return question... - http://www.hvacmechanic.com/ Forums
Original message
| homey6660
 |  "return question..."
, posted Mon 9 Jun 10:41  
I just had the AC installed and I went with two returns--one on each level of my 1600 sq ft house. RIght now, the ducts are still exposed b/c the contractor is working with me to fine tune the install based on how it's been operating. The first floor gets cool very quickly and easily. The return is pulling a lot of air, based on my hold-a-papertowel-in-the-return-and-watch-it-flutter test. The return upstairs pulls less so and it is much warmer upstairs (split system wasn't doable, so I have to figure out how to make do with what I have). Now, as far as I know, there are three reasons for it being warmer upstairs...
1. it's further from the source, so it's inevitably going to be pushing less cool air to the far reaches of the duct line.
2. b/c the ducts are exposed and the registers are not on, a lot of the air is blowing out the lower level--more than it would if there were registers.
3. size of the returns (and this is my real question). I had a 2nd contractor come in to take a look and he suggested that the ducting where it connects with the blower should be narrower for the 1st floor return than it is for the 2nd floor return (right now, they're both 10 inches). His rationale is that if the return is going to pull the same amount of air, if you restrict the one on the 1st floor, it will allow more air to be pulled from the 2nd floor. Do you guys agree?
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Replies:
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| geo fan
| "Re(1):return question..." , posted Wed 11 Jun 21:32
you have a 2300square foot house and it sounds like everything is still open enough zone the system with some automatic dampers pull t stat wires to both floors and install a dump trunk to the return depending on your area its fairly reasonable im in ct in one of the most expensive areas greenwich in one of the most expensive companys and we charge like3000 but other then that the first guy was right
ctd2b
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| yuri
| "Re(1):return question..." , posted Mon 9 Jun 19:50
No. That is why you have registers and dampers to BALANCE the system. Just did a 2300 sq ft house today and used a velometer to setup the airflow to the different vents. You throttle back the main floor and the airhandler pushes more upstairs. We don't throttle with return air duct sizing.
Yuri
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