algae caused flood

[Jeff Ivers]

Went out in the garage Sunday afternoon to discover water pouring through the ceiling. Shut the upstairs a/c unit off since it is above garage and called repairman. Repairman arrived yesterday and determined that algae growth had completely clogged the condensate drain pipe, leading to water running down the inside of the heating unit, onto the floor and through the ceiling. I was advised to pull apart the condensate drain and pour diluted bleach through the drain pipe monthly for 3 months and then 2 a year. Wish I had known this before the ceilings of the garage and laundry room were damaged!

 

[4x4Pete]

It could also just have been dirt from the air settling in the drain line. The evap removes moisture from the air and also washes dust and stuff from the air, this gets trapped in the drain and sometimes causes blockage.
It's a normal maintenance procedure to clear and flush the drain line on all cooling equipment. This can even happen in your car!

 

[larry4406]

That trap on the AC coil causes lots of problems like that.

 

[Wayne67vert]

My a/c drain has a float switch to shut down the unit in case of a backup of water. It works. I had the unit shut down a couple of months ago. I cleaned the drain line and no issues since.

 

[vwpieces]

Common occurrence.
Buddy had a large puddle in his basement from an algae clog. Looked like a large hairball of nasty goop.
I now clear my drain pipes to pump every year before turning the AC unit on. I keep a couple of the PVC connections connected with only a press fit so it can be removed and easily checked. Probably should put a coupler on it for that reason but mine is also in the basement where no real damage will occur from a leak. I also clean the tank on pump and the pump itself annually.

 

[larry4406]

The unit at my house is a clear trap. There are red caps and a brush attached. Easy to see and clean.

 

[Jim greengo]

Blow it out with nitrogen once a year.

 

[rlitman]

Went out in the garage Sunday afternoon to discover water pouring through the ceiling. Shut the upstairs a/c unit off since it is above garage and called repairman. Repairman arrived yesterday and determined that algae growth had completely clogged the condensate drain pipe, leading to water running down the inside of the heating unit, onto the floor and through the ceiling. I was advised to pull apart the condensate drain and pour diluted bleach through the drain pipe monthly for 3 months and then 2 a year. Wish I had known this before the ceilings of the garage and laundry room were damaged!

Lousy advice. What you need is a secondary drain pan under the unit with a drain outlet and a water alarm. Anything less will lead to more ceiling repairs eventually.

 

[Jeepster04]

If possible, I put a shop vac on the outlet of the drain at least yearly and I also put tablets in the pan yearly. Keeps them nice and clear. So far no issues.

 

[gmcgeo]

I always pour some bleach in the pump ever year....... never had issues with back ups

 

[welder4956]

So maybe mine is not installed "correctly", but my condensate drains have no traps and have never clogged. The drains from the upstairs and downstairs units tee together in the basement and dump outside in the yard. I'm not seeing an incentive to install traps either from the posts here.

 

[Jeff Ivers]

My a/c drain has a float switch to shut down the unit in case of a backup of water. It works. I had the unit shut down a couple of months ago. I cleaned the drain line and no issues since.

This unit also has a float switch. It was totally dry. The backup occurred below the coil pan and float switch.

 

[Jeff Ivers]

So maybe mine is not installed "correctly", but my condensate drains have no traps and have never clogged. The drains from the upstairs and downstairs units tee together in the basement and dump outside in the yard. I'm not seeing an incentive to install traps either from the posts here.

I have lived here 30 years and the upstairs unit has been replaced twice. This is the first time this has happened. Don't have a clue as to why an algae block occurred now - the tech describe the algae clot as looking like snot. Perhaps just a fluke of something blowing through the outside air making it into the coil drain area and the excessive and sustained heat - who knows? I wish this unit was installed with a drain pan under the entire unit instead of just a drain pan built in under the coil. but it is not installed that way and I will not spend the money having the unit pulled and reinstalled to achieve that until it fails again,

 

[larry4406]

So maybe mine is not installed "correctly", but my condensate drains have no traps and have never clogged. The drains from the upstairs and downstairs units tee together in the basement and dump outside in the yard. I'm not seeing an incentive to install traps either from the posts here.

With no traps you are blowing conditioned air (and condensate) continuously down the drain. So you have a loss of paid for conditioned air meaning it’s not going where you intended. If it goes into an interior floor drain it’s still inside the thermal envelope. But certain to not have a trap clog on you.

One of my houses the damn thing clogged and unfinished basement got wet. I removed the trap and let it blow down to the floor drain.

 

[quickfarms]

I had the drain line pop off of one of my mini split cassette units this year and drip on the floor. No damage except some water on the floor and I had to crawl around the attic to fix the issue. I think it may have been dislodged when they installed the third head last summer. Now I keep an eye on the discharge line outside the house

 

[MongoTA]

Went out in the garage Sunday afternoon to discover water pouring through the ceiling. Shut the upstairs a/c unit off since it is above garage and called repairman. Repairman arrived yesterday and determined that algae growth had completely clogged the condensate drain pipe, leading to water running down the inside of the heating unit, onto the floor and through the ceiling. I was advised to pull apart the condensate drain and pour diluted bleach through the drain pipe monthly for 3 months and then 2 a year. Wish I had known this before the ceilings of the garage and laundry room were damaged!

I had the same experience as Wayne maybe 2 years ago. Upstairs AC (20+ years old) would not kick on. Electrical all good. Air handler is in the attic, behind a kneewall, but still inside the thermal envelope of the house. Opened the kneewall door to see the drain pan that the air handler was sitting in was full of condensate. Float switch did its thing.

Same problem, the drain was clogged with goopy algae snot. Cleaned it out. No problems since.

 

[dogdog]

They have tablets treatments for that I think if your environment foster that much bacteria growth. All I remember it was blue in color.
just google hvac drain pan tablet.

something like this.

https://www.amazon.com/dp/B000KM3BUY/?tag=atomicindus08-20

 

[fitter30]

Traps are only used when the coil is on the suction side of the blower. They have to deeper than the negative pressure of the blower to over come the negative. Float switch should be mounted in the overflow pan

 

[mike93lx]

Traps are only used when the coil is on the suction side of the blower. They have to deeper than the negative pressure of the blower to over come the negative. Float switch should be mounted in the overflow pan

Interesting. My units all have traps and the coils are downstream of the blower. I have drain pans on all, but not alarms (yet)

 

[larry4406]

Traps are only used when the coil is on the suction side of the blower. They have to deeper than the negative pressure of the blower to over come the negative. Float switch should be mounted in the overflow pan

All of our new construction homes have a trap for the coil condensate and all of the coils are downstream of the blower. We do have pans and float switch.

 

[welder4956]

Good information here on the need for p-traps: https://hvacbasics.com/condensate-drains-and-traps/

My units have a gas furnace upstream of the AC coil and are positive pressure, so the only downside is a minor loss of conditioned air through the 3/4" drain line. I'm willing to live with that to avoid clogs. I was not aware that there are negative pressure units and see where a p-trap makes sense on a negative pressure unit.

 

[PoorUB]

Traps are only used when the coil is on the suction side of the blower. They have to deeper than the negative pressure of the blower to over come the negative. Float switch should be mounted in the overflow pan

Interesting. My units all have traps and the coils are downstream of the blower. I have drain pans on all, but not alarms (yet)

In our area the HVAC inspector requires traps on all HVAC drains.

 

[gmcgeo]

In our area the HVAC inspector requires traps on all HVAC drains.

same

 

[fitter30]

If a trap is used it needs a vent on the leaving side of the trap. Install the trap for easy cleaning because dirt and slime will build up at the bottom of trap.