What is better and more efficient, that is the question

[ProperVenting]

So if I have to install WH venting in the attic above 2nd floor, what would be better, - going with smaller individual inline fans for each room with short duct line or install large CWD sidewall mount beast and bring ductwork from all rooms to it? Also how would I control them automatically w/o spending small fortune on thermostats? Any ideas?

[timjimbob]

Still haven't figured what your venting!

[ProperVenting]

Sorry, didn't make myself clear, I am trying to do whole house venting of the 2-nd floor only, bedrooms, bathrooms and catwalk.

[timjimbob]

Then it is half house venting, right?
Individual fans would require back draft dampers and stats, but give you more control. One, giant fan is simpler, but is very limited control.
Better decide what you want before you look for an efficient way to do it.

[ProperVenting]

Yeep. Half the house. How I can decide if I didn't even consider back draft dampers? It appears that I am totally clueless

[timjimbob]

Need to think this out.

What would happen if room #1,2 and 3 are running vent fans but room #4 is not? Exhaust, in room #4, would possible now become supply.

[ProperVenting]

You are absolutely correct, as I said it appears that I'm totslly clueless and didn't understand all the technical challenges. Hmmm...really a bomber. What would you suggest? How about those fans control, any inexpensive thermostats, when I can force all of them @ the same time? Where to position them, I mean thermostats? Under ceiling?

[timjimbob]

Can't help you. Have a HVAC contractor give you some scenarios.

[ProperVenting]

Thanks anyways for your insights

[ProperVenting]

After careful consideration, I am leaning toward powerful inline fan (Fantech FKD series) and bringing inlet registers in each room, however potential cost of just sheet metal alone is quite staggering as I will need huge 14-16" round pipe main trunk of approximately 60 feet plus good size registers in each room (equivalent to 18x18) plus all individual runs of 10" pipe going from main trunk to each room

[timjimbob]

I miss the old attic fans with the shutters that are not used anymore in this area. The soft whirr and fluttering blades was the best sleep aid.

A few years ago, I saw a great setup at the trade show that you may look into. Great invention. It had a motorized damper that opened plenum and ventilated using existing HVAC system and outside air. Don't remember much more.

[ProperVenting]

If you are you referring to this Airscape unit, I am not really thrilled with the idea for various reasons.

[ProperVenting]

Seriously, I think the units like that are totally useless and complete waste of money and I know that there is, at least one more company which makes similar type of product.

[ProperVenting]

After looking more carefully into central point installation, cost and headaches involved with this method are increasing exponentially every day. At this point I'm back @ crossroad.

[54regcab]

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

[ProperVenting]

And how did you figure that out?

[54regcab]

BTDT. I open windows during spring fall when it's cool outside. Sure it saves some $$, but I mostly do it for the fresh air. Check the amount of cycling your AC does on a cool night.