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Guncho · 08-31-2010, 09:05 AM

We had a new central air conditioner and furnace replaced the other day and the installer told me to do something I've never heard before. He said you should always leave all the vents open as it's a system or something like that. Normally in the summer I would close all the vents in the basement as it's cool down there anyway.

What do you guys think?

In mind, it's as simple as if you weren't supposed to close the vents ever, why are they adjustable?

Thanks,
Chris

handyguys · 08-31-2010, 10:45 AM

They are adjustable for setting the initial balance of the system. After that they shouldnt be touched. Sometimes this is done with inline dampers. The goal is to have the same return and outflow. If you don't then the system will not work as designed.

Guncho · 08-31-2010, 10:53 AM

Quote:

Originally Posted by handyguys

They are adjustable for setting the initial balance of the system. After that they shouldnt be touched. Sometimes this is done with inline dampers. The goal is to have the same return and outflow. If you don't then the system will not work as designed.

I'm talking about the vents where the cold air comes out of. Wouldn't you want to adjust these as the seasons change?

handyguys · 08-31-2010, 11:00 AM

no - those end vents push cold (or warm) air into the room. That air needs somewhere to go, hence the corresponding return vents. If you close the end vents and the returns are sucking air from the room (creating a vacuum sort of) and making the system work harder to provide cool (or warm) air to the other rooms.

If you want to save on cooling or heating costs you would do much better by adjusting the thermostat a couple degrees warmer in the summer or cooler in the winter.

Guncho · 08-31-2010, 11:51 AM

Each room doesn't have a return vent. There's like 1 or 2 on the main floor and an intake on the furnace itself.

handyguys · 08-31-2010, 11:54 AM

That makes no difference. return should equal supply. If you decrease supply you can starve the system. The professional gave you the correct advice. Its up to you if you want to listen to it.

Guncho · 08-31-2010, 12:02 PM

I'm sorry if I just don't get this but why would closing an outtake vent decrease supply. Wouldn't it just be like that room doesn't exist to the system and more cold air would go to the vents that were open?

If you're not supposed to open and close these outtake vents, why is there controls on them to open and close them?

**inspectorD** · 08-31-2010, 02:18 PM

Ok Guncho, HVAC 101.

You need the same total input, as you do output.

3 bags O stuff in , 3 bags O stuff out. Your home should be a closed "balanced" system or it will work to hard tryin to push 1 bag out if it becomes unballanced. The adjustable vents are there to help fine tune the balance, you do not really touch those after they are set or it gets kind of "backed up" so to speak. Like if you where to cinch up your belt after eating a large pizza yourself.
And basements need airconditioning in the summer most of all, it keeps the humidity lower and helps the A/C unit to work better. Your actually making it work really hard when you close those vents in the summer to the basement.
That's why the pro's get the $$.They go to lots of school to figure these things out.
Hope the analogies helped.

Guncho · 08-31-2010, 02:25 PM

Ok I'm hearing you know. My only concern now is the installer didn't "balance" the system. He opened one vent to show my wife what he was talking about but didn't touch the others. I guess I will just open all the vents.

Another question. I read somewhere that I should have the fan set to on and not auto in the summer. Is that true?

MSU Fan · 09-02-2010, 11:55 AM

What about the cold air supply in the bathroom? My bathroom does not have a return. ???