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Replacing auxiliary compressor
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This is not intended to insult new buyers or their skills, but just to point out for first time buyers of a Prevost I am almost certain that unless they actively read and participate on a site such as PC, the purchase of a coach will be so overwhelming few if any would ever give a great deal of thought to the pneumatic systems.
That is probably one example of why buyers need to methodically develop a detailed list of things to inspect or have inspected prior to a purchase. There are many other things that need attention, and since the bus is usually so intimidating and the seller is only likely to talk about things that he knows work, or will add to the confusion a buyer really needs to step back from worrying about getting HD tv or the color of the sofa, and become a methodical inspector.
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Al:
Could I suggest that you put a coil of copper tubing (about 5 turns) before your water seperator? As it sits now, I believe that the air will still be rather warm from being compressed and will carry the ‘humidity’ past the water seperator and into your tank, where it will cool and condense. I cannot tell the size of tubing you are using from the photos, but it appears to be 3/8 inch. You can make a 6 or 8 inch diameter coil by s l o w l y bending the tubing around a piece of 6 or 8 inch PVC pipe or other pipe. Going very, very slow you can usually keep the tubing from crushing. Or, you can do like they bend the u-turns in trumpets and trombones by filling the tubing with water and placing in the deep freeze for 24 hours, then bend the tubing around the mandrill. Lots of cracking sounds, but the ice prevents the tubing from crushing. I also put 3 plastic wire ties equa-distant around each coil and that maintains a small air seperation between the coils to prevent contact heat transfer, plus maintains better cooling due to ambient air circulation.
I will give you an “A” for your design, but if you want that “A+”, install a compressor aftercooler prior to your water trap.
Wishing you smooth rolling.
Fred
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I recently used an air tool on the quick disconnect I added to the manifold I added to the convertor side in the steering bay. I was alarmed that when I disconnected the air hose there was noticeable water vapor spry from the hose! This means there is some moisture in my air system.
My bus is serviced regularly at Jeff’s, and he reported all air tanks dry at a service earlier this month. Air dryer cartridge is replaced annually. Never any water from the trap in the steering bay. So I am confident the water is entering via the auxiliary compressor . Royale used the Jun-Air compressors. They have a two-stage system to trap any oil, but I have not seen a moisture trap.
I would like to limit this moisture to the extent possible. I am thinking a copper coil as mentioned above, and a trap similar to the OEM trap in the steering bay. Any other ideas?
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You nailed it John. Until the water cools it is a dry vapor so it ends up condensing quite a ways downstream from the compressor unless you force it, such as adding a heat exchanger, which is a copper coil.
A simple water trap or a spitter will capture the water and if it is drained regularly you will not pass water into the aux air system.
That demonstrates just how effective our coach air dryers are. Like you I get nothing from my air tanks, but our aux compressors which do not have that quality dryer do make a lot of moisture, which fortunately does get trapped. A lot of folks have stored coaches with the aux compressor powered up to maintain slide seals or for other purposes, only to find excessive water has migrated through the aux air system as a result. They do have to be drained routinely.
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BA,
We have the same system, turn that yellow valve and you merge Prevost aux air with the Marathon side. I like the way Marathon does it. I don’t care if I have a small Prevost aux air leak, it’s isolated and has no effect on the Marathon side as long as the yellow valve is closed. My Prevost aux air leaks down in a couple days, but I don’t need it for anything until it’s time to go again.
This would be a whole lot easier under the awning….
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I got mine hooked to a electic air solenoid valve, it ties the two systems together when I turn the key switch on
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Hey BA, I give you triple A +, nice job….
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I installed the same viair a couple of years ago. The supplied check valve will leak. I replaced it with a bendix dot rated check valve.
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Looks good buddy great job !!!!
Tradewinds Coach
Kyle Bennett (Service)
Brian Miller (Sales)
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