Water Inlet ID

[r___r]

What is the reason for the threaded water inlet (B)? Is it just an option, or, is there an advantage for it's use?
I've attached a picture and diagram for reference.







Back Story:
Since I've had this trailer, I had always attached the campground water to threaded water inlet (A). I have used the gravity fill inlet to fill the fresh water tank and used the water pump to pressurize the RV water lines, on a couple of trips. I never hooked up threaded water inlet (B). I was curious what it was for, but, not enough to look into until now.
Lately, I saw videos about a black tank water inlet and wondered if that is what threaded water inlet (B) was for and if this was an option in a 1989 RV. I traced out the threaded water inlets.
Gravity fill hose plumbs into the side wall, upper section of the fresh water tank. Threaded water inlet (A) plumbs into a T-connector just before the water pump and after a clear inline item (Backflow Preventer?) connected to a hose from the fresh water tank. Threaded water inlet (B) plumbs into the side of the fresh water tank, towards the floor.

[Old-Biscuit]

Gravity fill port...pour water into port or sticking hose in it to add water to tank

'A' ...city water inlet connection to supply water to RV plumbing
**your diagram shows it connected to suction side of pump and would then have to go THRU the pump to fed RV Plumbing
City water should connect to cold water line discharge side of pump.

'B' Pressurized FILL for connecting a hose and adding water to tank
*Small cock valve next to 'B' would be drain


NO 1989 Vintage would not have Black tank Flush System unless previous owner installed aftermarket which is NOT shown in your picture

[r___r]

Originally Posted by Old-Biscuit

Gravity fill port...pour water into port or sticking hose in it to add water to tank

Yes it is, I have used it to fill the fresh water tank before.

Originally Posted by Old-Biscuit

*Small cock valve next to 'B' would be drain

Yes, I have used it to drain the fresh water tank before.

Originally Posted by Old-Biscuit

'A' ...city water inlet connection to supply water to RV plumbing

Yes, this is the one I hook up to at the campgrounds.

Originally Posted by Old-Biscuit

**your diagram shows it connected to suction side of pump and would then have to go THRU the pump to fed RV Plumbing
City water should connect to cold water line discharge side of pump

Yes, it is tied in to the suction side of the water pump.
Here's a picture underneath the couch.



I discovered that when I traced the lines out and was curious whether it was hooked up correctly because it was on the input, instead of the output of the water pump. I can move these to the correct side if that is how it is supposed to be.

Originally Posted by Old-Biscuit

'B' Pressurized FILL for connecting a hose and adding water to tank

Yes it is, but is this just an option, or, is there an advantage over the gravity fill?

[GypsyR]

The clear thing looks suspiciously like a check valve that would keep your city water from filling the tank.

I also find it odd for the city water to be on that side of the pump. However it looks like it would be a bit of a pain to change around. Not sure it's worth it. And you know that old saying, if it ain't broke...

[Argosy]

Hook water to B and listen, it will be easy to hear if it's a tank flush. My 93 has a factory installed one so they were available in the general era.

The clear part looks like a water filter.

Do you have a drain port on the tank? You haven't mentioned that. If not, how about this:

A inlet goes to 2 on the tank. The line off the T between the pump and filter/back flow preventer is the fresh water drain.

[Ljwt330]

Like others, I have not seen fresh water plumbing like that, however, there is no reason why it shouldn't work.



The only thing not visible in your photos is the line connection to the petcock. That has to be the tank drain, but it's not clear how it is connected. Given its location, it must share the line from hose port "B" into the tank, near the bottom.


So it appears your are correct. "A" is your city water which has to pass through the pump to pressurize the lines. The clear object is a filter/check valve that prevents back flow into the fresh tank.


"B" port is the tank fill and it must have a check valve in the hose connection. The petcock is the tank drain and must T into the tank fill line somewhere upstream from the hose connector check valve.

[r___r]

Originally Posted by GypsyR

The clear thing looks suspiciously like a check valve that would keep your city water from filling the tank.

Originally Posted by Ljwt330

The clear object is a filter/check valve that prevents back flow into the fresh tank.

Yes, I too was guessing the clear check valve was preventing water to backflow into tank. Thanks for the confirmation.

Originally Posted by GypsyR

I also find it odd for the city water to be on that side of the pump. However it looks like it would be a bit of a pain to change around. Not sure it's worth it. And you know that old saying, if it ain't broke...

Originally Posted by Ljwt330

Like others, I have not seen fresh water plumbing like that, however, there is no reason why it shouldn't work.

Odd yes...I was wondering why pressurized water would feed the suction side of the pump. It has been plumbed in this way since I bought the trailer 8 years, ago.
Unless...through other's experience where the pressurized water has damaged the water pump, I can change it to the other side. I'm looking for other's experiences and opinion on this.

Originally Posted by Argosy

Do you have a drain port on the tank? You haven't mentioned that.

Yes, the drain port is the petcock that Old Bisquit had mentioned in his post and is in the picture in my first post.

Originally Posted by Argosy

Hook water to B and listen, it will be easy to hear if it's a tank flush. My 93 has a factory installed one so they were available in the general era.
The clear part looks like a water filter.
A inlet goes to 2 on the tank. The line off the T between the pump and filter/back flow preventer is the fresh water drain.

Originally Posted by Ljwt330

The only thing not visible in your photos is the line connection to the petcock. That has to be the tank drain, but it's not clear how it is connected. Given its location, it must share the line from hose port "B" into the tank, near the bottom.
So it appears your are correct. "A" is your city water which has to pass through the pump to pressurize the lines. The clear object is a filter/check valve that prevents back flow into the fresh tank.
"B" port is the tank fill and it must have a check valve in the hose connection. The petcock is the tank drain and must T into the tank fill line somewhere upstream from the hose connector check valve.

After both of your posts, I had to review the picture of the plumbing under the couch and my original diagram. my diagram was intentioned to be just a crude visual of the routing. Looking at the diagram again, I can see how it can be confusing to the picture of the outside of the RV, so I re-did the diagram to the actual layout to match both pictures.

[Argosy]

Not counting gravity fill how many hoses are hooked to the freshwater tank?


Did you hook a hose to the B inlet to see what happens?


https://yourfulltimervliving.com/rv-resources/rv-water-pump-troubleshooting-clean-the-screen

[Ljwt330]

Water inlet “B” is probably to pump water through the system from an outside container. Can also be used with a container of antifreeze mix to winterize the system.

[GypsyR]

My only concern with the pressurized water going through the pump would be that the pump might offer a restriction that would negatively affect your water pressure inside the coach when on city water. If the pressure seems to to flow happily on through, no worries. If at some point the pump needs to be replaced and the replacement doesn't allow such flow because of a slightly different design, then that could be a problem. Reaching a bit there though. I'm sticking with the "If it ain't broke" thing.

[r___r]

Originally Posted by Argosy

Not counting gravity fill how many hoses are hooked to the freshwater tank?


Did you hook a hose to the B inlet to see what happens?


https://yourfulltimervliving.com/rv-resources/rv-water-pump-troubleshooting-clean-the-screen

2 hoses. No I haven't hooked it up to a garden hose yet.

Originally Posted by Ljwt330

Water inlet “B” is probably to pump water through the system from an outside container. Can also be used with a container of antifreeze mix to winterize the system.

Aaah...I see.

Originally Posted by GypsyR

My only concern with the pressurized water going through the pump would be that the pump might offer a restriction that would negatively affect your water pressure inside the coach when on city water. If the pressure seems to to flow happily on through, no worries. If at some point the pump needs to be replaced and the replacement doesn't allow such flow because of a slightly different design, then that could be a problem. Reaching a bit there though. I'm sticking with the "If it ain't broke" thing.

Good info. Water pressure seems good inside, I use a regulator outside at the tap. Yeah, I most likely won't change the configuration unless info confirms I should.

[Ljwt330]

Originally Posted by r___r

2 hoses. No I haven't hooked it up to a garden hose yet.

Aaah...I see.

Good info. Water pressure seems good inside, I use a regulator outside at the tap. Yeah, I most likely won't change the configuration unless info confirms I should.

My understanding of your updated diagram and photo is that city water from port "A", enters through the grey poly lines in the photo and is plumbed directly into the system. It does not pass through the pump under pressure.

The line from port "B" is the one that Ts in before the pump.


Is this correct? If so, the plumbing is essentially typical of an RV and needs no modification.

[Argosy]

Originally Posted by Ljwt330

It does not pass through the pump under pressure.

Is this correct? If so, the plumbing is essentially typical of an RV and needs no modification.

Ditto. You flipped A & B from your original post.

The clear part is a filter/screen, not a back flow preventer. I posted a link with pictures of the new and old styles in a previous post. As you have an 89 it is the old style. Probably a good time to clean it.

[GypsyR]

Well when you changed it, it made more sense. Now we can assume the pump does not allow flow past it when you are using the pressurized tank fill B.
Now the filter bugs me though. A filter ahead of most any pump is a good idea as they generally don't like debris. But if you introduced debris through B when tank filling the not-a-checkvalve screen would catch it. But as soon as you turned to pump on it would then draw the debris back out of the screen and digest it.
I guess the thinking is you're a lot more likely to introduce acorns, insects, gravel, or whatever through the gravity fill than city water. Still odd that they wouldn't move it upstream one more slot and that way catch anything from all the incoming water there. You can ensure it never being a problem just by using a filter on the hose when you fill the city water. Which is what I always do anyway.

Should there be any debris in your freshwater hose or the city water? No. But there wasn't supposed to be a dead mouse inside the funnel I use to put oil in the engine either. If our water supply was always perfect all the way through we wouldn't ever need filters.