how does a compressed air water tank work?

[Diana Sharp]

 I recently purchased a 1964  16ft Aladdin camper, It's in excellent condition but needs some miscellaneous repairs, It has a compressed air water tank . I need some instructions on how these work- Is there a PSI?

[VK Lee]

The compressed air tank supplies running water due to pressure. The lid and other fittings as well as the hand pump must be fairly air tight in order to work. Hose pressure filling the tank also adds pressure. When the pressure goes down, then it can be re-pressurized by a small tire pump at the tank fill or the hand pump inside the trailer. Pressure should be around 45 to 50 psi as most trailers are designed to run at 45. However, I'm certainly not well versed in vintage air tank systems. Most have copper lines and flare fittings, so it's possible they could handle a lot more pressure than 45. VK

[John "T" Nordhoff]

On the older Winnebago motorhomes, the fresh water holding tank was a closed (held air pressure) galvanized steel tank and used a small copper supply line to an electric (12 VDC) automatic pressure regulated air pump that turned on at say 15 PSI and Off at say 30 PSI. All it did was pump pressurized air into the tank which forced the water out through the water supply lines.

John T

[Diana Sharp]

Thank you for the information. My camper does have the galvanized tank but there is not a regulated air pump. It only has the valve which looks like a bike tire valve. I'm going to get a little pump tomorrow and give it a try.

[John "T" Nordhoff]

If you use an air compressor and pump her up to around 30 PSI (DO NOT put too much pressure !!!) it will force water out ONLY a short time. They make those small 12 VDC air pumps with auto On/Off pressure switches and my best guess is On at maybe 15 PSI and Off at maybe 30 to 35. Its been a while since I saw that air system used in RV's, (and prone to cycling if theres even a small air leak) it may be much easier and cheaper to just use a conventional 12 VDC demand style water pump that has the pressure switch built in and all you do is install them in series in the main water supply with the tanks lower gravity outlet fed direct to their input suction side and their output to thE RV water outlets, water heater inlet etc. PIECE OF CAKE AND UNDER $100............

John T

[Harrold Tuch]

I have a 1963 Nomad and the compreassed air water tank on mine says 75 pounds . The tank is under the front left bench seat. When you lift the seat the tank is accessable but filling up both water and air is done from outside. good luck Harry

[Diana Sharp]

Thank you for the response. I found the tank and filled it up but I only used a hand pump and it worked at 20psi but I was afraid to go higher.  I made it up the Alcan to Alaska but did not use the water tank but I will be doing a leasure trip back to the lower 48  in the summer and am hoping to get it all figured out. 

   Thanks again for the information

[John "T" Nordhoff]

Good to hear, based on what you just posted if it works that well and that easy, heck it may be easiest n cheapest to just buy an original type of 12 VDC automatic RV water system air pump with a regulator (Like the Old Winnebagos used) that pumps up to 30 PSI and shuts itself off then repeats as necessary when the tank pressure drops to around 15 or so. I wouldnt be afraid to use 30 PSI, as I recall thats around where they operated. When I mentioned the in line demand type like most RV's use nowadays, I was afraid of air leaks, but if yours works well with an air pump (not a bunch of air leaks) you may be okay with taking her back to the original factory configuration. Of course, a simple toggle On/Off swich needs to feed the pump so its shut off when your not using the camper. We took an extended trip to 8 National Parks in the West and Pacific Northwest this summer (1995 Chevy Four Winds 26 Ft Class C), maybe the next trip we will do the Alaskan Highway thing, probably when gas is $5.00 grrrrrrrrrrrrrrrr. Headed to Florida after Christmas for Banjo Pickin, Square Dancin, Antique Tractor Shows, and the Tin Can (Vintage RV) Tourist Rally , I hope its warmer then it was last winter brrrrrrrrrrrr

Ol John T in Indiana