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friction loss
smklin
Member Posts: 69
I am wondering how much friction loss i have i my heating system.
710' of 2'' pipe
2 2" 45 degree elbows
21 2" 90 degree elbows
and then i have 3 2" close return bends where the water makes a 180 degree turn
710' of 2'' pipe
2 2" 45 degree elbows
21 2" 90 degree elbows
and then i have 3 2" close return bends where the water makes a 180 degree turn
0
Comments

what
kind of pipe? Also what flows rates do you want to look at? Just a guess will help.0 
50 GPM
I HAVE 50< GPM
BLACK PIPE SCH 400 
Resistance
At 50 gpm I came up with 4.66 ft of head/100 ft for 2" pipe.
After converting the fitting footage to ft of pipe the total equivalent feet came out to 919 ft including the 710 feet of pipe.
919 ft @ 4.66/100 ft =42.8' of head. the fitting chart I had showed 8.5 equivalent feet for a 2" screwed 90. This seems high to me.
What do you guys show for a 2" screwed 90?0 
Ell
B&G lists 5 equivalent feet for a 2" screwed 90º ell .bob0 
pump
what pump will work on that0 
Pump Curve
Go on Taco's web site and use their pump sizing tool.
I question using 2" for 50 gpm on a hydronic line. Your velocity maybe too high.Bob Boan
You can choose to do what you want, but you cannot choose the consequences.0 
pipe velocity
At 50 gpm you are getting about 5 ft/s. Might be too fast? If you reduce your velocity your head loss will go down too.0 
How much flow do you actually need?
Reducing flow and increasing ∆T will result pretty big wins both for first cost and electrical usage.
50 GPM = 42.4 feet (say 20ºF ∆T)
40 GPM = 27.9 feet at 25ºF ∆T
30 GPM = 16.3 feet at 30ºF ∆T0 
< 50 GPM
I need 50 gpm. IF I COULD GET 60 I PROBABLY WOULD TAKE IT.0 
Options
in order of preference:
Reduce the GPM requirement (where did that come from, BTW)? Increase the ∆T, possibly with hydraulic separation and additional pump(s) downstream.
Replace as much of the run as practical with larger diameter pipe. Still better to isolate and branch where practical.
Install a big pump, eat the electric costs  and be prepared for erosion corrosion.0
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