7" HVAC Duct Booster fan????

[Homerboy]

I want to install a duct booster fan in one of the runs in our house as there's just not enough air (hot or cold) getting to that room. I'm 90% sure the duct is 7" diameter, and I'm sitting here at work searching for a fan and can not find one. I see 4", 6" and 8" but 7" doesn't seem to exist?!!?

I know I could get two reducers to go down to 6" and back up, but I' prefer not to do that.

 

[Micrornd]

7" is an odd size.
If this is a single outlet register that needs boosted, have you considered a register booster fan?
They are readily available in the 120-160cfm size for some floor register sizes.

 

[Homerboy]

7" is an odd size.
If this is a single outlet register that needs boosted, have you considered a register booster fan?
They are readily available in the 120-160cfm size for some floor register sizes.

Yeah I gotta measure again, but I swear it's 7" (I'm at work right now)

the floor vent is a 2x12 (there's two of them) Nothing in that size is available. I was actually thinking about rigging some 50mm PC fans together
. It's a HORRIBLE duct run in an addition that was added on about 15 year ago. Way too many right angles and is the longest run in the house. I don't think a register fan could move enough air. Though I guess some is better than none.

 

[herm0016]

is it insulated flex duct or something?

if you can, do an 8 in fan and adaptors, this would probably work out pretty well as you will get a little larger fan.

or get a Mr. cool mini split in that room and close off the duct. haha.

also, is that the only register on the run? that is probably the main issue, as the flow area of a 2x 12 register is probably around 12 sq inches accounting for the grate and a 7 in duct is about 38 sq inches. without taking into account the bends.
It's a huge restriction, a fan will help, but a larger opening would probably help as much as a boost fan, and a larger opening and a fan would increase the flow a crazy amount. I hate that HVAC companies just throw stuff together and never do any flow calcs, or even consider the flow areas of the return vs the vents when they are installing a system.

 

[Homerboy]

is it insulated flex duct or something?

if you can, do an 8 in fan and adaptors, this would probably work out pretty well as you will get a little larger fan.

or get a Mr. cool mini split in that room and close off the duct. haha.

Not sure if I have room between the runs to go bigger to 8" versus smaller to 6" Maybe though... I still have to confirm it's 7"

I'd do the mini split, but that doesn't help with the lack of heat in the winter too

 

[herm0016]

I'd do the mini split, but that doesn't help with the lack of heat in the winter too

yes it does. mini splits heat and cool, they are heat pumps, they work both directions. I still have a hard time understanding how people believe that lie.

I will be installing a mr cool units in my new pole barn for heat mainly but the upside to it is Ill have AC when i want, and i can run it as a dehumidifier in the summer to keep all my tools nice and rust free.

example: https://hvacdirect.com/mrcool-diy-1...p-with-wireless-enabled-smart-controller.html

we installed a 3 head mitsubishi hyperheat system in our previous house for additional heat when the hot water base board could not keep up and for AC in the summer in the bedrooms. worked perfectly and kept us warm even when the outside temp was -20.