How to tap existing HVAC duct

Old 05-13-20, 09:14 AM
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How to tap existing HVAC duct

I have a bunch of fish tanks in my basement and need to keep them at normal temperature (72 - 78) in hot NYC summer. I have central AC HVAC ducts running through my basement. How can I tap into my existing duct? Please refer to the mark up picture. I wish to add ducts/vents just over the fish tanks as indicated with red lines. I have zero HVAC knowledge but pretty good DIY skills working with PVC pipes. Can someone assist with below questions:

1. How to tap into existing duct? Can I make a hole anywhere to the nearest point? Also, If I were to get rid of the fish tank in the future I would like to be able to plug the hole back.
2. Can I use PVC or the flexible duct is advisable?
3. I considered using window AC but basement doesn't have bigger windows. Portable AC is an option but the problem is I have more tanks on the other side of the basement (not pictured here) as well so i would need two portable ACs.

My central AC is plenty powerful and we often feel its too strong so i think adding an outlet hopefully should be fine. Thanks in advance!
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Old 05-14-20, 06:54 PM
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You'd need to make sure your existing system can handle the additional load.
Don't use PVC. Use tin/steel like what is there.
You could use a piece of flex from the main to your new outlets.
You can use a saddle tee to tap the main or cut it and install a basic tee. Either way requires working with sharp steel. You could use several 4" tees over the tanks. The line from your new duct system to the main should be close to the same size as the main. You should also install a manual damper in the line to restrict the flow.

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