Practical question regarding ductwork

[beenthere]

Thanks again for the words of professional wisdom. I am wondering if I can step down to 24" round because that is the largest diameter available in flex pipe, everything else above is custom sizes. Also is there a direct equal relationship between sq. area of round duct and rectangular one?

I know that prices are not permitted here but can you at least give me an idea on the difference between all these materials, so I know where to spend most of my time.

24" will work. You still want it to make 2 90° bends. Velocity is up a bit, but should be ok.

Best to just call around and get the actual prices to know what the difference will be.

[54regcab]

Have you considered using multiple smaller fans, one for each room?

[ProperVenting]

Have you considered using multiple smaller fans, one for each room?

Yeep, please check it out here

[54regcab]

If your objective is to save on AC costs during mild weather you have a VERY long payback time...

[Jesjen829]

Because I do not believe in this solution as it implies that there is 1 (One!!) central location from where it is pulling all air. They are not powerful enuf and what happens when all bedrooms doors are closed. Where it will suck the air from??!!

I have a whole house fan and it keeps the first and second floor pretty comfortable when outside temps are at 85 degrees. Above that ac goes on. You can either trim your doors or put back to back ra grills above the doors. This will be alot cheaper and easier than ducting each room imo.

[ProperVenting]

Hmm..what fan are you talking about? What about noise level?

[Jesjen829]

I don't know the brand it was here when I bought the house. Its noisy as hell when I start it up but after that its not too bad. My electric bill in the summer is around $75. I can get used to a lil noise. I can't get used to 200 electric bills. Not until I win the powerball lottery

[jtrammel]

With the price of sheet metal and fab work, metal prefab duct, flex duct, duct board and/or canvas connectors at the sizes you are talking about you will be looking at a looooooooooong payback period versus running the ac in mild weather. Not to mention the cost of the fan itself and other materials (grills/registers, tape, mastic etc.) to install it and time to install.

[ProperVenting]

With the price of sheet metal and fab work, metal prefab duct, flex duct, duct board and/or canvas connectors at the sizes you are talking about you will be looking at a looooooooooong payback period versus running the ac in mild weather. Not to mention the cost of the fan itself and other materials (grills/registers, tape, mastic etc.) to install it and time to install.

Aren't we presumptuous again??!! You have no clue who I am and what my connections and capabilities are. Despite the fact that you are in a business, I can probably buy everything that you buy and pay 40-70% of what you are paying, in some cases even less. I would never hire you to do the job @ the rate you are currently charging your poor customers. How that grabs you, braggart? Seems like I have to place you immediately on my ignore list and that is where you belong as far as I am concerned. Keep up guessing.

[jtrammel]

I'm assuming you are doing the work yourself, and still you are talking about a good amount of time and money for little gain.

[ProperVenting]

24" will work. You still want it to make 2 90° bends. Velocity is up a bit, but should be ok.

Best to just call around and get the actual prices to know what the difference will be.

Can I split the main trunk in 2 trunks of 12" each and distribute evenly the rest of space between them? I realise that I still have to do 90 bends. TIA

[ProperVenting]

Can I split the main trunk in 2 trunks of 12" each and distribute evenly the rest of space between them? I realise that I still have to do 90 bends. TIA

Sorry for bothering you with this stupid question, should have thought about that before asking as there is no mathemetical correlation and 2 12' pipes won't be even close to what I need. I guess, I need, at least 2 18" trunks, right?

[beenthere]

Yep, it would take 2-18".