An AC Return & Vent no longer needed

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Wes

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This past summer we had central air installed.

It has one zone/thermostat.

The main area of the house as several vents and one main return. An unfinished bonus room over the garage has 2 vents and one return. The return and vents for that room are not branches, they connect directly to the air handler.

The bonus room was going to be finished this past fall but has to get delayed for a year or two.

What should I do to temporarily disconnect the 1 return and vents from the unfinished bonus room?

thanks
Wes
 

Jadnashua

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I'd consider placing dampers near where they branch off from the air handler. An alternative would be to take that segment out and put a plate over it.

Note, if the air handler is set up properly, blocking off a branch may mean the fan speed should be changed or you may end up with high back pressure and shorten the life of the motor and excessive noise from the air moving too fast.
 

Wes

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No dampers

The two supplies don't have dampers right now.

If I install some dampers can I just put a damper on the return, also?

thanks
Wes
 

Jadnashua

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an air handler has a range of cu ft/m for any cooling coil. If by closing off the duct you are still within range, good. You can use dampers on both.
 

BurleyMike

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By closing that room off you could end up reducing the airflow too much. If your evaporator turns to a block of ice then you know you don't have enough airflow. The system was sized with the load from that room. Taking that room out of service will mean you have an oversized system.

Setting the motor to a lower speed will solve the too much CFM problem but not help with the A/C system being oversized. If your air handler has a TXV you may be ok as a TXV can adjust the amount of refrigerant the evaporator gets based on the load.

Best thing to do is keep an eye on your evaporator to make sure it does not grow ice.
 

Wes

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Cool

The system was "just big enough", with a reasonable margin, to handle all the rooms including the addition. I don't have the exact numbers but I'm guessing it will be ok.

Thanks for the advice. I'll give it a try and keep an eye out.

thanks
Wes
 

Wes

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Uh oh...

Ok, so how do I install dampers?

It's just insulated flex pipe from the air handler out to the vents. I looked up dampers on a plumbing supply site and obviously it's just the damper. Do I need to install some sheet metal pipe and put the damper in it?

thanks again!
 

Jadnashua

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If they're flex and not solid, I'd consider just disconnecting them and putting a cap on the supply end. The dampers I'm familiar with are designed to be installed in a section of slide pipe. It may not be hard to install a section long enough to do this, but then you'd have the ducts off and a cap would work and not leak a little like any common damper would.
 

Wes

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Cap

Yes, they're flex.

I'll take a look at getting some end caps and popping them on.

thanks.
 
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