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Old 08-11-2003, 12:14 PM   #1
2 Rivet Member
1978 31' Sovereign
Mesa , Arizona
Join Date: Jul 2003
Posts: 37
City Water Valve Assmbly Question


I have a plumbing question to ask…. I have a 1978 31’ International LY.
I am in the midst of replacing some failed water valves in the back of my coach that allow once to drain the freshwater tank. I noticed that there are a series of valves coming in from the city water connection. They appear to be first a water pressure reducer, a water pressure regulator (big cast bonze valve) followed up by a pop valve. All of my friends that have non-airstream trailers have none of this functionality. Their trailers simply have the water pressure reducer built into the city water hookup on their trailer.

When I am hooked up to city water, I attach a pressure reducer to the city water hookup and then attach my hose to it so that I reduce the amount of pressure on my hose connecting my coach with the city water hookup and the coach itself. If I were to install the pressure reducer and the pop valve in the system, is there really a need for all of the other components included in the “stock” airstream configuration from 1978? It seems that it adds quite a bit of complexity to the system. Again, I am thinking of replacing all of this hardware with a pressure reducer and a pop valve that will dump the water onto the ground if it exceeds a given pressure. Would this be a mistake? What functionality would I be leaving out? Should I reinstall all of the old hardware? What purpose does it serve?


Slade Weaver

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Old 08-11-2003, 04:00 PM   #2
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1978 25' Tradewind
Metro Phoenix , Arizona
Join Date: Jun 2003
Posts: 1,439
well, a couple/three things...

Maybe it's just that mine doesn't have it, but I'm wondering about a valve that supposedly allows you to drain the fresh water tank. I'm not real sure that exists on your unit. I'd expect a drain valve to be on the bottom of the tank.

Second, if the valves aren't bad, why bother to replace them?

Third, you will want a check valve in the city water line, so water doesn't shoot out when you turn on the pump.

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Old 08-11-2003, 06:51 PM   #3
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1982 34' Limited
Tidewater , Virginia
Join Date: Dec 2002
Posts: 186
Oh that water thing again!


I posted several weeks ago problems with my water system. No h2o from the city pressure and the pump provided no water as well!

I have the same trailer as you do, '78 31' International, rear twin and center bath. I have also solved my problems and some of this might be of help to you. What is in my system is first, the city water attachment point. Second, is the one-way check valve to prevent pumped water from exiting the rear of the trailer! Next is the Watts pressure regulator (adjustable, came from the factory set at 45psi (mine did anyway)), and finally, an over pressure pop off valve (Watts brand as well). My overpressure valve decal has disintergrated so I can't tell you the pop off pressure. The PO of my trailer never has a screen at the city water entrance or any plug to seal the system. Bugs started to make some sort of nest there and when city water was hooked up the water pushed the nesting material into the interior plumbing. This material eventually was stopped by the one-way valve, eventually causing the city water system to be inoperative.

The PO also seemed to have been using the internal tank and pump to provide his water. When I tried the system pump it turned on and ran ... and ran ... and ran. No H2O to the system. Discovered the water filter/strainer for the water entering the pump was cracked causing the pump to run on as it couldn't develop a vacuum to draw the water. Fixed that and discovered the pump worked fine except for the cracked bottom cover and side case, both of which leaked severly. This was probably due to poor winterization the year prior to my purchase. This was an estate sale so couldn't talk to PO!

I have cleaned up all of the valves, checked the pressure valve and added a whole house filter to the city water system. I have also replaced the original pump with a FloJet VSD pump. It's quiet and provides copious amounts of water (3.7 gpm). This pump requires no accumulator tank and, did I say, it is quiet!!!

The bottom line is with the industrial quality pressure regulator, proper filtration and high quality one way checkvalve the city water system is near bullet proof. Bring on that high pressure park flow!!!

Hope this is of some help,

Take care,

Old trucks and old trailers . . . a comfortable combination!
AIR 1446
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USN Aircraft Maintenance Officer, Ret.
'91 Suburban R-2500 w/BBC
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Old 08-11-2003, 10:38 PM   #4
2 Rivet Member
1978 31' Sovereign
Mesa , Arizona
Join Date: Jul 2003
Posts: 37
Thanks for your comments folks. Sounds like I should leave the rig as is. My city water connection is configured exactly like yours Sean. My pop valve was shot, but I purchased a used one out of a 94 Excella. Looks like it will work so I will put things back as is. Mine is a rear bath model and I noticed that the pressure regulator assembly is not attached to the trailer in any way. I will probably build a bracket to attach it to the aft wall of the coach.


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