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how to calculate resistance (head?) for a 180 degree turn return 3/4" pipe
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iexpl
Member Posts: 48
Like @EdTheHeaterMan posted in this photo, how to model the resistance for these 180 degree turns of the copper pipe? What happens if this is a PEX pipe? Is there some specification somewhere I can look at?
Many thanks.
Many thanks.
0
Comments



I see. So, with a 6" radius for 3/5 copper, I would need the supply pipe 1 ft off the floor to give the 6" turning raidus. Do I interprete it correctly?0

Hi, My understanding is that if the radius of the bend is five times (or more) the diameter of the pipe, the water no longer knows it's changing direction and the friction loss is only equal to the length of the pipe.
Yours, Larry0 
Thanks @Larry Weingarten @hot_rod @Jamie Hall for answering. So, if I do not want 1 ft high baseboard off the floor, I will have to curve the turn with smaller radius, I just model it as 2 90 degree elbows, which adds 2 ft head each with the total of 4 ft head, right?0

Got itBr. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 
long sweep copper ells would have a lower pressure drop. You may find charts with the EL of longer sweep ells. I suspect the sweep ell may be 1/2 the flow resistance of the typical copper ell?
I doubt you would get enough of a sweep radius inside a typical fin tube enclosure to get 0 pressure drop. If that is where you are headed?
I don't remember where the radius number comes from. Either the Copper Tube Handbook bending section 4, or maybe the REMS tube bender tech sheet. I don't know there is an exact multiplier??Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 
You might have enough space to do this with a large enough radius:
0 
The copper 90's do not add 2 feet of head, they add 2 feet equivalent pipe length. Make sure when you are adding the fittings that if the value of the table you are looking at says "equivalent length" you are not counting that as feet of head or you will end up with a massive pumpiexpl said:Thanks @Larry Weingarten @hot_rod @Jamie Hall for answering. So, if I do not want 1 ft high baseboard off the floor, I will have to curve the turn with smaller radius, I just model it as 2 90 degree elbows, which adds 2 ft head each with the total of 4 ft head, right?
3 
like thisBob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 
What are you trying to accomplish? Unless you are dealing with a monoflo system or something only very rough calculations are usually necessary especially with adjustable ECM circulators.0


use regular tees and put a balancing valve in the main between the tees then you can use the balancing valve to effectively make the monoflo orifice whatever size you want.0

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