Water Pump - max distance

[VeggieBullet]

with no luck we tried to find some info related to the max distance between the fresh water tank and the water tank.
We saw some nice high end 5th wheels set ups in the RV show in Tampa and we got inspired for the Avion.
One of the thing that got my attention was a 5th wheel that had the water pump, central vacuum and some other things in the basement area.
Also noticed that the fresh water tank was under the same "basement" area.
We got the Flojet 03526144: 2.9GPM/ 50psi and nowhere online we can find any info regarding the "max distance", so I guess it doesn't matter?
thanks for any input

[RickDavis]

There should be specs in the pump manual.
The distance is probably not important between the pump and the tank. The difference in height between the pump and tank (lift) should be kept small which is not a problem usually in an RV. After the pump, no problem.
If the pump doesn't prime the first time on startup opening a faucet usually helps

[VeggieBullet]

Hi Rick
We looked everywhere in the manual and even online but there is no info regarding the max distance nor the height diff.
We will like to see if we can accommodate it in the front basement to make it nice and clean, to don't loose any space inside the trailer and to be easily serviceable, but the distance is about 30ft...

[Wazbro]

Found this quote in an add for your pump.

Three chamber diaphragm design
Self-priming up to 9 feet suction lift;
Pump able to run dry without damage

http://www.ebay.com/itm/Flojet-12-Volt-RV-Marine-Water-Pump-2-9-GPM-Triplex-03526-144A-/200837752319?pt=Boat_Parts_Accessories_Gear&vxp=mt r&hash=item2ec2dce5ff

Sounds like it shouldn't be a problem with a 30' run since I doubt you will have more then a 2' lift to the pump while it's in your basement.

[Protagonist]

Suction lift, A/K/A hydraulic head, isn't quite as simple as all that. 9 feet of lift means that if you're pumping straight up, you can pull the water up 9 feet from the inlet to the pump, before the pump starts to cavitate.

To find out ouw far you can pump, you need to know the pump's discharge head rating. In general, though, for pumping a long distance, the pump needs to push the water, not pull it, to avoid cavitation.

[VeggieBullet]

Originally Posted by Wazbro

Found this quote in an add for your pump.

Three chamber diaphragm design
Self-priming up to 9 feet suction lift;
Pump able to run dry without damage

http://www.ebay.com/itm/Flojet-12-Volt-RV-Marine-Water-Pump-2-9-GPM-Triplex-03526-144A-/200837752319?pt=Boat_Parts_Accessories_Gear&vxp=mt r&hash=item2ec2dce5ff

Sounds like it shouldn't be a problem with a 30' run since I doubt you will have more then a 2' lift to the pump while it's in your basement.

thanks just asked them a question that Protagonist probably answered

Originally Posted by Protagonist

Suction lift, A/K/A hydraulic head, isn't quite as simple as all that. 9 feet of lift means that if you're pumping straight up, you can pull the water up 9 feet from the inlet to the pump, before the pump starts to cavitate.

To find out ouw far you can pump, you need to know the pump's discharge head rating. In general, though, for pumping a long distance, the pump needs to push the water, not pull it, to avoid cavitation.

just asked the ebay seller if the 9ft means total distance or elevation but it looks like the distance.
We noticed that most of the times the pumps are relatively close to the tanks and therefore our inquiry

[idroba]

If you are considering running a 30' suction line from the tank to the pump I would strongly advise you use a larger pipe than the typical 1/2" line. The pump has a lift (the 9' indicated) but also some friction is involved in the suction line which will essentially eat up some of that ability to lift vertically. Probably a 3/4" suction line with minimal fittings would work, but I would do a dry run prior to building a final system and finding it didn't work well. You are asking the pump to both pull a lot and push a lot and may exceed the capacity.

[TG Twinkie]

You will also need a supply line to the pump that will not collapse when suction is applied. PEX would work.
A good test would be to install the line, then fill the tank to 1/4 full. Open the supply line valve (if applicable) measure the amount of water that will flow out of the line freely with just gravity with the tank 1/4 full. If you can get 1/2 the capacity of the pump with just gravity, I don't think even a 1/2" supply line would be a problem. These are pretty low capacity pumps.
Of course if the tank is below the level of the pump location. All of the above is mute.