Flushing AC Unit

[jayerose]

After pouring white vinegar down the line, how many of you pour hot water down right after the vinegar?

If you do, how long do you wait for the hot water?

thank you!

[MrFlorida]

I just use hot water every month or so.

[Babubhat]

Hot water is sufficient

[MSchad]

Our AC tech told us not to use vinegar. Just hot water with a few drops of dawn dishwasher detergent.

[retiredguy123]

If you really want to flush out the condensate line, buy one of these. It does a better job than hot water or vinegar.

Amazon.com (https://www.amazon.com/Drain-King-345-Bathroom-Condensation/dp/B001ATBS4W/ref=sr_1_8?crid=3EKI128LNSRU7&keywords=drain+king&qid=1665149806&qu=eyJxc2MiOiIzLjg0IiwicXNhIjoiMy4yMSIsInFzcCI6IjM uMDkifQ%3D%3D&sprefix=Drain+king%2Caps%2C132&sr=8-8)

[vintageogauge]

We have a service contract with Munn's, they come every six month to inspect and service our unit as well as the thermostat and air handler. They told us just to use hot water and they do a more complete clean-out when they do their service. Well worth the minimal cost to have peace of mind.

[Kenswing]

Our AC tech told us not to use vinegar. Just hot water with a few drops of dawn dishwasher detergent.

Ours told us the same thing. Although I can’t find anything that says vinegar will damage pvc. I just flush with hot water every month now.

[RICH1]

Shop vac on the outside pvc drain tube ….. vinegar/ bleach is fine ..I was an AC guy, now I’m old, grey, and don’t feeling like doing anything

[TommyT]

I use a very small bottle of bleach and chase it with a gallon of HOT water every six months. For me it works great. I can use a flashlight to look into the drain and it's pretty clean and clear. A little staining on the sides of the pipe but that's all..

[New Englander]

I fill a pail with about a gallon or so of hot water and a dash of soap. use a funnel and pour it down the drain. Then I rinse the soap residue out of the pail and fill it with just hot water and pour that down the drain. I do this a few times a year.

[Altavia]

Ours told us the same thing. Although I can’t find anything that says vinegar will damage pvc. I just flush with hot water every month now.

I think the risk is damage if vinegar/bleach gets into metal parts of the HVAC drain pan.

[Stu from NYC]

We have a service contract with Munn's, they come every six month to inspect and service our unit as well as the thermostat and air handler. They told us just to use hot water and they do a more complete clean-out when they do their service. Well worth the minimal cost to have peace of mind.

Same with us.

[Bill14564]

We have used both but not at the same time.

- The idea behind vinegar is to raise the acidity and kill any slime growing in the lines. The argument against vinegar is that it is harmful to aluminum and as it evaporates in the line the vapor could come back into your air handler. It seems like that would be a very tiny risk at best, but that's the argument. Pouring water after the vinegar would dilute the acidity and the effectiveness.

- A gallon of hot water works both to kill anything with the heat and to flush it out with the volume. This seems to make sense, is pretty simple, and costs less than vinegar (save a few pennies)

- A hose attachment to force water through the line would certainly provide the volume and the pressure could be enough to clear a buildup. I would be concerned about creating a leak in a place I cannot reach to fix but PVC is strong enough so that really shouldn't happen. Munn's used this technique on my system during their maintenance visit.

- A shop vac pulling from the outside to clear a blocked line seems like the safest approach to clearing a clogged line. However, it would be best to use one of the three above to prevent the line from becoming clogged in the first place.

[Full-timer]

After pouring white vinegar down the line, how many of you pour hot water down right after the vinegar?

If you do, how long do you wait for the hot water?

thank you!
why flush the vinegar out? it will in no way harm the drain and the longer it stays in the pipe, the more work it will do.

[Golfer222]

Where is the drain located that you pour the hot water in?

[retiredguy123]

Where is the drain located that you pour the hot water in?
It is located next to your furnace or air handling unit inside your house, probably in the garage. There is a white plastic pipe that comes off of the unit to drain the condensate water from the evaporator coil. You need to twist and pull off the cap on the pipe and use a funnel to pour water into the drain pipe. The cap is located about a foot or so from the air handling unit.

[Michael G.]

Munn's for us also using a shop vac with water.
They said just use hot water once a month.

Now my neighbors use bleach in their water line.
The only thing people don't like with bleach is the smell in ventilation system.

[retiredguy123]

Munn's for us also using a shop vac with water.
They said just use hot water once a month.

Now my neighbors use bleach in their water line.
The only thing people don't like with bleach is the smell in ventilation system.
Bleach can create fumes that can cause erosion of the metal parts in your air handing unit, especially the evaporator coil. I would not use bleach, unless you thoroughly flush it out with water after adding the bleach to the drain.

[Golfer222]

It is located next to your furnace or air handling unit inside your house, probably in the garage. There is a white plastic pipe that comes off of the unit to drain the condensate water from the evaporator coil. You need to twist and pull off the cap on the pipe and use a funnel to pour water into the drain pipe. The cap is located about a foot or so from the air handling unit.

Where the does the water come out?

[retiredguy123]

Where the does the water come out?
The water will come out of another plastic pipe outside of your house, most likely located behind the garage. There will be 2 pipes sticking up out of the ground, and you should see water dripping out of one of the pipes whenever your air conditioner is running. The other pipe is connected to the drain pan located under your water heater, if you have a tank type water heater. Water will only come out of that pipe if your water heater has a leak or the pressure relief valve trips. Note, that you may only have one outside pipe if you have a tankless water heater.

[Kenswing]

Where the does the water come out?

Ours comes out a pipe that is located right next to the ac unit behind the garage.

[Golfer222]

Thanks- very helpful

[Keefelane66]

Ours told us the same thing. Although I can’t find anything that says vinegar will damage pvc. I just flush with hot water every month now.
Vinegar is perfectly good can be used as mold remover and also as a fabric softerer.

[Hape2Bhr]

Be careful with using vinegar if your exit drain is near grass or plants. Some are susceptible to damage.

[sdeikenberry]

If you really want to flush out the condensate line, buy one of these. It does a better job than hot water or vinegar.

Amazon.com (https://www.amazon.com/Drain-King-345-Bathroom-Condensation/dp/B001ATBS4W/ref=sr_1_8?crid=3EKI128LNSRU7&keywords=drain+king&qid=1665149806&qu=eyJxc2MiOiIzLjg0IiwicXNhIjoiMy4yMSIsInFzcCI6IjM uMDkifQ%3D%3D&sprefix=Drain+king%2Caps%2C132&sr=8-8)

Those do work, but you have to stop the backflow into the HVAC drain pan so that all the water's force goes out the drain line. To do that effectively you need a valve in the pipe between the hook up of the hose and the HVAC drainpan.

[GaryKoca]

I have a contract with Sun Kool and they said the same thing. Just use hot water every few months. No Dawn or vinegar.

[Worldseries27]

why flush the vinegar out? It will in no way harm the drain and the longer it stays in the pipe, the more work it will do.
i vinegar for half hour, figure its done it's job, then flush with hot water monthly. Make sure hvac off at either switch or thermostat before starting this proceedure

[Annie66]

Some years ago, I purchased a flexible hose at Lowes that fits nicely inside the inner diameter of the PVC drain line. I also installed a screen mesh over the outside end of the drain line to prevent insects and small critters from taking up residence inside the drain line.

I connected a female fitting on one end of the flexible hose. I then remove the PVC cap on the drain line and slide approximately 3 feet of hose inside the drain line. I then connect the other end of the flexible hose to the water hose. I remove the screening mesh and slowly crack open the bib valve to flush the line. I then reinstall the screening on the outside end of the drain line, remove the hose and reinstall the drain line cap. It takes about 10 minutes start to finish. Easy-peasy.

[Rwirish]

Hot water only no vinegar.

[WingedFoot78]

I was told to pour hot water mixed with some Dawn liquid every month or so.

[retiredguy123]

Those do work, but you have to stop the backflow into the HVAC drain pan so that all the water's force goes out the drain line. To do that effectively you need a valve in the pipe between the hook up of the hose and the HVAC drainpan.
I guess that depends on the arrangement of the piping. On my unit, the rubber part of the device extends a few inches into the vertical exit part of the drain pipe. It seals off the horizontal drain connection from the AC unit. There is no way for any backflow to occur. The water can only go directly into the drain pipe and to the outside of the house.

On most units I have seen, there are 3 pipe connections above the vertical exit pipe. None of those 3 joints are glued together, so you can easily remove any part of the drain assembly to add water or to flush the system.

[Sunflower33]

After pouring white vinegar down the line, how many of you pour hot water down right after the vinegar?

If you do, how long do you wait for the hot water?

thank you!

I was told only warm water. Never vinegar. I use warm water only and I’ve done this for 15 years and no problems

[Lindaws]

Right after, no wait

[retiredguy123]

Right after, no wait
It seems to me, that if you flush with water immediately after adding vinegar, you defeat the purpose of using the vinegar at all. The vinegar is gone, and it doesn't have any time to kill mold or anything else.

[G.R.I.T.S.]

After pouring white vinegar down the line, how many of you pour hot water down right after the vinegar?

If you do, how long do you wait for the hot water?

thank you!

Don’t use vinegar! Use up to a gallon of boiling water.

[Ltwise3500]

The same here. Vinegar is not good for this system.

[Runner187]

After pouring white vinegar down the line, how many of you pour hot water down right after the vinegar?

If you do, how long do you wait for the hot water?

thank you!
Recommended use is 3 parts warm water with 1 part of vinegar. Mix, pour into drain line.

[Kenswing]

The same here. Vinegar is not good for this system.

Can you tell me why vinegar is bad for the system? I can’t find anything that contraindicates on the internet. I just keep hearing not to use it.

[Tvflguy]

This Thread is a perfect example of…. Ask a question and get a multitude of answers.

Perhaps none in particular is wrong or right, but can be mighty confusing.

Just sayin’.

[villager7591]

Munn's told me warm-to-hot water once a month. Shut off A/C and air handler at the circuit box first. Then pour slowly. I was informed to pour 1 gallon per month.

[bark4me]

Dawn dish soap will absolutely 100% clog your drain pipe. My last tenant did that and caused one hell of clog and mess!

[bark4me]

Vinegar or a water/bleach mixture will not hurt your pipes.

[PersonOfInterest]

2 shots of Tequilla, 2 oz of Lime Juice, 1 shot triplesec, mix in shaker with ice before pouring. THEN grab a gallon of hot water and dump it down the tube.

[PJ_Smiley]

I bought the cheapest garden hose I could find (an old worn out hose would work as well) and cut it short (2-3 feet) on the end with the connector to the hose bib. I connect it to my regular hose with a pistol nozzle (threaded on spray end). Shove short hose down drain and squeeze nozzle with as much or little pressure as needed to flush A/C drain. I picked this tip up when I saw Munn's A/C guy use this to flush A/C on service call.

[Bill14564]

Can you tell me why vinegar is bad for the system? I can’t find anything that contraindicates on the internet. I just keep hearing not to use it.

The theory is the fumes from the vinegar will come back up the drain tube and into your air handler where they will hurt the coils.

- Are you pouring enough vinegar to make many fumes?
- Is the vinegar concentrated enough after dilution with the water in the drain to make fumes?
- Are the fumes lighter than air such that they will work their way back up the tube?
- Is your house cool/warm enough that the air handler will not come on and disperse any possible fumes throughout the house before they can become concentrated enough to hurt the coils?

It's a theory, it makes some sense, it doesn't seem likely to really cause a problem. On the other hand, hot water is just as easy and a few pennies cheaper.

[TomPerry]

I think the risk is damage if vinegar/bleach gets into metal parts of the HVAC drain pan.
What metal parts? The drain pipe is all PVC all the way to ground outside.

[retiredguy123]

What metal parts? The drain pipe is all PVC all the way to ground outside.
Fumes that can back up into the AC unit.

[jimkerr]

Vinegar and caustic chemicals like bleach are a no no. Just flush with water and also suck it out with a wet vac. That’s all you need to do.