Do drains need to vent?

Hello Pete,

I wondered if the drain off my system is correct? The T-fillting that I have circled in red, it this correct or necessary? This pipe goes into my housing drain system. Does it need to vent for some reason? There is also another drain, I guess maybe a back up, that goes out the soffit.

Also, where the two blue arrows are, should there be cold air pouring out here?


Thank you

 

Yes, leave the stub-up open to the atmosphere to provide help with drainage - otherwise it would be like trying to pour water out of a bottle without a vent to allow air in to fill in the void. That's why a gas can has a vent that can be opened up. What little bit of conditioned air is released into the attic at the refrigerant liquid line grommet and the PVC condensate opening is insignificant and should not be a concern. .

The bottom-most drain is your primary condensate drain line and condensate is usually forced out by the positive pressure of the air handle blower. That condensate drain line is usually the only one that has a stub-up or an opening to the atmosphere to help with drainage but also an opening to pour hydrogen peroxide or white vinegar to dissolve gunk and algae buildup from clogging the drain.

Some people use bleach but hydrogen peroxide is just as good and less messy to deal with. A couple cups of hydrogen peroxide should be poured into the PVC opening once every 2-3 months during A/C season to clear the drain line from clogging. I suggest turning Off the HVAC system at the thermostat for 15-20 minutes to allow the hydrogen peroxide to do its job, then turn the HVAC system back On.

You can buy a few 32oz bottles of hydrogen peroxide for $1 each at Walmart. Buy a cheap plastic funnel at an auto parts store and you've got what is needed to take good care of the condensate drain line.

The upper-most drain is your secondary or emergency condensate drain line in case the primary drain line gets clogged up. If you ever see water coming out of the drain under your soffit you'll know that your primary drain line is clogged up and needs to be cleared as soon as possible.

As an aside, you should clean out the sawdust and debris from the emergency overflow pan so it doesn't get clogged up.

 

You can seal the small copper pipe grommet with electricians putty.
Since you have air coming out of that fitting.... your system is running under positive pressure.
That means you can cap that opening and the water will still drain.
You can use a short stub of 3/4" PVC and a cap. No glue.

 

glwjr - Do you know where the primary condensate line drains to? Does it drain into the drain underneath a bathroom lavatory I (like the image below)?

If your condensate line drains underneath a bathroom lavatory you do not want to cap the PVC stub-up because the positive air pressure blowing into the lavatory drain above the p-trap will tend to bog down and slow the draining of water from the lavatory, and it will make a gurgling noise from the drain stopper whenever the air-handler blower is running. If the condensate line drains underneath a bathroom lavatory you'll want to leave the PVC stub-up open - vented to the atmosphere just like any other plumbing drain system needs vented.

 

PJmax Kooter Thank you very much Gentlemen, The trap at the bottom of the sink where the system drains was clogged with gunk. This is the second sink in the guest bathroom. It rarely get used. The other sink is used quite often. So as Kooter mentioned it was probably algae build up from the drainage.

I agree the little bit of air loss isn't significant, Just wasn't sure if it was normal. Now I know.
I like and appreciate the tip on peroxide. I never knew this. This is why you guys are the PROS!

Thank you again!