airflow in the secondary drain line

[dgreenb]

I'm getting a completely new A/C install done to my house, ducts and all. I was looking over the work they've done so far and I noticed that cold air was coming out of the secondary condensate drain line. The primary one seemed to be okay. I pointed this out to the install tech this morning and he told me that this is "normal" and the airflow "helps to push the water out".

Needless to say, this didn't pass the smell test to me (reeks of bull), but being a mere mortal homeowner I didn't have the info to call him on it. Seems to me that ANY leaks of cold air is a "Bad Thing" as that escaped air as to be resupplied by something.

Also, the cold air through the drain pipe is causing the line to sweat a bit, I can imagine that wherever it'll touch something, more condensate will form. Also bad, I think.

So, with all the experience on this board, am I being fed som bull?

Thanks,
-Dave

[chandleraz_guy]

Not a pro but I noticed the same thing on my primary line for 2 new units.... Hopefully they installed a j-trap with an automatic shutoff in case the primary line gets clogged.

I read somewhere on here were j-traps need to be primed so I primed mine which solved the air problem in and prevents anything nasty from going in too.

I also purge my lines out from time-time via a special vacuum attachment from where the lines drain outside. (vacuum them out & re-prime w/water)

My AH is located in unconditioned attic and lines drain to the outside but I suspect your system is different? My humidity level outside is usually under 10 percent and inside is about 30 percent--I get no condensation output usually till the evening when I suspect the weather changes?

What sort of system, brand, and unit location are we talking about?

[RoBoTeq]

If the unit is within the conditioned area of the home, it makes no difference. If in an unconditioned area, you will lose a small, very small, amount of cooling and heating through this drain opening.

You are not being fed a line of bull. This is standard industry practice with very little used remedies.

[dash]

One remedy is a float switch,which would also turn off the unit if the drain overflowed.I'd ask them how much to have one added.

[mark beiser]

Within the last year we started installing an EZ-Trap float switch in the secondary drain outlet on all of our installs. Solves 2 problems with one fix.

We trap the primary, regardless of if it is a pull through or blow through coil.

[t527ed]

even though it may feel like a lot of air coming out the drain in the overall air flow capacity of a system it is nothing.

[acmech13]

don't you have some kind of vent for your attic? im sure more air infiltrates that way.

[RoBoTeq]

don't you have some kind of vent for your attic? im sure more air infiltrates that way.

How does air infiltrate from an attic vent?

[acmech13]

air will infiltrate into the attic from an attic vent. thats its job to let the heat out. Yet in doing so air also has to be able to come back in. yes or no. Im not talking about when the fan is running. when its off in the winter will air come in. I know sometimes when im under one i can feel a draft.

[sline-dawg]

If you trapped the secondary--overflow-- drain, you would have to keep water in the trap always. If you want to go up there and add water every week or so, have a trap added and that will stop your " air leakage".....


But really, as stated before, it's so little to even worry about.

[acmech13]

you don't need the secondary drain. yet if its getting inspected its required. If its an issue after your inspection is complete. Have it closed off. your installers are installing a wet switch? The new drain pans come with a plug for there pan. something tells me your not getting that pan. its more expensive and not everyone wants to use it yet. but supposedly you can drive a truck onto it and it won't break. haven't tried that but have jumped on it really hard. make sure you are getting a wet switch even if its extra. turns your system off if your main drain ever backs up. you really don't want to use your back up drain it means somethings wrong in your attic.

[beenthere]

even though it may feel like a lot of air coming out the drain in the overall air flow capacity of a system it is nothing.

So if I drilled a 1/2" hole in the supply duct and didn't seal it, it would be ok because its just a little of the overall capacity?

[dash]

So if I drilled a 1/2" hole in the supply duct and didn't seal it, it would be ok because its just a little of the overall capacity?

Just one hole or more then one??

Will it be in a high static area or low ??



lol!!

[sline-dawg]

Terminate the drain in your living room and save the loss and you will know if the primary is clogged also... ;)

[beenthere]

Just one hole or more then one??

Will it be in a high static area or low ??



lol!!
LOL.

[dgreenb]

Lot's of good information so far, I think. I find it strange that there would be so much effort put forth to seal a leaky duct, or minimize airflow restrictions, or whatever, and yet have it by "fine" to have this drain line bleed out air conditioned air. I complained to the installer about the condensation forming on the cold drain pipe, so he insulated it. I guess that's a solution for the condensation problem.

As for air infiltrating the attic... I don't understand the relevance. The attic, ideally, is isolated from my air-conditioned space. The leak into the attic from the drain pipe will force air infiltration into the living space to re-supply the "lost" air into the return. This will come from any of the many, many other leaks in my 30 year old house.

So, I've got a float switch in the drain pan, which cuts off the AC. That's good. I wonder if I could shove a piece of sponge, or something similar, at the outside outlet to restrict the airflow, but allow water to capillary through. Or some other silly jerry-rig.

Also, there's a drain in the drain pan that's just capped off. Wouldn't it be better if this was the secondary drain? It'd be isolated from the airflow, and still warn me (by dripping visibly) if there's a problem.

Thanks alot guys!

[dash]

Lot's of good information so far, I think. I find it strange that there would be so much effort put forth to seal a leaky duct, or minimize airflow restrictions, or whatever, and yet have it by "fine" to have this drain line bleed out air conditioned air. I complained to the installer about the condensation forming on the cold drain pipe, so he insulated it. I guess that's a solution for the condensation problem.

As for air infiltrating the attic... I don't understand the relevance. The attic, ideally, is isolated from my air-conditioned space. The leak into the attic from the drain pipe will force air infiltration into the living space to re-supply the "lost" air into the return. This will come from any of the many, many other leaks in my 30 year old house.

So, I've got a float switch in the drain pan, which cuts off the AC. That's good. I wonder if I could shove a piece of sponge, or something similar, at the outside outlet to restrict the airflow, but allow water to capillary through. Or some other silly jerry-rig.

Also, there's a drain in the drain pan that's just capped off. Wouldn't it be better if this was the secondary drain? It'd be isolated from the airflow, and still warn me (by dripping visibly) if there's a problem.

Thanks alot guys!



A properly installed float swtch will prevent air leakage and warn you of a primary drain blockage by turning off the system.

[billygoat22]

E Z Trap makes a waterless trap that might work in this application.

I've purposely allowed air to flow out on some condensing furnaces to heat the pipe in subfreezing weather.

I've wondered that myself but never came up with a good solution that would also be maintenance free.

[acmech13]

i have ran a 3/4 pvc pipe as a heating duct. Its only job was to heat the condesate pump in an attic. i made a small duct box for the pump. kept the pump warm and heat taped the dain pipes.