Furnace ductwork modifications


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Old 09-05-18, 11:10 AM
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Furnace ductwork modifications

Received my Manual J and D heat calculations and need to make a few modifications.
Duct work is round metal 26 gauge. Furnace is under house in crawlspace.

Have to increase the start collar on the return air. Should I use an Airtite self adhesive with a few screws, or standard metal collar with tabs?

Ducting is held up by wires and will be replaced with metal strapping.

Will insulate all ducts with R6 duct sleeves and use mastic on all connections.

Registers and boots are resized from 2x14 to 4 x14, so thinking of using SpeediBoots.

A 10" end run terminates to three registers. One is 4", and two are 6". Should I use two wyes 10x4x6 and 6x6x6 , or 10x10x4 and 10x6x6?
 
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Old 09-05-18, 12:47 PM
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Start collar is your preference. As long as its sealed it makes no difference.

Never come off the end of a duct to a register. Put an end cap on and come back a foot or two and start a new takeoff for each register.
 
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Old 09-05-18, 02:14 PM
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Airman, Thanks for the advice.
 
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Old 09-08-18, 08:46 AM
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Ductwork modifications Schematic

Thought I would submit a schematic of the duct work design. Should I use a 90 degree elbow at each register, or two 45 degree elbows with a 6 to 8 inch transition between them?

Need to get 8 inches down to get under the floor joists.
 
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