Gurgling Sink Drain?

[Travelover]

Bird, could you put some plastic wrap over the sink drain and see if you have a positive or negative pressure? Might help in the diagnosis.

 

[Redneck in training]

Bird, could you put some plastic wrap over the sink drain and see if you have a positive or negative pressure? Might help in the diagnosis.

That is a great idea. Need to remember that one. :thumbsup:

 

[kenstrac]

In post 15+16 is the answer to your problem.
In the cooling mode there is sufficient condensate to keep water in the trap on the A/C unit, when you change over to heat mode there is no longer any condensate and the water in the trap eventually evaporates allowing the air to move freely down the drain pipe to cause the gurgling.
To check this you can plug the drain TEMPORALY with a stopper or rag or pour enough water in the drain to fill the trap.

 

[Bird]

Bird, could you put some plastic wrap over the sink drain and see if you have a positive or negative pressure? Might help in the diagnosis.

Plastic wrap over the drains in both sinks are definitely pushed (or sucked) down into the drain when the heat comes on.

To check this you can plug the drain TEMPORALY with a stopper or rag or pour enough water in the drain to fill the trap.

I reckon I'll go back up in the attic in a few minutes.

 

[Bird]

Ken, once again it appears that you (and SandburRanch) may have hit on the right thing. I poured about a cup and a half of water in that HVAC condensation drain and no more gurgle in the sink, at least for the first cycle. With our old HVAC system, that little P trap was downstream from the "standpipe?" in which I periodically put a little bleach, but with this new system, they put the P trap upstream and I hadn't really noticed it. But if you pour enough water in fast enough, it'll get back to the P trap.

 

[kenstrac]

Ken, once again it appears that you may have hit on the right thing. I poured about a cup and a half of water in that HVAC condensation drain and no more gurgle in the sink, at least for the first cycle. With our old HVAC system, that little P trap was downstream from the "standpipe?" in which I periodically put a little bleach, but with this new system, they put the P trap upstream and I hadn't really noticed it. But if you pour enough water in fast enough, it'll get back to the P trap.

Going back many years ago we had units mounted on roof and I would add anti freeze in the trap to keep them from splitting in the winter.
When spring arrived and we checked the units for A/C I noticed that the anti freeze was still in the trap and had not evaporated,you might try adding some in the trap to see if that dosn't slow down or eliminate the trap from going dry.

 

[FastPauly]

Yikes.....looking at the piping pic, sighting across the bottom of the drain pipe to the top of the trap appears to be awfully close to the same level. Not much of a trap.....is it?

 

[Bird]

Going back many years ago we had units mounted on roof and I would add anti freeze in the trap to keep them from splitting in the winter.
When spring arrived and we checked the units for A/C I noticed that the anti freeze was still in the trap and had not evaporated,you might try adding some in the trap to see if that dosn't slow down or eliminate the trap from going dry.

I've known of stopped up drains ruining ceilings, so I normally put a little bleach in there once a month, at least during the summer, but I'll likely try the anti-freeze now.

Not much of a trap.....is it?

That's just what I've always thought.

 

[ametcalf]

I just saw this old post but wanted to address the problem you had and may still have. I think the gurgling was a blessing in disguise because it made you aware of what could be a serious problem and that is having the condensate drain from the A/C system tied into the sewer drain system without an air gap. It has been many years since I was in the plumbing business but if my memory serves me correct when the original problem arose in the 1970s with Legionnaires' disease they never for sure nailed the problem down but a common factor in locations where it reared its ugly head was a cross connection between plumbing drain and vent systems and air conditioning systems. I don't know what the plumbing code is in Texas and I haven't kept up my plumbing licenses but in the 1970s the plumbing code in Kentucky would not have allowed your condensate to connect to your sewer drain the way you describe. I would do what I need to do to get rid of that connection. If you are interested in more information pm me or add to this post and I will try to give a more complete explanation.

 

[Xfaxman]

I just saw this old post but wanted to address the problem you had and may still have. I think the gurgling was a blessing in disguise because it made you aware of what could be a serious problem and that is having the condensate drain from the A/C system tied into the sewer drain system without an air gap. -------------a cross connection between plumbing drain and vent systems and air conditioning systems.-----------in the 1970s the plumbing code in Kentucky would not have allowed your condensate to connect to your sewer drain the way you describe. I would do what I need to do to get rid of that connection. If you are interested in more information pm me or add to this post and I will try to give a more complete explanation.

My system is plumbed to the septic line.

Can you explain "air gap"?