Should I change the 6'' duct pipe to 8 " in my application?

[Dmitry]

It's not exactly a furnace question, but I figured it's a lot of experts on this forum about the subject.
I'm transferring heat from my basement wood stove to the main level through one already existing floor register connected to 5 feet of 6-inch duct. I decided to use a 4 ft of 8 inches duct above the stove to suck the heat. I'll use an inline 442 cfm fan to move the air.
Should I change the existing 8-inch pipe, or it will be no difference since register connection is still 6 inch.
Any advice appriciated.

 

[brenndatomu]

Changing everything to 8" would almost double your flow...doing as you suggest however will only increase it slightly.

 

[Dmitry]

Changing everything to 8" would almost double your flow...doing as you suggest however will only increase it slightly.

I’ll leave the 6 in place . Not sure how successful heat transfer will be. Not ready to tackle the register yet.

 

[Dmitry]

I’ll leave the 6 in place . Not sure how successful heat transfer will be. Not ready to tackle the register yet.

Changing everything to 8" would almost double your flow...doing as you suggest however will only increase it slightly.

Never thought there is such big increase in airflow going from 6 to 8. Is that really noticeable subjectively?

 

[brenndatomu]

Really hard to say if it would be noticeable for that application or not.
But yes, 6" is 28.26 sq in, 8" is 50.24 sq in.
flow pretty much doubles each time you go up a pipe size 4-6-8-10-12...actually, I just looked up an airflow chart...its more than double from 6"-8"!
(broken link removed to https://hvacdirect.com/hvac/pdf/Field_duct-sizing-chart.pdf)