I’ve never done anything like installing metal pipe, but have put some together for this job and although I actually think it is fun, I’m running out of time on the install…SO: In thinking about how I can make it go faster, I’m trying to make a call on how much flex pipe I can get away with using without destroying airflow. Unit is slightly oversized for the house size but I am under deadline to get this done this weekend before Insulation sub shows up. It’s mostly needed between floors to avoid lots of turns.
Edited 11/22/2005 9:43 pm ET by Merle
Replies
What size of pipe are you talking about going to flex with?
Here's a few rules of thumb about ducting:
1) an elbow has as much resistance as 10 ft of straight pipe.
2) spiral FLEX pipe has twice as much resistance as smooth pipe
Some companies used to give the maximum total equivalent length for the longest/worst run of pipe to a room. More that the given equivalent and rated air flows would start to suffer.
Since the machine is oversized, it may be able to push enough air on low speed and be a bit noisy on high speed (which is used rarely anyway)
THANK YOU so much for your reply,
I am taking 3.5x10" to 6" via flex up through the floor creating a kind of S shape, and then I have also connected 6" to 6" with ~ 2 to 3 foot sections of flex up to open trusses. I have used flex instead of 90s in 4 places to cut down on connections and the cost of the shapable parts.More info is appreciated as once this is convered over...if this is wrong I must redo it.I also have T's carrying through to several rooms....Is there a way to know how the air flows in a T situation? I was assuming the air split each way, but now I see that may have been naive. How to assure the air will pull though T's evenly?I am splurging all seams and connections with mastic and taping over and using hose clamps in addtion for the flex. I am not going to be able to test the system before the ducting is covered over with insulation, so is there any way to test for leakage?