Office and warehouse in both Crystal River & New Port Richey ,FL
Originally posted by alexb Here's a PIC of the end of one of my duct runs.
I know there's do DIY here, but I'm just stating what I've done. I've cut the end off this run, and I'm putting in a 45-degree bend from the main line, to the line dissapearing off the top of the picture. The small 5" round going to the left will be cut off & capped; it goes to a tiny bathroom.
I'm counting on this providing MUCH more airflow to the 15' of duct that connects to the line that dissapears off the top of the pic. I suffer from v. poor airflow in this room; not meeting CFM requirements..
The duct that you refer to will get more air with your changes,but I wouldn't think it would be a lot more ,if that's the end of the only trunk line.
Reason is,it's likely that is the longest run, in Total Equivalent Length(TEL),from the indoor fan.So the changes likely need to be made closer to the indoor fan,to increase the Static available at the end of the trunk.
The "takeoff" fiiting is used there is not a great loss,likely a 45° "bend" may be worse.An unknown is what exactly your 45° turn will look like,and the effect of making the branch duct,more of a trunk duct,ie taking a branch out the end of the trunk,will increase air flow.
You will gain all or most all of what went to the bath.
Turning vanes for the turn would be an improvement,but you need to looh at adding vanes between there and the indoor fan,or some other method to reduce the PD and TEL of the duct ,to get much more air at the "end' of the trunk.