Need diagram explained please

[Bex]

This is our first trailer and I am still trying to understand how things work, please be patient if this is a basic question, its not basic for me
I found this diagram elsewhere on the forums and I am a little confused.
Why is the city water terminated in a tee that goes to the toilet and also the pump, and the water heater, should it not go directly to the pump? Why does it end in a tee?
Is it because its under its own pressure?
So when using the tank only the pump is energised for water pressure?
Can someone point me to the reasons or explain why it is this way if that is not the reason.
Is the water that goes through the heater pressured?
Our trailer is not this configuration but I presume the principles are the same
Thanks in advance

Bex

[drag'nwagon]

Bex,

Short and sweet, it is really two water systems in one (kind of). There is a check valve at the water pump so that when connected to city water you do not "back fill" the FW tank. Likewise, there is a check valve at the city water connection so that when running the pump you don't shoot the water out of the city connection. The cold water into the water heater does infact pressurize the hot water as well as the rest of system. Typically the entire system is regulated at 40psi.

[Olielulu]

let's see if I can explain without making it more confusing.

The city water inlet and the pump discharge tee into the same line so that you can run off either one without having to have completely seperate piping systems. The city water does not provide water to the pump. The pump gets its water from the water tank. Everything after the water pump discharge is pressurized, including the hot water tank.


Good luck and have fun,
Mike

[Bex]

Thanks Guys, I really appreciate your input.
I am trying to understand what you have written in relation to the two diagrams and cannot.
What you have said makes sense but I am a very "visual" person and need to be able to "see" it before doing it, and I am just not seeing it in the diagram. Looks to me like the diagram has a line missing, the one that feeds to the outlets or, the actual City water to the pump. Surely the line in and out to the outlets cannot be the same? Am I making sense?

Bex
My carpet cleaning units are complex, but I can fix them, this is "doing my head in"

[azflycaster]

When connected to city water the pump is not used and is turned off. The city water pressurizes the system and feeds water to all the outlets including the water heater.

[Bex]

Go it.
Now just one last item I think, then I can re-build my plumbing.
Why (in the diagram) is there a line joining the tank to the city/main line?

Bex

[Journalist]

Your confusion is stemming from the fact that you are assuming the city water "feeds" the pump. It doesn't. The tank does. The pump serves the same purpose as the city water inlet. They both provide pressurized water to the system.

[Journalist]

Originally Posted by Bex

Go it.
Now just one last item I think, then I can re-build my plumbing.
Why (in the diagram) is there a line joining the tank to the city/main line?

Bex

That's a bypass valve to allow the tank to drain past the pump through the main drain valves.

[Bex]

Originally Posted by Journalist

Your confusion is stemming from the fact that you are assuming the city water "feeds" the pump. It doesn't. The tank does. The pump serves the same purpose as the city water inlet. They both provide pressurized water to the system.

You are quite right about that. I "got it" just a few minutes ago and your post confirmed.
My thank and appreciation!!

Bex

[Bex]

Originally Posted by Journalist

That's a bypass valve to allow the tank to drain past the pump through the main drain valves.

Thank you for your help.
I asked in another post about line size but I will ask here as well.
Ideal line sizes from the inlet around the trailer?
to the outlets?
From the tank to the pump?

Bex

[wmarsha]

ideal is the catch, here. 3/8 line is what most rv's use. the pressure and flow is less than what we expect in our stick houses. bigger in an rv is not better. you will have a harder time building pressure, and will "waste" water more easily.
I have seen some 1/2 inch stuff, tho usually rigid copper-too stiff, too hard to work with. Use PEX.
best of luck
ol' bill

[Distantdrummer]

Bex how bout a link to where the diagram came from here on the forums,(URL would do).
Also what is the diagram out of (service manual ? what year & models)?

General questions:
What would happen if the water pump was turned on while city inlet was also in use?

How does the (valved) bipass line around the water pump (and check valve) help drain a water tank that is under the floor (as opposed to the pictured above floor variety)?
~~or~~
is it there as another way to fill the water tank,(with "city water") eliminating need for manual pour in. ....not to drain the tank? ~~or~~ would it serve both purposes (filling and draining) ?

[Bex]

http://www.airforums.com/forums/f443...ram-63891.html

This is it.
Bex

[Bex]

Originally Posted by Distantdrummer

is it there as another way to fill the water tank,(with "city water") eliminating need for manual pour in. ....not to drain the tank? ~~or~~ would it serve both purposes (filling and draining) ?

I thought that might be the case, but I would bow to others knowledge and expertise here.

Should I be making the city water (and tank to pump) line 1/2 or 3/8 inch then tee 1/4 inch to the outlets?

Bex

[Shacksman]

Originally Posted by Distantdrummer

General questions:
What would happen if the water pump was turned on while city inlet was also in use?
The city water pressure is usually higher then the pump pressure and will keep the pump from coming on.

How does the (valved) bipass line around the water pump (and check valve) help drain a water tank that is under the floor (as opposed to the pictured above floor variety)?
~~or~~
is it there as another way to fill the water tank,(with "city water") eliminating need for manual pour in. ....not to drain the tank? ~~or~~ would it serve both purposes (filling and draining) ?
If you put a "T" in the in and out line from the pump and a line with a tap across them you can fill the tank by opening the tap.

I use this in my trailers.

[mimiandrews]

Originally Posted by Bex

Go it.
Now just one last item I think, then I can re-build my plumbing.
Why (in the diagram) is there a line joining the tank to the city/main line?

Bex

In our trailer ('66 Safari) the "bypass" around the pump allows the tank to be filled from city water, not drained. In your diagram, there's a separate drain for the water tank itself. There should be other drains for the rest of the system.

If the pump were turned on while city water was connected to the trailer, it would turn itself off. There is a pressure switch in the pump that tells it to run only when the pressure in the system drops below a certain level, which should be well below the pressure supplied by city water.

We used color coded 1/2" PEX with crimped fittings to replace the copper water lines in our trailer. Only problem is finding space to operate the crimp tool. In essence, we built each section as much as possible outside the trailer, then laid the assembly in place and connected it at a location where there was room for the tool to operate.

Be sure to draw a diagram (rough sketch OK) of the system you have before you tear anything out. There will be a little re-design necessary, because copper fittings will turn tighter corners than PEX fittings will. Just use the space you have and make something up that does the same job. This was especially true in the area near our water pump.

[Bex]

Pex is what I intend to use and the water bypass is a good idea that (now I know that's what it is) I shall incorporate into the build.
The pump shut off is the same as my truck demand pumps, quits when back pressure gets up.
I do have an ongoing, changing diagram that I am putting together that is now just about complete. Next is to replace the floor, install a new Town water inlet, power inlet and get to work on this plumbing. I might actually have this trailer able to be used before the end of July. OK then, August.
Thats once again everybody for your invaluable help.

Bex