Location of Water Pump?

[Midwilshire]

We are mounting our Flojet water pump this weekend.  The manual says it's "self priming to 10 feet" without further explanation.

I built a shelf for it in the most-convenient and out of the way location, which turns out to be just above tank height about one foot above the water line.    This pex run from the tank outlet to the pump inlet would have about five horizontal feet and two vertical feet. 

Will this work, or do I need to put the pump on the bay floor below the water line? 

Thanks in advance.

Mike

[bevans6]

I would definitely try it.  The pump head is measure above the water level in the tank, so you would have up to two feet.  Once it's primed the first time it should hold prime.  If it doesn't hold prime then for convenience I might move it down to where it has a positive head pressure on the input.

Brian

[lostagain]

Mine is above the top of the tank by a few inches and works fine.

JC

[sparkplug188]

"self priming to 10 feet" means it can pull water up though 10 feet of vertical pipe on the inlet.  You shouldn't have a problem with 7 total feet of pipe and only 2 feet of vertical difference.

[Midwilshire]

Thanks guys!

[HB of CJ]

Ten feet of self prime is not all that much which may indicate a semi functional self priming pump.  It is not so much the lateral suction draft as the vertical suction lift.  The lower you can mount the pump, the better it will work, the less energy it will require, the longer it will last and the more water it will pump.  I would mount it as low as possible. 

Your plumbing arrangement might require the inlet suction pipe to enter the top of the water tank, which would reduce potential leaks.  Also consider the larger diameter suction pipe from the tank to the pump.  Also consider using gentle "sweeps" instead of abrupt right angle fittings.  Consider a fil-ture.  PEM me if you want.  HB of CJ (old coot)

Ah ... Lennix Firefox Mozilla British Speeel Chezk.  Cousins across the sea separated by a common spoken language ... I think.   How do you spell filture?

[Dave5Cs]

Ours is on the bay floor at bottom of tank and then out 3 feet and up 3 feet into coach with no problems because it still has to go up 6 feet more to top of shower head and still no problems.

[Iceni John]

Ah ... Lennix Firefox Mozilla British Speeel Chezk.  Cousins across the sea separated by a common spoken language ... I think.  How do you spell filture?

How true.   When I worked on rigs in the North Sea we had crew from Louisiana and Mississippi, and also some local crew from Liverpool in England and Aberdeen in Scotland.   The 'Mericans couldn't understand a word of what the Scousers were saying, and I couldn't understand what the Scots were saying, even though we were all theoretically speaking the same language.   Our Australian Rig Superintendant couldn't understand any of us, and used to start mumbling in Strine after a few minutes with the Louisianans.   The few Dutch on board were the only ones who spoke good English (apart from me!).

Ah yes, water pumps.   Mount them as low as possible, with somewhere for the inevitable leaks to harmlessly drip to ground without flooding a bay.   Make them easily accessible, because sooner or later you'll need to swap or repair one when a chunk of something gets caught in the diaphragm or check valve.   Strainers are well worth it to minimize FOD.

John

PS  -  HB, it's spelt Eff Eye Ell Tea Eee Aaargh.

[TomC]

I use two Shurflo Whisper Quiet standard switch (most reliable) water pumps that are mounted at floor level with the water tank. Both or either can be used at the same time. They only put out about 30psi, but it's enough. If you do mount the pump below water level, put in a valve on the intake side so you can turn off the water to the pump incase of leak, but still be able to use the water system. I had one of my pumps leak and simply turned off the valve and continued on the trip-replacing both pumps when we got back home. Good Luck, TomC

[HB of CJ]

Got it.  I hate getting old.  There seems to be some confusion here regarding pump specs and what they may or may not mean which will result in how they may or may not perform ... or at all. 

A pump rated to pull "UP TO" 10 feet of draft or suction, (fire department stuff) won't.  The key words here are "UP TO".   At the aforementioned 10 feet of suck, (draft) they may or may not work at all.

Let us keep this simple.  I used to teach this stuff at the fire academy and I tend to get wordy.  For any pump to suck or draft or lift water 10 feet means it needs to be in perfect shape ... or nearly so.

Once wear takes place, or any slight damage, all specs are off.    Lifting water is not the same as pressurizing water.  A common cheap diaphragm lift pump might put out about 60 psi pressure, which ...

... Will pump water, (lift it up higher) to about 125 feet.  What the question was will his 10 foot lift pump work in a Bus Conversion.  Yes, maybe, no and never.  Dynamic situation.  Mount the pump low.

If you have the suction pipe going directly, (sideways)  (British Speeel Chez)  then the lateral length of pipe does not matter that much.  Diameter does.  Makes the suck pipe larger in diameter.

This is very important in a Bus Conversion.  Small suction pipe diameter will kill pump performance and life.  Makes it work too hard.  If possible, go to a larger diameter pipe.  Even a little bit helps.

Next comes the necessary, (probably with top mount suction pipes) bends and corners.  Try using gentle sweeps instead of abrupt right angle direction changes.  This is vital when using small diameter suction pipe.

A gate value between the pump and the tank makes sense when leaks occur and you do not want flooding.  But ... this may only be necessary if the suction intake pipe is horizontal.  Gate valves are optional.

Mount low.  Use large diameter suction pipe with gentle bends.  Less suction resistance.  Use only 1% 12VDC voltage loss in the wiring size.  Not 3% or 5%.   Consider a good FILTER.  ANY debris is not good.

Different combinations of using too small of wiring, too small of suction pipe, too many sharp suction pipe corners and too much lift, (pulling the water up out of the tank) will defeat most all self priming pumps.

End of lecture for today.  I love this Bus Conversion forum in spite of being ... BUSS-LESS!  But maybe not for long.  Another Crown Supercoach Bus Conversion would be so much fun.  What bank account?

[Seangie]

My pump said the same thing when I mounted it (2 feet above the bottom of the tank)

I didn't realize until shakedown that it would suck from that level but then all the water would drain back into the tank till it leveled out again and then I'd have air pocket problems...it was a mess.  I ended up replumbing and putting the pump head at the same level as the bottom of the tank and no problem.

It just sucked cause the day I had to do that was 4 days before we moved out of the house and the pressure was on!

-Sean

Wandering the country in a 1984 Eagle 10S. 
www.herdofturtles.org

[thomasinnv]

Another thing to consider.....a pump that may "draw" up to ten feet wont necessarily "self prime" up to ten feet. I work on rv's in the winter down in Q-town and i see a lot of pumps that wont prime but once they get going they work fine.

[Midwilshire]

I didn't realize until shakedown that it would suck from that level but then all the water would drain back into the tank till it leveled out again and then I'd have air pocket problems...it was a mess. 

I wonder if putting a check-valve near the tank would prevent that? 

I built this nifty, out-of-the-way shelf for the Flojet, and the only low place to mount it is right where we were going to store hoses, etc, which is less-elegant.  But these good responses to my initial question, including HB of CJ's lecture, are making me think I'd better play it safe and mount it low. 

[digesterman]

I have used SureFlows for over twenty years at my cabin, two on the suction side to fill my treatment tank, these two draw or suck about 5 feet through filters, and two more on the supply side drawing another 4 feet then providing water through a series of filters to the house. I have only lost one pump in twenty plus years out of the original 4. For that reason I would highly recommend SureFlows. FWIW I wouldn't rebuild any of them, cheaper just to buy new ones. I have two in my bus and have not had any issues.


Sent from my iPad using Tapatalk