# Damage to duct work and HVAC can occur with shut-off vents?

**URL:** <https://boards.straightdope.com/t/damage-to-duct-work-and-hvac-can-occur-with-shut-off-vents/986248>\
**Category:** Factual Questions\
**Created:** [June 28, 2023, 5:48pm UTC](https://boards.straightdope.com/t/damage-to-duct-work-and-hvac-can-occur-with-shut-off-vents/986248 "2023-06-28T17:48:18Z")\
**Posts on this page:** 3\
**Page:** 2

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**Author:** ![gnarator](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gnarator/32/8266_2.png) [@gnarator](https://boards.straightdope.com/u/gnarator)\
**Post date:** [June 30, 2023, 9:11pm UTC](https://boards.straightdope.com/t/damage-to-duct-work-and-hvac-can-occur-with-shut-off-vents/986248/21 "2023-06-30T21:11:40Z")

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>
> Learn all about how zoned HVAC works, plus how this type of system can improve your energy savings and comfort.

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**Author:** ![Snipe70e](https://avatars.discourse-cdn.com/v4/letter/s/51bf81/32.png) [@Snipe70e](https://boards.straightdope.com/u/Snipe70e)\
**Post date:** [June 30, 2023, 10:16pm UTC](https://boards.straightdope.com/t/damage-to-duct-work-and-hvac-can-occur-with-shut-off-vents/986248/22 "2023-06-30T22:16:26Z")

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More important to get the return air from the hot space. The house that sold I had made some changes. Originally the 2nd floor return register was near the floor. I added a second register up high near the ceiling. In the summer I would open the high register and close the low register. I would set the fan control on the thermostat to on rather than auto. I also assed an inline fan on the return air duct from 2nd floor. And I would block the 1st floor return register by about 30%. I also throttled back the register near the stat Before doing this the 2nd floor would be 10 degrees hotter than 1st flood. Not good for sleeping at night. After I made the changes 2nd floor was about 2 degrees cooler than 1st floor.

But I did check to besure there was proper air flow across the A coil of the AC.

Now my new house I need to keep everything open and not add any resistance. My ducts are under sized. 15 inch return and supply going to the A coil. But for the size of the unit the ducts should be 20 inch.

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**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\
**Post date:** [June 30, 2023, 10:35pm UTC](https://boards.straightdope.com/t/damage-to-duct-work-and-hvac-can-occur-with-shut-off-vents/986248/23 "2023-06-30T22:35:57Z")

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You need a remote thermostat.  
One made a HUGE difference in the comfort level of our house.

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