Wells, Sump Pumps and Septic Sewage Systems - Pump sizing question
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dashingdave
10-28-09, 07:04 AM
I've just pulled a 1 hp 3 wire sta-rite pump from a 315 foot well. This well has always yielded well and I'd like to put a bigger pump down the shaft because of higher water needs on our farm. The wire size is #10. Are there issues with dropping a 1.5 or even 2 hp pump down this shaft?
Also, can someone explain all the differences between pump specs? For example, how is my 1 hp pump adequate for that depth yet some 2 hp pumps are only rated for 200 foot of head.
Thanks, Dave
Also, can someone explain all the differences between pump specs? For example, how is my 1 hp pump adequate for that depth yet some 2 hp pumps are only rated for 200 foot of head.
Thanks, Dave
Bud9051
10-28-09, 08:16 AM
Hi Dave and welcome to the forum,
One or more of the well pros will be along, but your pump is sized base upon the capacity of the well, at least the max size of the pump. If the pump you have was installed because a larger one simply wasn't needed at the time, then you just have to establish if the well can handle a larger pump. If you go too big, you risk pumping the shaft dry or two low and damaging your pump.
As for the lift, I believe it is the distance above the water level in the well. Your pump/well may be down 315 feet, but the lift may only be the top 100 ft. Thus one of the concerns for the oversized pump.
The pros should be by
Bud
One or more of the well pros will be along, but your pump is sized base upon the capacity of the well, at least the max size of the pump. If the pump you have was installed because a larger one simply wasn't needed at the time, then you just have to establish if the well can handle a larger pump. If you go too big, you risk pumping the shaft dry or two low and damaging your pump.
As for the lift, I believe it is the distance above the water level in the well. Your pump/well may be down 315 feet, but the lift may only be the top 100 ft. Thus one of the concerns for the oversized pump.
The pros should be by
Bud
waterwelldude
10-28-09, 08:39 AM
Bud pretty much summed it up.
If your well will produce the water you need, there is no problem with installing a larger pump.
We have 5hp pumps that produce over 100gpm in a 90', 4" wells, but the water level is around 15 to 20 feet from the top.
The size of the pump is mostly related to the depth of water in the well, the production rate of the well, and the amount of water needed.
All of this is taken into account when sizing the pump.
A 1hp 10gpm sub. is fine for most houses.
If say, a sprinkler system is added, a 1.5hp 30gpm can be used with out any issues at all.(provided the well can produce the amount of water needed).
The wire you have #10awg should be fine for up to a 2hp at the depth your pump is set now.
Travis
If your well will produce the water you need, there is no problem with installing a larger pump.
We have 5hp pumps that produce over 100gpm in a 90', 4" wells, but the water level is around 15 to 20 feet from the top.
The size of the pump is mostly related to the depth of water in the well, the production rate of the well, and the amount of water needed.
All of this is taken into account when sizing the pump.
A 1hp 10gpm sub. is fine for most houses.
If say, a sprinkler system is added, a 1.5hp 30gpm can be used with out any issues at all.(provided the well can produce the amount of water needed).
The wire you have #10awg should be fine for up to a 2hp at the depth your pump is set now.
Travis
shane21
10-28-09, 11:12 AM
#10 wire is rated for 390 TOTAL feet of run for a 2 HP pump. You need to know how deep it is set AND how many feet the underground power runs from the source to the well. Add the 2 up and you get the total length. If you post that total distance and are sure the underground wire is #10 also I will be happy to help you figure the max motor you could install.
If you pulled the pump already how deep was it set? Also if you have a copy of the original drilling log it should indicate the static level, test rate and draw down during the drilling process and we can probably estimate the well yield.
Lastly the head rating of a pump is determined by the pump size relative to the motor size. At any given motor HP rating there will be a trade off of flow vs pressure. For instance a 2 HP 10 GPM is rated at 700 feet TOTAL head, a 2 HP 25 GPM is rated at 350 feet TOTAL head and a 2 HP 60 GPM is rated at 190 TOTAL feet of head.
To size the pump you need to know how far down the water level drops at your required flow rate and adjust the sizing to include that plus the desired pressure on the system. If you can find a copy of the original drilling log we can probably help you decipher all of the info.
If you pulled the pump already how deep was it set? Also if you have a copy of the original drilling log it should indicate the static level, test rate and draw down during the drilling process and we can probably estimate the well yield.
Lastly the head rating of a pump is determined by the pump size relative to the motor size. At any given motor HP rating there will be a trade off of flow vs pressure. For instance a 2 HP 10 GPM is rated at 700 feet TOTAL head, a 2 HP 25 GPM is rated at 350 feet TOTAL head and a 2 HP 60 GPM is rated at 190 TOTAL feet of head.
To size the pump you need to know how far down the water level drops at your required flow rate and adjust the sizing to include that plus the desired pressure on the system. If you can find a copy of the original drilling log we can probably help you decipher all of the info.
dashingdave
10-29-09, 07:51 PM
Thanks, guys for your responses. I ended up buying another 1 hp pump with a higher yield curve than the one I'm replacing. Now I've just got to drop that baby back in the hole.
waterwelldude
10-29-09, 08:59 PM
The one you bought, will it deliver a higher yield from the same depth as the old one?
Is it a higher volume or higher pressure?
With a deep setting pump there is a trade off between pressure and volume, with the same hp motor.
Does the curve of the new pump show it will deliver the water you need at the pressure you need from the depth it is set at?
Travis
Is it a higher volume or higher pressure?
With a deep setting pump there is a trade off between pressure and volume, with the same hp motor.
Does the curve of the new pump show it will deliver the water you need at the pressure you need from the depth it is set at?
Travis
shane21
10-30-09, 05:12 PM
WWD,
I'm guessing it won't fit his needs as about any jump in pump size I can think of on a 1 HP motor will GREATLY reduce the TDH. You have to assume it was sized fairly accurately when installed so jumping from a 10 GPM to even a 15 GPM will almost certainly give him problems. If the original was a 10 GPM and he put in an 18 GPM I can guarantee he will be back here asking why his pressure switch won't ever turn off :)
I'll be watching this thread to see if he comes back.
I'm guessing it won't fit his needs as about any jump in pump size I can think of on a 1 HP motor will GREATLY reduce the TDH. You have to assume it was sized fairly accurately when installed so jumping from a 10 GPM to even a 15 GPM will almost certainly give him problems. If the original was a 10 GPM and he put in an 18 GPM I can guarantee he will be back here asking why his pressure switch won't ever turn off :)
I'll be watching this thread to see if he comes back.