 weeks, providing they aren't using the condensate water to irrigate plants.

Hope this helps.

J.

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John Felciano

I've seen

that drain slime in the traps of ice tray drains.You know the ones in a bar where they keep the ice for mixing drinks.(not that I've spent any time in bars,or under bars)As I understand it it's some kind of cold water bacteria that forms something that looks like jelly.A daily shot of bleach seems to keep it under control.Bleach tablets work too,but I wonder if tablets in the trap will break down the plastic pipe?

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ScottMP

how about

a bucket of hot water ??

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Mike T., Swampeast MO

Bleach

Is the only thing I've found that works, but it has to be added regularly. I'm a partner in a bar and can speak greatly of the slime that forms in ice sink drains. It can completely clog a 3/4" i.d. tube in just a couple of weeks. It takes much, much longer to form in the condensate drains from the bar coolers. My guess is that just enough food (sugar) makes it into the ice sinks to let it grow explosively.

It's worst in summer when the cold water is surrounded by relatively warm air.

Have tried very hot (from a coffee maker) water to no avail.

I've added a tee with a filler inlet (not glued) to every A/C evap I maintain. A cup of bleech every couple months works wonders. In this area we tend to get a growth of a black-green slime on A/C evaps as well. I have to spray them regularly with bleach (to kill), brush with a big, soft BBQ brush, then flush with evap cleaner.

Probably half of the basements I visit in the summer have a trail of water leading from the furnace to the nearest floor drain. Every business with ceiling-mount units has water stains. Precious few above-grade units have an overflow pan (with the proper shut-down switch).

The absolute worst drains I've seen are done in 1/2" soft copper. Once clogged they're very difficult to clean. I pipe BOTH evaporater drains with 1" pvc, then drain these to a 1 1/2" dedicated (and vented) branch. Above grade I ALWAYS use an overflow pan and condenser float kill switch. I wire the switch through a DPDT relay to TWO neon lights in a prominent position. Yellow or green for OK; red for "clean me 'cause I'm not working." As a bonus, these little neon lights often make great nightlights.

Photo below by the little sink in my big closet.

Earthfire

Indicators

This I really like . Will have to BORROW your idea.

Earthfire

black Muck

The stuff has a nasty habit of closing back up if you ream it or blow thru it just like snaking a grease clog in a kitchen drain . Pan treatment and routine bleach and flushing to keep the line flowing is necessary .I do try to minimise bleach contact with the evaporator coil as much as possibile and rinse thoroughly when it happens.

Mike T., Swampeast MO

Use good, encapsulated, plug-in relay

The coil will be de-energized only when there is water in the pan. (At least that's the only way I've figured out the circuit.) About 6 years on one with no faults--others newer and no problems either.

chris smith

do the same

the brand of tablets i use is "actabs" they work pretty well also if you clean the evap regularly with chems it greatly reduces this problem

chris smith

chris smith

black muck

> The stuff has a nasty habit of closing back up if

> you ream it or blow thru it just like snaking a

> grease clog in a kitchen drain . Pan treatment

> and routine bleach and flushing to keep the line

> flowing is necessary .I do try to minimise bleach

> contact with the evaporator coil as much as

> possibile and rinse thoroughly when it happens.

chris smith

black muck

i have a sludge sucker rig on my nitrogen bottle for the muck cause your right its got to go

chris smith

Mark Eatherton1

Thanks everyone!!

You've been extremely helpful. your responses will be part of a Q and A for Fine Home Building magazine.

ME

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BillW@honeywell

The slime

Two possibilities. I've seen a drain pan outlet that has a cleanout on it, you just remove the plug, and use a bottle brush to clean inside. I can't remember the brand, but I've seen them at Johnstone Supply. An Ultraviolet light, placed above the A coil will bombard the area with intense UV rays, killing the slime in the pan; our model is a UV100A1059, available from any Honeywell PerfectClimate distributor.

ScottMP

funny

we just got a call this morning for a backed up condensate line. Guess I'll have to get some tablets. We may have to use some chemicals to get it moving.

Scott

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jpatterson

drain sludge

we have used a product called the algae-gator to prevent drain blockages. It is an inline canister that holds tablets to prevent the buildup.

Aidan (UK)

Does anyone know what this organism is?

It sounds like pseudomonas, which has been causing big problems with a few chilled water systems in London. It can also cause pneumonia and is a lethal complication in (I think)cystic fibrosis.

The link was the most informative I could find on Google, but it doesn't tell you how to deal with it. Any more information would be welcomed.
This might be the next legionnaires disease type scare.

http://www.hbi.co.uk/news/pseudomas.htm

Aidan (UK)

typo

That name should have been Pseudonomas aeruginosa.

BillW@honeywell

Pseudomonas

Along with Legionella, is one of the most common HVAC-related pathogens. The stuff is virtually everywhere...all it needs is something to eat and a moisture source, and it will grow. Proper coil design works best,a carefully pitched pan, a generous sized drain pipe, to a condensate pump, that dumps it outside or into a drain. The ductwork should have access for cleaing & servicing. Avoid having the condensate drain into the space between the floating slab & the wall, pump it out. A combination of good coil design and installation, ultraviolet germ killing lights, electronic air cleaner or advanced media filter and spot chemical treatments as needed will probably work best to minimize problems. Good PM and elimination of ALL water leaks is vital. IMHO, 90% of IAQ problems are directly related to water leaks, either into ductwork or walls from plumbing, leaky tub tiles, roof or wall leaks.

BillW@honeywell

Germs, Algae & Slime (OH,MY!)

I forgot to mention that only a trained biologist or other medical-type technician in a lab can accurately identify exactly what you may have growing in there. They take a sample, grow it in a dish, look at it under a microscope & identify it. They send you a written report as to what they found, and depending on the lab, what might help minimize it.

don_9

Drain problem

anyone ever try a fluidic flow device,can only be used
for draw-through units.
it operates virtually void of maintenance efforts and
free of the many problems caused by condensate trap.
Is not affected by algae growth,eliminates condensate over-
flow caused by trap blockage,prevents condensate blow thru.
also helps out on negative pressure inside the system.
solve a few pressure problem i had on a few rooftop units.