Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×

Thread Tools Search this Thread Display Modes
Old 10-19-2014, 10:33 PM   #1
3 Rivet Member
Mantua , Ohio
Join Date: Sep 2014
Posts: 101
New pump and tank questions

I want to change out this old 20 gal Galv. tank for a new 20 to 35gal plastic tank and at the same time put a new pump in.
This might sound stupid, but basically I will just use a compressor to pressurize the tank? The existing pump/compressor appears to be 12 volt, so that I would assume is the ONLY way to go so I can use batteries to have water?
I don't understand how the existing system works as there is only one inlet for water. Or did they just let the tank fill and use that as the pressure?
I think I'd rather put some valves in and just by pass the tank. Would that make any sense, instead of having to fill the tank? How are new units setup?
Thanks for any input!
Attached Thumbnails
Click image for larger version

Name:	DSCN1130.jpg
Views:	114
Size:	286.8 KB
ID:	224732  
Studioman is offline   Reply With Quote
Old 10-19-2014, 10:46 PM   #2
Rivet Master
1974 Argosy 20
2014 20' Flying Cloud
Kooskia , Idaho
Join Date: Jul 2009
Posts: 4,591
I don't know what Airstream model you have, but the old ones which used a galvanized tank and air compressor system worked like this: The tank was filled with water and caped off. The air compressor added air to about 40 psi and that forced the water out of the tank and to the faucets.

Modern systems using a plastic tank are not pressurized that way, it would explode the tank. When you put a plastic tank in, you will change to a demand pump which draws water from the tank (not under pressure) and pressurizes it. When a faucet is opened, the decrease in pressure starts the pump automatically. When the faucet is shut off, the pump has a pressure switch which shuts the pump off. These pumps cost $75 to $150 and operate on 12 volts.

To use city water on the system, you put an inlet hose connection with a check valve into the line between the pump and the faucets. The pump will not allow water to back up into the tank, as it has a one way valve built into it. The check valve on the new city water inlet keeps the water from flowing out of it.

Does that make any sense to you? Hope so. Ask more if you need to.
idroba is offline   Reply With Quote
Old 10-20-2014, 09:01 AM   #3
3 Rivet Member
Mantua , Ohio
Join Date: Sep 2014
Posts: 101
LOTS of sense!
Except where and why the check valve and hose connections go?
Is there one or two "Hose connections"?
Sorry to sound so stupid on this subject. And THANKS for your help!
Studioman is offline   Reply With Quote
Old 10-20-2014, 10:29 AM   #4
Rivet Master
1974 Argosy 20
2014 20' Flying Cloud
Kooskia , Idaho
Join Date: Jul 2009
Posts: 4,591
You will fill your water tank with a connection to the new tank and gravity. The tank connection is usually about 1.5 inches in diameter and the exterior inlet is a plastic part which recesses into the trailer wall and has a cap over the end, and often a little lockable door so it is only accessible by you. They are available at any decent sized RV parts place. They also will have a smaller vent tube nipple which must be connected to the new water tank so it will vent air out as you put the water in. You fill the tank with a hose, but it is not screwed into the new tank inlet, gravity does the job. This is so you don't pressurize the plastic tank, which would break it.

The city water connection usually, but not always, has a check valve built into it. There are several types available, again go to a good sized RV parts place and see which one works best for you. Then look to see that it has a built in check valve. That check valve prevents the new internal pump you install from simply forcing water out the city water inlet. This city water inlet is going to have a 1/2 or 3/4 inch threaded outlet so it can attach directly to the pressurized pipes inside the trailer. It will also have a hose connection on the outside, so a hose can be screwed directly into it running full city water pressure.
idroba is offline   Reply With Quote
Old 10-21-2014, 05:49 PM   #5
3 Rivet Member
kevinkatz's Avatar
1965 17' Caravel
Curtis Wright
San Marcos , Texas
Join Date: Jun 2009
Posts: 231
Images: 38
Send a message via AIM to kevinkatz
related question...
can the pump be put in series or in parallel? does it ruin it to have it in series when using shore water?
kevinkatz is offline   Reply With Quote
Old 10-21-2014, 07:13 PM   #6
Rivet Master
TG Twinkie's Avatar
1974 Argosy 26
Morrill , Nebraska
Join Date: Nov 2009
Posts: 6,013
Images: 2
Blog Entries: 5
The city water should be connected to the plumbing downstream from the pump. In other words, on the discharge side.
It can be connected virtually anywhere in the cold water line.

Sent from my iPod touch using Airstream Forums
TG Twinkie is offline   Reply With Quote
Old 10-21-2014, 09:40 PM   #7
3 Rivet Member
Mantua , Ohio
Join Date: Sep 2014
Posts: 101
I see, I see said the slow guy...
A simple google produced this drawing, which now makes PERFECT sense to me...
So this is what you meant... TWO check-valves... I got it now.
Here is the pic that made me understand in seconds.
Water, Water, Everywhere!
Studioman is offline   Reply With Quote
Old 10-22-2014, 11:54 AM   #8
Rivet Master
1974 Argosy 20
2014 20' Flying Cloud
Kooskia , Idaho
Join Date: Jul 2009
Posts: 4,591
See how smart you can get quick? Google is almost as fun as asking on the Forums, but we like to post too. Thats how you become a rivet master, just post on and on and on ......

Anyway, glad you are up to speed now. We probably didn't slow you down more than a day or two... LOL.
idroba is offline   Reply With Quote
Old 03-11-2015, 12:54 AM   #9
New Member
1973 31' Sovereign
29 Palms , California
Join Date: Mar 2015
Posts: 2
Thanks for the link studioman I have been reading the forum for a few nights looking for this info.
73 Sov 31 is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Water pump & tank questions clicknathan Water Heaters, Filters & Pumps 15 07-14-2018 11:12 AM
Pump doesn't turn off and it doesn't pump water either. I don't know what to do! Melimelo Fresh Water Systems 10 05-25-2018 02:39 PM
Black Tank, Grey Tank, New Tank, Old Tank Bunkroom Waste Systems, Tanks & Totes 3 07-22-2014 09:35 PM
68 water pump-should the pump cycle? Boondocker Water Heaters, Filters & Pumps 8 08-06-2006 11:11 AM
Questions, Questions, Questions LowellN Repairing/Replacing Floor &/or Frame 5 10-28-2004 08:23 PM

Featured Campgrounds

Reviews provided by


This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.

All times are GMT -6. The time now is 06:44 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.