My AC unit is about 5 years old. When I had it installed they replaced everything from the flange above the air handler on back including the drain line.

The other day the thermostat went blank a few times for a short time before turning back on. Turns out the drain line is backing up and the float swich was cutting the system off.

Not a big deal, I've had this issue with my old system. I used my shop vac to vacuum out the built up gunk in the drain line so the problem is resolved.

Is there a specific chemical that I can use to treat the drain line to prevent the build up from occurring? I'm thinking to pour a cup or 2 of bleach into the drain line every so often, is there something else I should use instead?

yep bleach will do it. You can buy bleach tablets.

Hydrogen peroxide works well too. Not a bad idea to inspect the end of the line outside of the house too, “things” love to nest in there, especially when the AC hasn’t been running a while.

My HV guy left me some anti algae solution to pour in once per month when I change the filter. Works well. I cannot recall the name.{He mixed it up in a Powerade bottle.} It is more effective than bleach and nontoxic. Bleach can harm PVC.

Have used this and it works great. Completely non-corrosive with no smell...

https://www.diversitech.com/en-US/item/id/19129

My hvac tech said vinegar would work with a good hot water rinse afterwards. I’ve also used simple green and on a rare occasion bleach but with a really good rinse afterwards.

quote:

Originally posted by cne32507:
yep bleach will do it. You can buy bleach tablets.

^^^^^^^^^
This. I haven’t used the tablets but a 1/4 cup of bleach may do the trick.

Hydrex pan tablets (first URL I posted also listed Gasex, LOL)

quote:

Originally posted by ZSMICHAEL:
My HV guy left me some anti algae solution to pour in once per month when I change the filter. Works well. I cannot recall the name.{He mixed it up in a Powerade bottle.} It is more effective than bleach and nontoxic. Bleach can harm PVC.

Bleach does not harm PVC.

When we had this same issue, I was told not to use bleach to clear the line, but instead to use white vinegar every 3 months. Also use an air compressor if you have it to blow out the line every 3 months.

Thanks for the input. I think I am going to go with liquid bleach. I plan on using 1 cup of bleach cut 50/50 with water about every 3 months and see how that works. We use the A/C almost all year so The bleach will be flushed out relatively quickly. I am considering the tablets but the liquid will be way easier since I have a port in the drain line.

StorminNormin, i used my air compressor on the old system untill an A/C guy hooked up a shop vac to the discharge and sucked it out. Easy and works great. I picked up an adapter that goes from the vac hose size down to the drain pipe diameter.

I pour a cup or so of bleach down my drain line every spring and fall. Haven't had any issues for years.

Bleach

quote:

Originally posted by houndawg:

quote:

Originally posted by ZSMICHAEL:
My HV guy left me some anti algae solution to pour in once per month when I change the filter. Works well. I cannot recall the name.{He mixed it up in a Powerade bottle.} It is more effective than bleach and nontoxic. Bleach can harm PVC.

Bleach does not harm PVC.

No, but the fumes and/or bleach severely harm the aluminum coils on the air handler if exposed. I wouldn't use it. Vinegar is much milder and doesn't hurt the aluminum coils.

quote:

Originally posted by jimmy123x:

No, but the fumes and/or bleach severely harm the aluminum coils on the air handler if exposed. I wouldn't use it. Vinegar is much milder and doesn't hurt the aluminum coils.

Correct recommendation, but wrong in how you arrived at the solution.

Does bleach hurt aluminum? No
https://www.google.com/search?...rome-mobile&ie=UTF-8

Does bleach hurt copper? Yes
https://www.google.com/search?...0i20i263.Gj61GOGWfeI

I had my regular service done on my AC today and talked with the tech about this. They recommend 2 tablespoons of bleach or vinegar in 1 cup of water once a month. I was surprised at the amount and he said it doesn’t take much to keep it clean He said the only reason they recommend one over the other is if there is carpet near the unit they recommend vinegar instead of bleach in case you spill some.

When they installed the system they installed a port in the drain line specifically for this so there is no aluminum or copper involved, just the pvc drain line.

quote:

Originally posted by SpinZone:
When they installed the system they installed a port in the drain line specifically for this so there is no aluminum or copper involved, just the pvc drain line.

Mine's the same way. I keep a small funnel stored up in the attic next to the port, which makes it easy to just climb up there with a bottle of bleach and pour some in. (But even if I were to spill a little, it's all just plywood and PVC in that area.)

Yes, you're adding it to the pvc drain piping. But the vapor fumes is the factor.

quote:

Originally posted by Excam_Man:
Yes, you're adding it to the pvc drain piping. But the vapor fumes is the factor.

I never considered that.

The fumes are not an issue . The bleach is in the drain line , far removed from any coils , etc. and it's really a small quantity anyway .