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New home HVAC return duct just added...is this proper?

Posted by stowed (My Page) on
Tue, Oct 30, 12 at 9:28

Hi,

I am new to this forum and this is my first post.

We just completed a new house and moved in last week. We have a pretty high end HVAC system with radiant floor heat (Uponor) for 1st and 2nd floor, Bryant air handler supporting two zones (1st and 2nd floor) and a RenewAire air-to-air exchanger. We noticed that we were not getting much flow from the vents with the air handler going and eventually the unit stopped and kicked off a "pressure" error message.

The HVAC guys came back in and fixed the system (which seems to be working better) but did it in an odd way IMHO. They added a return vent right a the main duct as it enters the air handler just above the filters. This is in the basement which is 5' away from the furnace. Is this proper?

I only noticed because as the system was running I noticed the basement door inside the house getting sucked closed (and slamming) a couple of times. When I went to explore I could feel the pressure on the door when opening it. As I put my hand up to the new return vent on the side of the duct it creates a very strong suction pressure.

I have a few questions and concerns. First, is this a proper way to fix this problem? I'm obviously more than a little annoyed that this seems to be a work-around for an improperly designed system in a new house. Additionally, I am not thrilled with the unit sucking air from the basement and not the house above introducing the potential for other basement gasses including furnace fumes into the house. Finally, it seems like this violates one of the advantages of the air-to-air exchanger which injects the clean outdoor air into the 1st and 2nd floor when most of the new air comes into this via the new duct vent in the basement where no fresh air is circulated.

Any thought or comments are much appreciated.


Follow-Up Postings:

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RE: New home HVAC return duct just added...is this proper?

Do you have a gas hot water heater with a vented natural draft near the furnace? If yes then adding this return is dangerous. It could suck fumes from the hot water heater vent.

It sounds like the return vent is undersized. The vent is causing negative pressure in the basement. In general it is not a good situation.


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RE: New home HVAC return duct just added...is this proper?

I doubt this is an issue for fresh air. There is a limit to how much fresh air you can bring in and it is much lower than the output of the air handler (most likely). So you have to use some recirculated air.

Second, if there is something in your basement air that you don't want to breathe, then you have a problem independent of the setup.

I am guessing the basement is unfinished?

Air intakes are at the air handler all the time - I have a new house that is set up that way. So don't worry about that aspect.

When I finished my basement, I found that I can meet all of my HVAC needs by just having a return there. It circulates the air enough to regulate humidity. I suspect the basement will get a little cold in the winter and I can increase the airflow but in the summer, closing the vents made the area perfectly comfortable.

Hey - if it makes you feel better, I have a newer house with an expensive zoned system and they had to install an extra return in my master because of door slamming. When I have one zone calling for stage 2, there is more airflow than is comfortable. I have been building work arounds for the last 3 years. What I can say is that my bills are extremely low and after the work arounds, it is near perfect.


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