Help me get my ducts in a row
September 17, 2015 1:36 PM   Subscribe

Great A/C keeps 80% of house comfortable, turns basement into an arctic wind tunnel.

We just moved into a new house (DC area). Older house, but with brand new HVAC and A/C, and Nest thermostat. It's a split level house. While the machinery/thermostat combo do an ok job of keeping the middle and upper floors close to the desired temp, the basement is always a deep freezer. This is a problem because our guest bedroom is located down there, and the air duct (which comes directly from the fan in the utility room next door, thus with strong force) blows ice cold air out at an alarming rate through a ceiling register. We've closed the doors on the register in the bedroom, but it hasn't been enough to keep the cold air from blasting out. Problem is, if we turn the A/C down so our downstairs bedroom guests are comfortable, the temp upstairs rises to uncomfortable levels. This problem will go away soon as fall arrives, but will undoubtedly plague us again next summer.

So, it's both a question of air temperature and the force of the air coming out of the register, which is enough to leave anyone sleeping in that room with Sahara eyes in the morning. Looking for suggestions for any more mechanically-inclined MeFites on how to address.
posted by GorgeousPorridge to Home & Garden (6 answers total)
In addition to closing the vent, consider getting a magnetic vent cover that will go directly over the vent.

If you want to spend more money, you wish to consider separating that duct entirely and running it off its own condenser, or alternatively installing a mini-split system just for the basement.
posted by Karaage at 2:26 PM on September 17, 2015

This sounds like a crappily designed or set up system. I'd call out an HVAC company to come take a look and rebalance it. On a properly set up system that much flow and pressure wouldn't be wasted on a vent right next to the blower.

Just because it cools the rest of the house decently doesn't mean it's doing it efficiently. It's probably unbalanced all over the place.
posted by emptythought at 2:47 PM on September 17, 2015 [1 favorite]

Or, right as i hit submit, that wasn't originally a bedroom and that register was either added by a homeowner or the handyman with no regards to the rest of the system, causing this problem. Either way, you need a pro to look at it.
posted by emptythought at 2:48 PM on September 17, 2015

Sounds like you need a damper adjusted or, more likely, installed in the duct to control the airflow to that room. If you are getting too much airflow with the register closed, then you need to damper that duct way down. And it wouldn't be a bad idea to have someone look at balance for the whole system while they are it.
posted by ssg at 3:19 PM on September 17, 2015 [3 favorites]

Our hvac system has baffles that control the flow to each floor. They are on the main duct trunks in the basement. If you have these, adjust them so the upper floors are on full blast and the basement is nearly closed. On our system they are metal handles on the side of the duct; parallel to the duct means open and perpendicular to it means closed. It makes a big difference in our house.
posted by telepanda at 3:59 PM on September 17, 2015

I concur, a baffle INSIDE the duct feeding that room is needed. I had a similar situation in a room that was two feet from the air handling unit, there was no way the control on the vent cover would keep all that cold air out... Installing a well sealing baffle in the duct solved the problem.
posted by HuronBob at 8:23 PM on September 17, 2015

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