Water pumps, pressure and potential issues?

grantgoold · September 01, 2014, 02:47:14 PM

I am beginning the design of the water and waste system for the bus. The black tank system is straight forward and the grey will empty (by valve) into the black for better washout. Now, I am thinking about two different pumps for the fresh water. I was thinking a new 12volt high volume flojet with accumulator tank (part #02090-118) and then on a separate line a 115 volt Shurflo park model (Shurflo Park Trailer Revolution RV Pump 3.3 GPM 115 V 4008-171-E65). I am thinking when I am plugged into power I can run the 115 volt full-time and save the 12 volt for over the road? Not sure I need the accumulator tank as both pumps suggest no real change in faucet pressure as stand alone pumps.

The high volume 12 volt puts out 4.5 gpm max flow rate at 10 psi and the 115 volt is 3.3 gpm at 55 psi.

What kind of problems do you see in this mixed system?

Thanks

Grant

chessie4905 · September 01, 2014, 03:25:04 PM

I'd just use the Sure-flo and keep it simple, like millions of campers and motor homes use. Install a switch near or in your convenience panel to shut it off when away from the coach in case a leak develops in a line somewhere. 3.3 gallons per minute is plenty. Install an accumulator tank to eliminate pulsations and pump run time. Available at Camping World as well as rv dealers.

BeastMaster · September 01, 2014, 05:27:28 PM

Not sure I would install a 110 volt pump. When I'm on shore power I use their water through filters and regulator.

mung · September 01, 2014, 05:38:59 PM

That is one of the things that is interesting, on boats we typically will use a small 12v pump at the faucet that is activated by a switch on the faucet. Not a ton of water flow, but you also don't want to drain your tanks in 2 seconds. On most RVs I have seen, it is a big pump on the tank that is more like a house setup. On the RV if you aren't at a camp site, the issue is less about draining the water tank, but more about filling your waste tanks. On boats, you typically just dump sink water straight out of the boat.

Anyway, if my plumbing wasn't already set up, would probably go with the point of use type pumps used on boats.

Vern

HB of CJ · September 02, 2014, 05:03:40 PM

I just have one odd ball question. If your gray tank dumps into the black tank via a valve, does that imply that it is gravity feed...or is it pumped? If it is gravity feed, could you have a situation where gases/fluid/stinks back pedal into the gray tank when the gray tank is dumped into the black tank? Then what happens? Just wondering; I do not mean to nitpik. HB of CJ (old coot)

TomC · September 03, 2014, 06:26:29 AM

I have two Whisper Quiet Shurflo water pumps in parallel to increase flow, not pressure. Hence, I don't get fluctuations when taking a shower and someone else is using the sink. Then you automatically have a second pump if one quits, or starts to leak-which has happened. Just use the 12vdc pumps, they take very little to power-and then you have more choices. Although I can, I do not hook to city water when on the power pole. I just fill the tank and always use the pumps. Then when leaving for the day to tour, you simply turn off the pumps and don't have to worry about anything bursting.

As to the gray tank-fine to have it dump through the black, but also make sure you have a dedicated dump for the gray. You usually fill the gray before the black. I also have an open dump on the passenger side for discretely dumping the gray into a drain if need be. Good Luck, TomC

bevans6 · September 03, 2014, 08:00:03 AM

10 psi is too low for a shower, you really need at least 35 psi for a good result. Nor do you need a high flow pump, unless you are transferring fluid from one tank to another for some reason. The 12V units can be relied on for very long term usage and a simple, basic system often is better than a fancy system at the end of the day.

Brian

Scott & Heather · September 03, 2014, 08:45:37 AM

We installed a 115v flojet from Lowes. It was great...you could put out a fire with all that water and pressure. Problem is, it was loud, huge (took up too much room) and this past winter it froze and cracked open the pump housing. I'm going with a smaller pump this time around. We aren't wired at all for 12v, so we have to go 115.

Beesme · September 03, 2014, 04:31:58 PM

Great ideas . I sometimes have the pulsing when dry camping . Never when hooked up at site because of their pressure. but I do have another 12v pump sitting in garage ,I am going to try parallel with other pump and see . And the if need be try accumulator ! But other pump is free at this time . Thanx for the ideas

Scott & Heather · October 12, 2014, 04:47:13 PM

Ok, update. Installed a new 110v pump from lowes. Different model. Quiet!!! Turned up the pressure switch slightly and have a small accumulator tank. No pulsing, excellent pressure (seriously better pressure than most people's houses or hotels...seriously) and it doesn't take up tons of room. Just a thought

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LuckyChow · October 12, 2014, 06:34:16 PM

Scott, would you share the model with us please. I'm in a similar setup with no 12V available.

Dave5Cs · October 12, 2014, 07:05:58 PM

Grant,
We have the 12 volt Surflow with another one we carry just in case. So far no problems. Also have a ball valve that we turn one on and shut other one to off and bipasses the tank and comes in through the filter still but directly from the campground supply. When on the road we reverse the ball valves and use the tank water through the pump. No problem with pressure. We use a pressure water regular and set it at 45 lbs from the CG supply.

On the Black and the grey, they each have their own DW Valves all 3 inch type and the drain into a common pipe which has a master valve at the end of it. I drain just the black through its valve into the common pipe with the grey closed. When it is done I open the grey but close the main drain and the grey goes through the black to help wash it out then I open the main again and it all comes through. I also put a 3 inch threaded ABS fitting in the tops of the two tanks so I can spry them out with a water pressured spinner hose thingy ( sorry don't know what they call them CW) . It clean out anything left if there is. Close all valves, put the top caps back in clean up and done.

I also use a 3/4 inch Disposerator and can use up to a 150 foot 5/8 hose if needed to drain the black or leave open for the grey.

Dave5Cs

TheHollands! · October 12, 2014, 08:22:11 PM

Scott, what do you all do when running down the road for water? I'm not setup yet for 12v the way I'd like to be but I do have a single 12v car battery just for my pump. It's simple and works great. Craig

Scott & Heather · October 13, 2014, 09:05:22 AM

Sure...let me check the model as soon as I get to lowes. Bus is in the shop 2 hours away. Craig, 3300 watt generator

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akroyaleagle · October 13, 2014, 04:30:14 PM

We have a 5.7psi pump. No pulsating. Use park water if available.

I never understood the need for the accumulator tank. It might work to stop the pump from coming on each time you get a drink, but pulsating is caused by low pressure not accumulated water.

The 120v pump also eludes me.

I have two pumps plumbed in but one is just a spare. I have changed enough pumps in the rain when I'm soapy that quit because we spent all summer (or winter) hooked to shore water.