To Vent or Not to Vent

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Jgrden

Jgrden

Member
Joined
Mar 27, 2009
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6,287
Location
hOUSTON, Texas
My wife and I debate the wisdom of shutting off central air heating vents to certain areas of our house. I say the system needs to breath and the vents should remain open to allow the whole house to adjust to a level temperature. Wife says, no it concentrates the air flow to specific parts of the house that needs heat, fast.
What do you think?
 
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Talk with your heating and cooling specialist. A home should be balanced, meaning that it should heat and cool evenly. Closing off vents and or rooms will cause an inbalance.
 
Toni said:
I have been asking my dh the same question but of coarse it is in regards to AIR CONDITIONING:eek:....LOL
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Be careful Toni.

When you close vents it restricts air flow and you could cause icing of the air exchange coils. If they ice up, the air stops moving all together and the house gets hot. You then have to shut the system down and let the coils thaw and then turn it back on. Not worth the extra coolness for the brief time. DAMHIKT

For hot air, It shouldn't matter as much, but the air restriction would obviously still occur to a degree.
 
My HVAC guy says unless your system has dampeners in the plenum then leave them open. The way he explained it to me was by shutting them it causes something like a back current in the ductworks that reduces the efficiency of the airflow making the blower work harder and recucing overall efficiency. I said huh and he said leave them open.
 
Dont know if its correct or not but this is what we do.

Summer - Close all but 1 vent on the first floor to push the cold air upstairs. It has been over 110 maybe 120 in the bed room on days we left and forgot to set the AC.
Winter - Open all vents.
Thermostat is in the center of the first floor.
We dont have any trees to block the sun or the wind.
Not that is matters but just thought I would mention it.
 
lazyguy said:
My HVAC guy says unless your system has dampeners in the plenum then leave them open. The way he explained it to me was by shutting them it causes something like a back current in the ductworks that reduces the efficiency of the airflow making the blower work harder and recucing overall efficiency. I said huh and he said leave them open.
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That makes sense...although to throw something else in the mix would be how many cold air returns are there in the house. If there are enough, then I don't think a back current could happen.
 
I learned a long time ago to always keep the vent tightly CLOSED.....I'm refering to the one right below my nose!
 
As a professional builder who knows a LOT about building science and how a home works as a system, my advice is DO NOT close the vents. For one, your HVAC system was designed to have all the vents open and closing a lot of vents will cause more back pressure on the system. Probably not an issue but it will not be working as designed. From a building science stand point, you need to keep all of the rooms conditioned to help in moisture removal. In your area, you are in a hot and humid climate. Even in the winter time, the humidity outside is higher than it is inside most of the time. Nature seeks a balance and moisture is constantly coming through your walls to the inside, even with the best of housewraps. Part of the job of an HVAC system is to remove moisture. Closing the vents will allow the air in those rooms to "stagnate and not have the proper air changes and will result in higher moisture levels inside your home. One thing interior of homes do not do well with...moisture.
 
I agree completely with what Curtis has stated in his reply.

I was advised like this ... IF the room you have closed off has a return air vent, then that air will not be treated as it goes back into the 'system'. If that air is hot in the summer it will cause the AC to work harder, and the same room air in the cold of winter will dilute the warm air and thus make the heater work harder. Both will add $$$ to your utility bills.

Leave the vents open and unblocked by curtains, etc. Proper insulation will do far more to lower costs and increase the comfort in your home.

It may look unusual from the outside and block your clear view in and/or out, but just a simple layer of clear plastic bubble wrap on the glass of the window will greatly add to the prevention of loss of AC or heat. Large bubbles or small, either one does wonders.

Use clean bubble wrap and cut it to fit edge to edge on the glass, it is important to clean the glass as well. Lightly and evenly mist the glass with plain water and apply the FLAT side (yep, there is a flat side and a bubble side) of the bubble wrap to the glass. Do not trap any air between the glass and the bubble wrap. Wipe off any excess water from the sill. The bubble wrap will stay in place for years unless someone disturbs it. Try it for yourself and see if you like the results.

BTW, the bubble wrap is safer to use on thermal pane windows and does not seem to build up pressure from reflected heat between the glass panes like reflective foil window treatment has a tendency to do. :eek:
 
Mold . . .

No circulation in a room in a humid area = mold . . .

It's slow at first, but once it gets started it "mushrooms" . . . forgive the pun . . .

Then it spreads . . .

Steve


Jgrden said:
My wife and I debate the wisdom of shutting off central air heating vents to certain areas of our house. I say the system needs to breath and the vents should remain open to allow the whole house to adjust to a level temperature. Wife says, no it concentrates the air flow to specific parts of the house that needs heat, fast.
What do you think?
Click to expand...
 
When we went through HVAC school, we were instructed to never close individual vents in residential work. If the system was correctly installed, it was in a balanced state and the air flow was needed to release any back pressure on the air handler. Once vents start to be closed, pressure builds up in the ductwork allowing the heat exchanger to over heat in heat mode shorting the life expectancy of the furnace. In chiller mode, the evaporator will possibly freeze over causing the compressor to overheat and be damaged. On top of all that, add what Curtis just said. Just leave the vents open and regularly change the filter.
Charles
 
Conditioning with air can provide us with delightful opportunities. A sudden rush in any direction can cause premature reactions Tony something to avoid if harmony is important.

Careful manipulation of vents will acheive only if the balance is maintained by adjustment now and when restored at a later date. I have whole of house heating and four reverse cycle Air Cons for the most used rooms so immediate relief can be had in those difficult times. Critical
positioning of the Thermostat provides greater control over favoured places.

The last two words I use are sorry darling to SWMBO. This after 55 1/2 yrs of marriage proves also a wonderful investment.

Kind regards to you in your time of need with heat we are in the opposite phase its 90 plus inside now.

Peter.
 
Ok, I've got a stupid question:
If vents in residential construction are designed to be left open all the time,
why install operable vents?!?
Yes, I understand the air-flow posts, I guess this is more a follow-on to the ecomonics of the original construction when typical HVAC is installed.
 
Keep thammmmm open....Oooopss I meant keep them closed..........Now either open or closed.. Keep thaammmmm closed.I don't know which way is up any longer...
I knew, that he knew, that I knew, that he knew.. who's on first!!! what's on second!!!why's on third!!! now wait, who's on first? I told you Who's on first. I think I'll keep that thing under my nose closed."STOP IT ALLREADY":)
 
Papo said:
Keep thammmmm open....Oooopss I meant keep them closed..........Now either open or closed.. Keep thaammmmm closed.I don't know which way is up any longer...
I knew, that he knew, that I knew, that he knew.. who's on first!!! what's on second!!!why's on third!!! now wait, who's on first? I told you Who's on first. I think I'll keep that thing under my nose closed."STOP IT ALLREADY":)
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How much wood can a woodchuck, chuck, if a woodchuck could chuck wood.
A wood chuck, would chuck as much wood as a woodchuck could chuck, if a woodchuck could chuck would. :question:
 
Jgrden said:
Papo said:
Keep thammmmm open....Oooopss I meant keep them closed..........Now either open or closed.. Keep thaammmmm closed.I don't know which way is up any longer...
I knew, that he knew, that I knew, that he knew.. who's on first!!! what's on second!!!why's on third!!! now wait, who's on first? I told you Who's on first. I think I'll keep that thing under my nose closed."STOP IT ALLREADY":)
Click to expand...
How much wood can a woodchuck, chuck, if a woodchuck could chuck wood.
A wood chuck, would chuck as much wood as a woodchuck could chuck, if a woodchuck could chuck would. :question:
Click to expand...
According to GICO, it looks like about ten or so sticks!:biggrin::wink:
Charles
 
I have done a lot of home remodeling and repair in the past. I will just keep it simple and say I agree with Curtis. Shutting down a portion of your house has an effect something like leaving a car parked in a garage. or finding a house that has been setting empty for a while. Nobody has been there but they are not in the best of shape, strange smells and that sort of thing. They mean something and none of it is good. In short a house has to breath and the ventilation system weather it is the heat or the AC is part of that ability to breath. I remember an Aunt and Uncle that shut up the entire second floor of their farm house after their children grew up and moved out. It had a musty smell to it that I don't think they could ever get rid of. wall board started peeling off the wall also. That may be an extreme case but at least gives you an idea what starts happening in the no seeum places.
 
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