Water hookup question...

depends on your setup...

on mine... even with the water hooked up, the pump still ran and water was pulled from the tank as well as from the city hook up..

from talking to friends it seems that every RV is different,,,,

at least that is what I learned....

Mine has a valve that I can switch from tank water (runs the pump) or off the city water, pressure of what ever is there is what is in the trailer. If I have city water hooked up it won't fill the tank, that is a different inlet. Our old trailer we had there was a automatic type switch..think it had a spring, if the city water was hooked up and pressure was on that side, it pushed the plunger to close off the inlet to the tank..when the city water wasn't on, the spring held the plunger open for the tank-pump to feed the trailer. I always put a pressure valve on when I use city...don't want to blow fittings off the trailers pipes.

On my trailer the two water connections are separate. The city water connection by-passes the holding tank and pump. I'm not sure what would happen if I put water in the holding tank and turned the pump on while still being connected to city water. Not sure if the extra pressure would damage the system or not but I'm not curious enough to try it to find out.

Most have a ONE WAY valve from each leg (tank and City).
Here is a pretty good diagram of how it works...

Your pump should be inline between your fresh tank and the rest of the plumbing. It has built in back flow prevention so that when using city water it doesn't go into your tank.

EDIT: downtheroad beat me to it with a very nice diagram!

Thanks for the great responses (and nice diagram)....but still wondering of what would happen if pump was turned on when city water was present....I guess if there is a backflow valve, then the effect would be the same as when the pump is on but no taps are open, so in other words....nothing would happen as long as there is city water pressure...

limbery wrote:
Thanks for the great responses (and nice diagram)....but still wondering of what would happen if pump was turned on when city water was present....I guess if there is a backflow valve, then the effect would be the same as when the pump is on but no taps are open, so in other words....nothing would happen as long as there is city water pressure...

I used to operate the 12 volt pump at the same time as city water was hooked up. seemed like there was a little better flow.
bumpy

What happens is you get a bit more flow.. Well, at least in my trailer that's what happens... ;)

The check valve in the city water connection keeps you from pumping out water when it's not hooked up to the hose if you turn on the pump.

In the old days, you had to screw in a PLUG to the city water connection to block the water pump flow..

Today, the check valve does that for you..

If you are connected to city water and have the proper pressure valve attached you should only have around 40-45 lbs of pressure to the trailer. That's about all the pump provides too.

If you run 'both', you won't be pumping 90 lbs of pressure thru the system... ;)

It'll still be the 40-45 lbs as always, but you'll be pulling from the tank and the city water too..

Again, at least that's how it works in my trailer... :)

Mitch

limbery wrote:
Thanks for the great responses (and nice diagram)....but still wondering of what would happen if pump was turned on when city water was present....I guess if there is a backflow valve, then the effect would be the same as when the pump is on but no taps are open, so in other words....nothing would happen as long as there is city water pressure...

been there,done that, doesn't cause a problem, but what happens (at least on my trailer) depends on the city water pressure and the pump pressure.

If city water pressure is higher than the pressure that the pump puts out, pump stays off, city water supplies everything.

If city water pressure is lower than pump pressure, then the pump will kick in and also supply water, how much depends on the pressure from each source, line size etc.

In my case, pump pressure is 55psi, so at campgrounds with low pressure the pump runs intermittently if I forget to turn it off and it supplies some water from the fresh tank.

I have a regulator on my city water set to 60psi. However, if you don't regulate inlet pressure and it is much higher than the pump, the pump will likely stay off and you won't notice anything. If the pressures are closer together, or city can't supply high flow, the pump will help make up for the pressure drop and keep the flow up.

The pump backflow valve in theory keeps the city water from backflowing into the fresh tank and overfilling it.

All depends how much pressure is in the city water connection. Low pressure, your pump will turn on and supplement the city water. If you have a good city water connection, your pump shouldn't turn on, unless you maybe open everything up.