Fresh water pump..

[Iver]

When I had my old S&S, I think I read somewhere it said to turn off the fresh water pump when driving.  Does it matter??  My bus has a "breaker switch" to turn the pump on and off but the switch is not that conveniently located.  What do you do?
        Iver.

[TomC]

Sometimes yes sometimes no.  I haven't had a busted hose yet and I'm using the Qest hoses and fittings.  The main concern is to turn off the water pump when you're not around to keep from flooding the bus in the event of a burst hose or fitting.  Good Luck, TomC

[TomCat]

I haven't turned mine off in about 18 months. I used SharkBite fittings with no problems yet.

Jay
87 SaftLiner

[JackConrad]

Only time our fresh water pumps (we have 2 connected in paralell for more shower volume) have ever been shut off was when we needed to make changes or additions to our fresh water sytem. System has been in the bus since 2000, no problems so far.  Jack

[jjrbus]

 I got lucky and thought ahead on this one. I put my pump switch and water heater switch right by the door. Now when i go out I forget to turn them off and if I do remember, I forget to turn them on when I come back Seemed like a good idea at the time! But eight years with no mishaps on the road.

[Iver]

Ok,  that resolves that one.  I'm pretty sure that all my plumbing is leak-proof so I won't worry about not turning the pump off all the time.
         Thanks.... Iver.

[TomC]

The pump will tell you if there's a leak, by pulsing every minute or two.  If it pulses maybe once an hour, nothing to worry about-as long as everything is dry.  Good Luck, TomC

[gus]

Mine pulses every half hour or so. I figured I have a leak but so far haven't found one so it must be very small

When I got the bus it had a switch under the kitchen sink. I moved it to the toilet wall just a few inches away. Since it was already wired I saw no reason not to keep it.

It is near all water outlets so we only have it on only when we want to use water. No worry about ever pumping water out somewhere, pump burning out or running down batteries.

[JackConrad]

Mine pulses every half hour or so. I figured I have a leak but so far haven't found one so it must be very small

Another thing that will make a pump pulse is a leaking check valve in the pump.  No water leaks out of the system, just pressure leaking through the check valve.  Jack

[TomCat]

And another thing...that will make a pump cycle, is air in the water lines.

If I let my system get de-pressurized, some air will get locked in it someplace, and if not bled out, will cause the pump to cycle.

Took me over 18 months to figure that one out...

Jay
87 SaftLiner

[WEC4104]

Air in lines causing cycling?  Can somebody school me on this? It goes against what I would expect.

If the fresh water system lines are completely full of water (no air), and there are no leaks, the pump should be able to pressurize the system very quickly, since water is an incompressible fluid. Turn the pump off, and as long as their are no leaks, the system stays pressurized.

Now let's suppose there is a tiny leak.  With virtually no air in the system, it will take very little water loss before the pressure drops enough to cause the pump to cycle. After only the slightest water usage, the pump will run, but very briefly before the pressure is restored.  With no air in the system, the pump should be turning on and off more frequently (cycling).

Now let's look at the situation where the lines contain 10% air.  When the pump runs, the pocket of air gets compressed. This compressed air essentially acts as a "spring", pushing on the water. As some water is used, the compressed air will expand a bit, permitting some amount of water usage before the pressure drops below the point where the pump must cycle.

I would expect that if there is air in the lines, the pump will run for longer time periods (compressing the air). But it should cycle less.  No?  

[DrivingMissLazy]

Air in lines causing cycling?  Can somebody school me on this? It goes against what I would expect.

If the fresh water system lines are completely full of water (no air), and there are no leaks, the pump should be able to pressurize the system very quickly, since water is an incompressible fluid. Turn the pump off, and as long as their are no leaks, the system stays pressurized.

Now let's suppose there is a tiny leak.  With virtually no air in the system, it will take very little water loss before the pressure drops enough to cause the pump to cycle. After only the slightest water usage, the pump will run, but very briefly before the pressure is restored.  With no air in the system, the pump should be turning on and off more frequently (cycling).

Now let's look at the situation where the lines contain 10% air.  When the pump runs, the pocket of air gets compressed. This compressed air essentially as a "spring" pushing on the water. As some water is used, the compressed air will expand a bit, permitting some amount of water usage before the pressure drops below the point where the pump must cycle.

I would expect that if there is air in the lines, the pump will run for longer time periods (compressing the air). But it should cycle less.  No? 

Further to what you state, Camping World sells a device that has a rubber bladder inside. Water pressure is hooked to the device, separate from the bladder. The pressure of the water compresses the air in the bladder.This device significantly reduces cycling and even allows a small amount of water to flow before the water pump kicks in.

Richard

[luvrbus]

Richard, that device is called a accumulator tank works like a bladder tank on a well.I have one on my system and think it was a waste of money for the water on demand pumps and a lot of trouble keeping the right air pressure plus I mounted mine where it is hard to check the air pressure but if anyone wants them JC Whinety has one on sale

[Sean]

We have two 24-volt, electronic sensor type demand water pumps on board Odyssey (one for the fresh water system, and one for the separate drinking water system).  They have both been "on" essentially continuously for the last four years.  We only turn them off, usually briefly, in these circumstances:

• To replace filters on the pressure side of the pump.  One sediment filter for the fresh water, and a sediment/carbon pair for drinking.
• If we accidentally run one of the tanks out of water.  The pump will run continuously if this happens, and we shut it down.
• To effect repairs, such as to our recirculating valves (see below).
• When going away from the bus for more than a couple days, such as when we occasionally take a cruise.

This last item, BTW, is more a matter of conserving battery power while the bus is layed up -- we depend on the 330 watts of solar panels alone to keep the fridge running (and sometimes the bus aired up) -- than any concern about leakage.  The pumps don't draw much current when they're not pumping, but on, say, a month-long trip away from the bus, every milliwatt helps.

For those reasons, there are individual switches for each pump (just one each, and in the bathroom above the sink, for the curious).  Both pumps are fed by the same breaker, which is where we turn them off when laying the bus up for a while (along with all other non-essential circuits).

Few of us, I suspect, turn off the city water pressure to our fixed dwellings (if applicable) when we're not using it, so it puzzles me why people turn off the water pressure in their RV's (not counting unoccupied units, or uninsulated units in freezing conditions).  When I turn on the tap, or the shower, or flush the toilet, I just want it to work every time.

Of course, we don't ever shut our inverter down either, or unplug all those pesky phantom loads.  This is my house -- I want the clock on the microwave to be right (and, actually, the darn thing won't even work unless you set the stupid clock) and the TV to remember what channel it was on. Etc.

BTW, the only thing that has ever "leaked" in the bus has been the cheap-o irrigation valves that we use for our water-saving "instant" hot water system.  When this happens, the water just runs back to the tank, but it will waste all the hot water and make the fresh tank warm.  The flexible diaphragms in these valves tend to accumulate calcium deposits from hard water, and eventually a bit of calcium prevents the diaphragm from sealing completely.  I end up putting new diaphragms in the valves about once every year to 18 months or so, around $6 IIRC.

FWIW, YMMV, HTH, etc., etc.

-Sean
http://ourodyssey.blogspot.com

[jjrbus]

Accumultor tanks are only a waste of time and money if you don't have a problem. I added one after a couple years. Better to plan for one when doing the plumbing than trying to figure out where to put it later!!!