Furnace leak when running AC unit.

[lbartowski]

My furnace has 2 threaded, female-type hubs on it, about 3 feet off the floor. One has a connector screwed into it that attaches to a plastic drain line hose that runs into the drain in the floor. The other has nothing in it...but is leaking water out of it when I run the AC. Why would it do that? Can I just plug the other hold with putty? Any advice is appreciated.

[heaterman]

Assuming this is a downflow and it's the coil that is 3 feet above the floor with the furnace on top, the second hole is most likely a secondary drain tap, which depending on you application should be plumbed to a drain as well. Pics might help........................

[Adnshel]

Yeah, if you can supply pictures we can help you with the problem.
Which threaded fitting is on bottom, the plumbed one or the plugged one? The lower one should definitely be plumbed.

[lbartowski]

I don't have any pictures now. I'll try to post some when I get home. The hubs are side by side...not on top of one another. I've lived there 6 years and never had a problem until about a week ago.

[beenthere]

Have you had them serviced in the last 6 years.

May be a sign of a problem that could get worse if unattended to.

[fritzhvac]

Sounds like primary stopping up , and overflowing secondary... Get your service guy to take a look.

[lbartowski]

Couldn't I just open it up and clear out the primary myself?

[lbartowski]

No? Or should I call a service guy to do it?

[egads]

Well, telling you to do that, or how to do that would be dyi advise. It's against the rules here. And thanks for those pictures you promised. What these guys are saying is twofold. You have not given enough information for anyone to help you. And that A/C systems must be regularly serviced. Like your car. Driving it until it breaks is foolish. Especially considering how expensive both are to repair/replace.

I am not a HVAC contractor, but from reading here and observing installed units, the secondary, fail safe hole should also be plumbed. It is also normal now to have a sensor that would shut the unit down if the primary drain gets plugged. There have also been upgrades to how the primary is plumbed nowdays. Only a pro, standing at your house, looking at your install, can tell you what you really need.

[clarkie]

It sounds like the primary drain line is stopped up or clogged and the secondary line is not plumbed. Do not try to fix yourself since if you don't know exactly what you are doing, you could make the problem worse, either by breaking off the drain line and/or fitting. Call a reputable serviceman and have him take care of it correctly.

[the dangling wrangler]

Couldn't I just open it up and clear out the primary myself?

You absolutely could do that.
But,what if that isn't the problem?

[lbartowski]

You're right. In fact, I think I get my tranny replaced this weekend too...just in case.

[egads]

You're right. In fact, I think I get my tranny replaced this weekend too...just in case.

Come on now, it is very clear that this is not a dyi site. You may find that irritating, but it is what it is. I personally suggested maintenance not preemptive parts replacement. Modern stuff is complex, both cars and A/C systems. To put a point on it, here's another auto example: Modern cars require that their brake fluid be replaced on a time (not mileage) schedule. Now curmudgeons who used to have simple cars think this is bull. But those are the folks who then have to pay to replace an ABS controller costing up to a couple of grand. All because they would not pay the dealer $90. every few years or spend an afternoon in their driveway dyi. Because nobody is going to tell them what to do.

That extra hole is not supposed to just be open. The drain clogged for a reason. Dirty filter? complete lack of maintenance? Filthy coil? No one can see that over the internet.

[GREGHVACGUY]

Here is one way to look at it. You start your car 2 -6 times per day(depends on you driving). your furnace starts and stops 3 to 4 time hour times 24 hours = 72 to96 times a day. Would you drive you car for a year with out having the oil changed or put air in your tires. Most would say no so why not have a HVAC guy check your furnace or ac every year and make sure everything in tuned up and ready to go. If your car stops running you set at home or get a ride. Your furnace or ac stops you set at home cold or hot and wait for us to come and help. Just look at it from my eyes.

[fritzhvac]

Here is one way to look at it. You start your car 2 -6 times per day(depends on you driving). your furnace starts and stops 3 to 4 time hour times 24 hours = 72 to96 times a day. Would you drive you car for a year with out having the oil changed or put air in your tires. Most would say no so why not have a HVAC guy check your furnace or ac every year and make sure everything in tuned up and ready to go. If your car stops running you set at home or get a ride. Your furnace or ac stops you set at home cold or hot and wait for us to come and help. Just look at it from my eyes.

Hey GREGHVACGUY,that is a very good analogy on getting
preventative maintenance done!!! I hope you don't mind
if I use that one myself out in the field... FRITZ

[Erik HVAC]

That is for your secondary drain u can unscrew it and run pvc into your drain. Your secondary is if your primary drain gets clogged.