So my pump only has a 1.5” input. Return line from skimmer is 60’ to pump dead straight. I would like to use 1.5” line from skimmer to pump and 1.5 to both return jets. Are there any issues here? Thanks guys, and gals.
small pool, 3/4hp pump 1 skimmer and 2 returns. Suction line size?
- Thread starter uxbridgechris
- Start date
2" pipe gives you better flow due to less resistance. 2" pipe has a negligible cost increase. So, it's all benefit for almost no cost.
Will you have a main drain?
Will you have a main drain?
I'm having trouble grasping this. I know the accumative effect of elbows adds head. completely understandable. But does a 6" pipe that is reduced to 1.5" have less resistance than a 1.5" pipe? hard to wrap my head around it.
The resistance of a pipe depends on the flow rate, pipe diameter and pipe length.
For example, 100' of 1.5" pvc pipe at 50 gpm results in a water velocity of about 7.88 ft/sec and a head loss of about 15.4 ft.
However, 99 ft of 2" pvc at 50 gpm has a head loss of about 4.8 ft and 1 foot of 1.5" has a head loss of about 0.154 ft for a total head loss of about 4.954 ft or about 1/3.
So, you get more flow.
To get a better idea of the dynamics, you can graph various system curves on the pump curve chart to see where various system curves intersect with the pump curves and choose a good pump and pipe size based on the desired flow rate.
The 2" pipe will have a lower, flatter curve vs a 1.5" pipe, which would have a steeper system curve.
For example, 100' of 1.5" pvc pipe at 50 gpm results in a water velocity of about 7.88 ft/sec and a head loss of about 15.4 ft.
However, 99 ft of 2" pvc at 50 gpm has a head loss of about 4.8 ft and 1 foot of 1.5" has a head loss of about 0.154 ft for a total head loss of about 4.954 ft or about 1/3.
So, you get more flow.
To get a better idea of the dynamics, you can graph various system curves on the pump curve chart to see where various system curves intersect with the pump curves and choose a good pump and pipe size based on the desired flow rate.
The 2" pipe will have a lower, flatter curve vs a 1.5" pipe, which would have a steeper system curve.
I would say that 1 1/2 inch pipe would be fine for a 7000 gallon pool. The flow rate needed for good circulation and overturn on that size pool will not be impaired, especially with your large filter.
cfherrman
TFP Guide
Pool gallons do not matter when sizing pipes, neither does turnovers.
To really answer the question, what kind of pump do you have, need a head count.
Either will work, I'll edge on the 2" due to the long run.
To really answer the question, what kind of pump do you have, need a head count.
Either will work, I'll edge on the 2" due to the long run.
You get better flow with 2" pipe. So, you can use a smaller pump or less run time or a lower rpm if it's a variable speed pump.
Good hydraulic design is to keep the suction line water velocity to less than 6 ft/sec.
At 1.5", the velocity will exceed 6 ft/sec and at 2", the velocity will be less than 6 ft/sec.
Since the cost for 2" vs 1.5" is insignificant, I don't see any benefit to using 1.5" pipe.
Good hydraulic design is to keep the suction line water velocity to less than 6 ft/sec.
At 1.5", the velocity will exceed 6 ft/sec and at 2", the velocity will be less than 6 ft/sec.
Since the cost for 2" vs 1.5" is insignificant, I don't see any benefit to using 1.5" pipe.
Ok, so part the reason I even asked the question was because I was having a real hard time sourcing 2" locally. I have found it so it's a no brainer.
2" from skimmer to pump.
All 2" between pump, filter, Heater and SWG. 2", 3 way valve with outputs reduced to 1.5", then 1.5" lines to both returns.
Thanks guys
2" from skimmer to pump.
All 2" between pump, filter, Heater and SWG. 2", 3 way valve with outputs reduced to 1.5", then 1.5" lines to both returns.
Thanks guys
Well, that would certainly surprise engineers who deal with such matters.