Plumbing question - seeking advice

[Steve_N_Janna]

After a good 18 months I'm getting ready to reinstall the plumbing in my Scamp. I made a diagram when I stripped everything out - but believe it or not it got water damaged (ha!).

The set up includes a fresh water tank with a Shurflo pump and the usual city water hook-up. So I thought I'd install a shut off valve downstream of the pump, isolating it and the tank from the city water. I'd then install a second one in line with the external hook-up.

Nosing around a bit, I've noticed that the shut off valve - or sometimes a one way valve - for the on board water is set up between the tank and the pump. (I'm pretty sure there were no valves at all in my original set-up.)

Seems like this arrangement unnecessarily subjects the pump to the campground water pressure. Is there a reason I should leave the pump open to the city water plumbing circuit?

Thanks for your thoughts on this.

[glamourpets]

What if you were to add a backflow preventer in there past the pump? With the appropriate placement of a T you can prevent city water pressure from reaching the pump.

Disclaimer: I too am pondering a water system. My suggestion is purely theoretical.

[Frederick L. Simson]

We tend to leave our Dinette made up as a Bed 24/7. This leaves the water tank and pump, and any valves in that area under the bench pretty much inaccessible. The shut-off valve between the tank and the pump is to facilitate pump repairs when the tank is full, so you don't have to empty the tank first. Otherwise it stays open. The "City Water" connection joins the main water line between the pump and the water heater, putting the pressure on the pump backwards of pumped flow, which the pump is designed to withstand, making a shut-off valve there unnecessary.

[Steve_N_Janna]

Frederick, thanks for explaining this.

I've not had prior experience with this sort of system & had the mistaken impression that the city water might back flow through the pump and fill the tank - or damage the pump seals due to the higher pressures.

[GMike A]

Im not sure if I asked this before but does anyone have a "schematic" pictoral of a water system? I will be plumbing mine up too and want to at least see my options with pumps,valves etc. I'm like Steve I dont want to subject the pump to city water but I dont want to have a separate input for city if I dont have to. So if I can learn from Steve's experiences that is a good thing.
Thanks

[rabbit]

RV Water System Diagram

[Donna D.]

If I was replumbing my trailer, and I'm not, I'd definitely add Hepvo valves in place of "P" traps. I think it would be beneficial to not have those old traps hanging down below the frame...

[GMike A]

Yep Hep is the only way to go. Thanks Jack for the diagram. IMO there should be a check valve one way on the output side of the pump which is not shown.

However I am using this as a guideline only and can build on it.
danka

[Frederick L. Simson]

Originally Posted by GMike A

IMO there should be a check valve one way on the output side of the pump which is not shown.

Classic Series Water Pump - SHURflo
According to the link above that would be redundant.

SHURflo® Fresh Water pumps include a built-in check valve to prevent back flow into the tank.

[GMike A]

There you go. My idea to patent and they went ahead and put it inside the pump. Happens to all of my great ideas.!!!!!!

[Carol H]

If you go to the documents center on the home page of this site and check the manual for a Scamp it includes the water layout diagram.

No valve on mine between the tank and water pump but I can see as Frederick pointed out it would me handy to have if you for some reason needed to fix the pump and leave the tank full of water. Just not sure how often one can expect to actually need to do that.

I do have bypass valves on my hotwater tank - to prevent it from filling whether on City water or the water tank - that is a feature I use often.

I dont know what having a valve between the pump and the city inlet would achieve. When connected to city water the pump is not in use or turned on (the water pressure from the city connection is all that is needed) and the pump itself prevents the water from filling into the tank. My feeling is the fewer valves/connection points you have unless really needed means fewer places for a possible future leak.

[Jared J]

Originally Posted by GMike A

Im not sure if I asked this before but does anyone have a "schematic" pictoral of a water system? I will be plumbing mine up too and want to at least see my options with pumps,valves etc. I'm like Steve I dont want to subject the pump to city water but I dont want to have a separate input for city if I dont have to. So if I can learn from Steve's experiences that is a good thing.
Thanks

Here's mine. The one mistake is that the fresh water fill for the tanks should be taken after the filter. However, mine work fine off the gravity filler (I wasn't sure it would due to little height difference), so I never added that, anyway.

[glamourpets]

Originally Posted by Carol H

If you go to the documents center on the home page of this site and check the manual for a Scamp it includes the water layout diagram.

No valve on mine between the tank and water pump but I can see as Frederick pointed out it would me handy to have if you for some reason needed to fix the pump and leave the tank full of water. Just not sure how often one can expect to actually need to do that.

I can think of a few reasons that this would be helpful.

These pumps have a rubber wheel - an impeller - that does wear out over time. We use a similar pump in our grooming trucks. In commercial use, they will wear out faster, as the lifespan depends on how much you actually use the pump. Replacing the pump impeller amounts to removing 4 screws and pulling out the worn part.

I think I would want that valve as close to the tank as possible. If you get a leak you can just shut it off and do the repair later. Otherwise you are going to have the whole tank leaking out onto the floor over time. Rather than waste your vacation doing plumbing, just shut off the water and fix it when you get home. That valve makes an emergency plumbing situation into a minor inconvenience.

It also makes the repair easier as you don't have water dribbling into the repair area.

Derek

[Jared J]

Or you can just dump the tanks.

[Carol H]

Derek you right the pumps do need repairs from time to time but the question is how frequently. I can see if the pump was running daily such as the one you use in your biz but most RV water pumps get much less use. Mine hasnt had a failure (touch wood) in six years camping 100 to 130 days a year - of which about 50% is using water via the pump rather than city water.

Second point to ponder is just how often would the situation arise that you need to repair the pump but cant empty out the tank.... the standard Scamp tanks have drain valves attached to the tank right beside where the pump is and the water drains to the outside down through the connection in the floor. I suppose to keep down the number of valve connections/leak points one could replace that valve with a three way one if there is such a thing