air comig down air return

[Bob E.]

Have been working this problem for 11 months - new construction. On cold, windy days, very cold air comes down one of the 3 air returns; same one all the time - other 2 work fine. THis happens when the sytem is inactive. It isn't residual air after shutting down. It will come down the air return as long as the wind blows outside. My HVAC vendor has tried various fixes, mostly minor taping of ducts connecting to air return - applying mastic in the air return box - etc., but seems stumped in how to find, and fix the actual problem. We have 3 air returns, and one large, 4 inch, Honeywell Media filter in the air handler in the attic. Our HVAC company has temporarily added another filter to the air return in question. This seems to have caused the master bedroom, which is just beyond that air return to now be 3 - 4 degrees cooler than before. Our home inspector suggested adding a damper to the air return in question. I sure hope someone has experienced this problem and found solutions, or someone that has ideas on how to actually fix this.

Thanks for any inputs and ideas.

Bob E.

[HayZee518]

air returns are supposed to bring cool air back to the heat exchanger to be reheated, then blown back into the ductwork. are we talking about the same thing or are you referring to the chimney?

[Bob E.]

It isn't returning air when this problem occurs. The system is inactive - blower motor off. Very cold air just falls from the air return duct "down" into our home; esp. on cold windy days. Am trying to find possible sources of this problem. We have 2 other air returns and they aren't affected - meaning no cold air comes down them when the other does have a problem. When operating as heat, the system works fine - just when the system is off, thye cold air comes down.

Thanks for the feedback, and sure would appreciate any ideas folks may have.

[Speedbump]

The only way cold outside air can get into the system has got to be through a leak in the pipes or the air handler itself. What kind of system do you have? What are the ducts made of?

[Bob E.]

The system is all Carrier (installed late 2013). Ducts are in the attic and are the flexible type with a duct within a duct. The company that installed the system has said they have looked at it multiple times, which they have, but can't find the source. How could I test the pipes and air handler as mentioned Speedbump? Thank you for responding.

[Speedbump]

First of all, I'm not an HVAC guy, so I'm just looking at this problem with common sense. If the ducts are in the attic, I assume it's about as warm in the attic as it is outdoors. So if the air handler is in the attic also, the cold air has to be getting into either the ducts or the air handler from the attic. There has to be a loose joint, a tear through both layers of the duct or the air handler plenum (for a lack of the correct term) is open somewhere somehow allowing that air into the duct work. Check to see if the place the cold air comes into the home has the shortest duct. That would make sense if it's coming in from the air handler. If not, I would assume a tear in the duct obviously on the side that can't easily be seen.

The installers should be crawling in your attic until they find the problem. I wouldn't let them off easily.

[Bob E.]

Thanks Speedbump - have a year-end meeting with the builder next Tuesday and will present the air is coming in through either the duct (tears or bad connections) in question, or maybe where that duct is attached to the air handler.

[Speedbump]

Good luck, hopefully he will get the problem resolved. I have friends who move all the time, always new homes and they give the builder fits about little hen peck things, but the builder always addresses them quickly. They don't want any bad advertising.

[KDGrayson]

There is only 1 way outdoor air is blowing out your return air, that is a badly cracked heat exchanger, the exhaust flue can get a drat if the flue is not terminated higher than anything within 3 ft of it, I forget how much higher but its easy to Google that. still this could never get into the return air without the heat exchanger being compromised, the fixes sound dumb quite frankly, you might have to go look at this return yourself as it is not adding up at all.

[Bob E.]

Thanks KDGrayson. I appreciate the feedback.

There is only 1 way outdoor air is blowing out your return air, that is a badly cracked heat exchanger, the exhaust flue can get a drat if the flue is not terminated higher than anything within 3 ft of it, I forget how much higher but its easy to Google that. still this could never get into the return air without the heat exchanger being compromised, the fixes sound dumb quite frankly, you might have to go look at this return yourself as it is not adding up at all.

Thanks very much for your feedback and will keep working this with our builder and HVAC company.

[Jarome Iginla]

I suspect that the compressor or condenser is not running or there's a refrigerant problem or the thermostat control is not switched to cool mode. Heating and cooling work may require repairing or installing plumbing to supply oil or natural gas to heating equipment.

[HayZee518]

Jerome, your posting doesn't make sense in addressing the op's problem. Sure! It can be any one of yours!

[mrcaptainbob]

At the time the one of three cold air vents is giving off that cold air, check the other two for a draft back up. I'm wondering if it could be a conve3ction issue. The warmer air near the two vents moving to the attic, cooling off and falling back to that third vent. The room that third vent is in may be cooler than the other two. Put another way, the other two vent's rooms are warmer at the floor level and naturally want to rise...... Check for the air flow.

[Allen Smith]

Your system might have some leak in the pipes or some crack in the heat exchanger.But I'm not sure what might be the possible problem as you said it has been checked several times.You need to contact your builder about what kind of installation is this and then can give a call to any local AC repair company to get a guy there and get the system checked.The important thing is to know the cause of the problem and try to get someone who is really expert HVAC guy.