Wide open return in basement - seal it?

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  #1  
Old 03-25-08, 07:35 PM
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Wide open return in basement - seal it?

Hello! I have no experience in HVAC and was curious about a wide open return in my basement.

I have a ranch style home that was built in the 70's. The HVAC system's main return duct in the basement is wide open at the end near the wall. It bothers me and I have this urge to seal it. It looks like the installers forgot to close it up. However, I have 10 registers and 4 returns (not including the open "return" in the basement).

Does it make sense for me to seal the wide open end of the main return duct in the basement? Is it dangerous ? From some of the posts I've read (not too many), I'm wondering if I should leave it open because the 4 returns would really have to be pulling in a lot of air to compensate for the total amount of registers, right? None of the 4 small (normal) returns are in the basement.

Anyone have any thoughts or suggestions?

Thanks in advance for any advice...

Chris
 
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Old 03-26-08, 06:04 AM
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If you are supplying conditioned air down there then leave it. You will have a nice place down there with it. Closing it up could cause low flow issues across the coil/heat exchanger.
 
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Old 03-26-08, 11:26 AM
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I would leave it open. Your unit also probably supplies heat and by leaving that return open, it will help to keep your basement temp balanced along with circulated air. That is important for basement air(mildew, stale, humidity). If the looks bothers you, put a grill on it.
 
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Old 03-26-08, 11:45 AM
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Thanks

Thanks for the comments. Based on what you said, I'll leave it open. Thanks...
 
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Old 03-26-08, 03:45 PM
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The one question nobody has asked is, do you have adequate return air flow from upstairs with the duct open?
 
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Old 03-26-08, 07:38 PM
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oneofamill,

RE: adequate airflow upstairs with the duct open - What should I do to answer that question? I mentioned below that I have 10 registers and 4 returns. There is no basement door, so I'd imagine that there would be free air flow to the basement would you agree? And is that a situation you'd want? Or is that a negative?

Alternatively, if I had a shut door to the basement, the airflow down to there would be restricted, correct? What could happen in that situation? It would cause the air on the top floor to go through (mostly) the returns on the top floor, correct? I'm thinking that the basement door (if I had one and it was shut) might collect dust around it (assuming it wasn't 100% sealed). And the air in the basement would... what would happen with the air in the basement?

To make sure I got it straight - the register is where the air comes out of the ducts into the house and the returns are where the air in the house goes back into the ducts, correct?

Chris

P.S. Sorry I wrote so much there, but I actually find this kind of interesting.
 
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Old 03-27-08, 09:06 AM
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You said you have 4 returns + the basement return AND no basement door. You have plenty of return air. Even if you close off the basement return and have NO basement door, the air would still be pulled back into the system. I think it is a toss-up. I would just put a grill cover on it. I assume when the system is on, you can feel a "pull" through it?
 
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Old 03-27-08, 09:18 AM
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Wink

What did I miss?? Do you have any registers down there in the basement with that return?????
 
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Old 03-27-08, 05:46 PM
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rpatzer,

RE: "pull" through it when system is on - yes. you can definitely feel a pull through it.

Ed Imeduc,

RE: any registers in the basement with the return - Well, sort of. Half of the basement is finished off and half isn't. You could say it is divided by the steps down to the basement. The half that isn't finished has a washer/dryer, water heater, and the HVAC unit. The unfinished side has the open duct/return. The steps to the basement lead right in to the unfinished side.

On the right of the basement steps, you can get to the finished side through a door which is almost always closed. On that finished side, there are two circular registers coming off of the ceiling (blowing air down into the room). Oh - so wait, that means I have 12 registers, not 10. Sorry about that. I forget about those two all the time. Anyway, there are no returns on the finished side of the basement.

So, that's the scoop. 12 registers, 10 upstairs 2 downstairs in closed door room not on same side as open duct. 4 returns, all upstairs, and then the wide open duct in the basement...

Chris
 
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Old 03-28-08, 07:59 AM
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OK- the picture is getting larger. It sounds like the supply and return are in different rooms, with a possibly closed door between. I would leave the return operational. It makes for better circulated air in the basement.
But I see another issue: If your supply in the basement is in the finished side with the door mostly closed, and you leave supply open, then I would either put a return in that room or leave the door open so the air can return to HVAC. It sounds like your supply and return in the basement is in 2 different rooms with a door mostly closed. I would keep everything free to blow/return as much as possible for the reasons I stated earlier. You may not heat that area, but I would always keep the return operational, being a basement.
 
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Old 03-29-08, 05:19 AM
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rpatzer,

Thanks for the response. This is good information...

OK - I feel real dumb about not mentioning this, but a friend pointed it out last night that my returns are the same size as my registers, a lot smaller than the ones he has in his house. So those 4 returns are about 12" x 7" each. Those are kinda small compared to the huge ones I've seen in some houses. I suppose this only furthers the notion that I should be leaving that big duct open, right?

Chris
 
  #12  
Old 03-29-08, 09:28 AM
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I would leave it as it is. We have just the one 18X18 return. Yours seems to be calculated out with the big one inline. Use it as is.
 
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Old 03-29-08, 01:35 PM
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Wink

Could cut about another 1" off that door down there in the basement. Also the round registers are good for the AC . But dont blow the hot air down to good when on heat.
 
  #14  
Old 04-03-08, 03:32 PM
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After reading this thread my impression is that the block end was removed because your furnace was starved for air. I'd leave it as is.
 
 

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