New pump VS. Fix the old one

[Globie64]

Hi- we are on to the next step in our Airstream adventure, which is to get the pump and tank water system going. I put in a new fresh water tank and replumbed to it, from it and in between. We have the old type on demand pump, with the motor and a fan belt, and two little pistons that go up and down. It's pretty cheap to get a new pump, but this one goes on and off and seems like it might work, it just doesn't pump. Is there an easy fix (O rings or something) or is it just better to get a new one?

Peter

[Jammer]

The PAR series pumps are still made by ITT Jabsco and service kits including belt, valves, and diaphragm are available for around $100 from marine dealers. I believe most older Airstreams used a PAR 36800 pump but you would want to check and be sure before ordering parts. A google search on "PAR service kit 36800" turns up many online suppliers. You can also get them through Airstream dealers.

The PAR pumps are noisy compared to newer designs but many people believe they are more reliable. My trailer is newer and doesn't have one.

[Randy Gates]

If you just replaced your tank then I would replace it with a modern and quiet water pump. They cost about 90.00. I would feel alot more confident with a new pump to fully pressurize the new tank. Then just check the rest of your systems for leaks or needed repairs. It all depends on what your comfort level is. Happy motoring!
Randy

[dwightdi]

The PAR pump does not pressurize the tank. The old air pumps did. You had to use a metal tank to make them work properly. The Par pump is OK but I chose to replace it with one of the rotary ones when my PAR quit.

[RickDavis]

The shurflo 2088 series pumps are reasonably priced and quite reliable. They are probably quieter than the PAR but noisier than some of the more expensive quiet design pumps.. My observation is the more expensive pumps are not as reliable as the basic shurflo but others may feel differently.. I don't find the pump noise that objectionable.

[Globie64]

Thanks, this is all interesting. I went ahead and bought a new shurflow- it's not a pressurized tank. I replaced most all of the copper with PEX, replaced faucets and with the pump we should be good to go. It all works well with city water, so far.

[C5Don]

Under interest of full disclosre, I am a vendor doing market research of "those in the know", which by my question, am not relative to this issue.

I saw mention of pressurized tanks. Do any RV's actually pressurize the water tank? I am obvioulsy familiar with the small tanks used in typical "home well" pump systems, but didn't think anyone pressurized a large water holding tank. I say this as I would think putting much pressure on the tank would "alter the shape" (to say it mildly) of any plastic holding tank, and even any smaller gauge metal tank. Many have seen the high school physics class demo of filling a 55 gallon drum with an air compressor!

I would greatly appreciate your comments as perhaps we are missing a requirement of a needed version of a tank gauge!

Don

[dwightdi]

Early airstreams used a steel fresh water tank and indeed were over pressurized with air from a small compressor or pumped up at the filling station. This meant that if you had a small leak in the system when you were running down the road the air pressure pushed all the water out through the hole and sometimes inside the trailer. The tanks were heavy and this fail mechanism caused the airstream company to go to pressure on demand water pumps.

[Globie64]

I think I've seen one of those tanks, round with the ends riveted on? The system reminds me of the windshield washer in my 1968 VW Squareback, a pressure tank driven by the air in the spare tire.

[C5Don]

dwightdi,

Thanks for the information. I ask as our system uses a pressure sensor and a "bubble tube" to monitor tank level. I can use a "differential pressure sensor" which means a bubble tube would go to the tank dishcarge line and a "second tube" would then be required to go to the top of the pressureized water tank. Thus the top tank pressure goes to one side of the sensor and the other side goes to the discharge line, where the "difference in pressues" would then allow me to measue the volume of a pressurized tank properly. However, as a market decision, and since it sounds like pressurized tank is an anomoly, it's not worth increasing product cost for everyone whom does NOT need this capability. I didn't think this was common, but being human, thought we might have "missed something". Thank goodness that is not the case! Thanks again for the information.

Don