2in sweep elbows vs 2.5" hard elbows

[goku]

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Inspired by this thread Here. As much as I appreciate that the builder tried to reduce TDH of their plumbing by using sweeps, I have a question to ask. If straight 2in plumbing provides sufficient low loss of head for a given amount of flow (5fps) but every time you add a 90 elbow it adds unacceptable head loss while a sweep provides a moderate reduction of headloss, why not for the sake of better plumbing flexibility upgrade to 2.5" plumbing and then use simple hard 90 degree elbows?


Isn't 2.5" plumbing with hard 90 degree elbows better than 2" plumbing with 90 degree sweep elbows? Again, this is assuming 2in plumbing is sufficient if there were no 90 degree elbows plumbed anywhere. I mean aren't sweeps a bit expensive? yet going with larger plumbing with standard elbows not only is more flexible but cheaper as well?

 

[mas985]

Welcome to the forum!

Isn't 2.5" plumbing with hard 90 degree elbows better than 2" plumbing with 90 degree sweep elbows?

Yes. Especially when most sweeps are DWV pipe which has a narrower glue area. I think sweeps are a waste of money and "space". The amount of head loss change is not going to be that much and the extra space they take up could end up requiring more bends. A sweep or 45 basically cuts the head loss of a 90 in half but the head loss of a single 90 isn't all that bad to begin with. A 2" 90 is worth about 6' of straight pipe. Not all that unacceptable in my book.

Plus reducing head loss actually causes a pump to increase flow rate which increases energy use. So unless the owner makes changes to run time or RPM (with a VS), which is unlikely, they will end up using more energy not less.

 

[Sseaman]

I don't think sweeps have the same pressure rating