Previous in Forum: Clculation of Reynolds Number   Next in Forum: Fumes Flow
Close
Close
Close
17 comments
Rate Comments: Nested
Associate

Join Date: Oct 2006
Posts: 25

Solar Pump Installation

03/17/2008 5:47 AM

i have installed a surface solar pump 1meter above the water surface, i found it difficult to suck water , what could possibly the problem.. It is use to transfer from lower pond to cascading falls which is only 1.5 meter discharge height.

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Guru
Popular Science - Weaponology - New Member United Kingdom - Member - New Member

Join Date: May 2007
Location: Harlow England
Posts: 16512
Good Answers: 670
#1

Re: solar pump installation

03/17/2008 6:04 AM

Some pumps are not self priming and need to be below the water surface....
Some pumps push better than they suck too.

My pond pump (mains powered) doing a similar task, sits at the bottom of the lower pool to do the job.

Del ( PS. The Frogs say 'hi' )

__________________
health warning: These posts may contain traces of nut.
Register to Reply
Power-User

Join Date: Jan 2007
Location: UK S.Northants
Posts: 485
Good Answers: 19
#2

Re: solar pump installation

03/17/2008 6:09 AM

If mounted above the water, does it need priming? could there be an air leak? My pump is also submersible, so it doesn't have to suck.

Register to Reply
Power-User

Join Date: Jul 2007
Location: The cigarette-stained drunkard living in the cardboard box outside Marks & Sparks delivery entrance, Eastgate Shopping Centre, Basildon.
Posts: 487
#3

Re: solar pump installation

03/17/2008 6:37 AM

This topic sucks. <Splutter>

__________________
Essex jobs for Essex yobs! <Burp>.
Register to Reply
Guru
Engineering Fields - Manufacturing Engineering - New Member Hobbies - Target Shooting - New Member United States - Member - New Member Hobbies - Hunting - New Member

Join Date: Dec 2006
Location: Charlotte, NC USA
Posts: 791
Good Answers: 17
#4

Re: Solar Pump Installation

03/17/2008 11:47 AM

If the pump is large enough for your application, and I assume it is, then I'd look for a leak, it may be sucking air.

__________________
Be careful of what you wish for .....
Register to Reply
Power-User

Join Date: Mar 2007
Location: South East of Las Vegas just far enough to see the lights but far enough to not hear the coins falling
Posts: 282
Good Answers: 8
#5

Re: Solar Pump Installation

03/17/2008 11:18 PM

I would ask, has it ever worked well?

If your answer is no then I say you have a couple of things to consider.

1. Certainly check for leaks.

2. You are at a lost from the beginning because you have no NPSHA, so I would put a "trap" in the pump line and maybe a check valve to hold a porition of water as close to or above the pump inlet to "prime" the pump on start up.

The lack of net positive pump suction head available has to be over come to achieve reliability. Is it possible to bring the pump down closer to the water level or simply install a submersible pump in the lower pond?

Mike

__________________
Rule number one; Never ask a question unless you are prepared for an answer that you may not like.
Register to Reply
Guru

Join Date: Dec 2006
Location: Hop around Toronto, New York & Karachi
Posts: 1876
Good Answers: 19
#7
In reply to #5

Re: Solar Pump Installation

03/17/2008 11:50 PM

Yes U are right.

__________________
I not only use all the brains that I have, but all that I can borrow. Woodrow Wilson
Register to Reply
Power-User

Join Date: Mar 2007
Location: South East of Las Vegas just far enough to see the lights but far enough to not hear the coins falling
Posts: 282
Good Answers: 8
#8
In reply to #7

Re: Solar Pump Installation

03/18/2008 12:16 AM

Thank you Ducon

__________________
Rule number one; Never ask a question unless you are prepared for an answer that you may not like.
Register to Reply
Anonymous Poster
#9
In reply to #7

Re: Solar Pump Installation

03/18/2008 2:15 AM

You are right.

Register to Reply
Anonymous Poster
#10
In reply to #9

Re: Solar Pump Installation

03/18/2008 3:33 AM

No no YOU are right!

Register to Reply Off Topic (Score 5)
Commentator

Join Date: Jun 2007
Location: Missouri
Posts: 86
Good Answers: 1
#15
In reply to #5

Re: Solar Pump Installation

03/18/2008 9:52 AM

NPSHA ????

__________________
I know the rumour is true. I started it and I don't think I would lie.
Register to Reply
Guru

Join Date: Dec 2006
Location: Hop around Toronto, New York & Karachi
Posts: 1876
Good Answers: 19
#6

Re: Solar Pump Installation

03/17/2008 11:50 PM

Pumps work well if the it gets +ve suction head. i.e the suction is below. On above as in your case, it is -ve suction head and will give you problem. It needs first a foot check valve at the suction tip and needs to be primed before starting.

Note. If you do have a foot check valve at the suction tip and still facing problem then that must be leaking. Take it off, clean or replace.

__________________
I not only use all the brains that I have, but all that I can borrow. Woodrow Wilson
Register to Reply
Guru
Engineering Fields - Piping Design Engineering - New Member Egypt - Member - Member since 02/18/2007

Join Date: Feb 2007
Location: Cairo, Egypt
Posts: 1733
Good Answers: 248
#11

Re: Solar Pump Installation

03/18/2008 5:46 AM

May be you have designed and installed your pump with a NPSHA less than the NPSHR. May be reducing the height of 1 m to become 0.5 m or less, may be help in working properly. Or may be the power of the pump is insufficient.

__________________
It is better to be defeated on principles, than to win on lies!
Register to Reply
Power-User

Join Date: Feb 2008
Location: Northeast Ohio, USA
Posts: 267
Good Answers: 9
#12

Re: Solar Pump Installation

03/18/2008 8:42 AM

The answers given so far are all related to the suction problem. Have you considered the possibility that the pump is not capable of overcoming the discharge head (pressure)? There is also the possibility that the discharge is "air locked". Is there a way you can open the discharge line to air and see if the pump delivers then? Perhaps a pipe connection not too far downstream from the pump can be "cracked" to allow the discharge to flow there. As for the NPSH of the pump, one meter is far below the NPSH of any pump with which I am familiar. Required NPSH is customarily quite low, especially when operating on the left side of the characteristic curve of the pump. I would discount that as an option. The "foot valve" is a good idea because it will hold the prime of the pump after it stops. However, as stated by others, the pump must be manually primed to get it started. The most probable culprit is, as some have suggested, air being allowed to enter the suction side of the pump. Check your connections, prime the pump and see what happens. Good luck!

__________________
All that is necessary for the triumph of evil is for good men to do nothing. - Edmund Burke
Register to Reply
Guru
Popular Science - Weaponology - New Member United Kingdom - Member - New Member

Join Date: May 2007
Location: Harlow England
Posts: 16512
Good Answers: 670
#13
In reply to #12

Re: Solar Pump Installation

03/18/2008 8:45 AM

Have you considered the possibility that the pump is not capable of overcoming the discharge head (pressure)?

No

__________________
health warning: These posts may contain traces of nut.
Register to Reply
Guru
Engineering Fields - Piping Design Engineering - New Member Egypt - Member - Member since 02/18/2007

Join Date: Feb 2007
Location: Cairo, Egypt
Posts: 1733
Good Answers: 248
#14
In reply to #13

Re: Solar Pump Installation

03/18/2008 8:52 AM

That is acceptable point, why not?

__________________
It is better to be defeated on principles, than to win on lies!
Register to Reply
Guru
Popular Science - Weaponology - New Member United Kingdom - Member - New Member

Join Date: May 2007
Location: Harlow England
Posts: 16512
Good Answers: 670
#16
In reply to #14

Re: Solar Pump Installation

03/18/2008 1:23 PM

I just didn't feel like it . And I'm familiar with pumps that blow harder than they suck....

It was only s'posed to be a funny comment ... baaad kitty

__________________
health warning: These posts may contain traces of nut.
Register to Reply Off Topic (Score 5)
Associate

Join Date: Mar 2008
Posts: 47
Good Answers: 2
#17
In reply to #13

Re: Solar Pump Installation

03/18/2008 1:32 PM

Some pumps also have check valves in the head that need cleaning sometimes or even reseating. But as always the easiest fix would be to check the prime.

Register to Reply
Register to Reply 17 comments
Copy to Clipboard

Users who posted comments:

Abdel Halim Galala (2); Anonymous Poster (2); ducon (2); foofire (1); HUX (1); Labyguy (1); miketheboilerguy (2); Pebbles (1); Stinky Pete (1); The Commoner (1); user-deleted-1105 (3)

Previous in Forum: Clculation of Reynolds Number   Next in Forum: Fumes Flow

Advertisement