[Jack Houpe]

I purchased a spare compressor on eBay just in case something ever happens to my Junair oil type compressor. I paid $112 and it was free shipping so it was a no brainier. My unit is 220vac and located where the inverter heat pumps are located in the basement air compartment. After taking it apart to look at all the goodies I seen a lot that I was impressed with, the flywheel is off center to make the compressor almost vibration free and with the rubber feet it seems to be a solid unit. It puts out more cfm than the oil unit but not as quite but after installing the intake filter and putting a line on the output side it got to a pleasant hum but not dead silent. It is very small in size and heavy. For those of you looking for a cheap alternative I would recommend this unit. I think they come in 120v also but more expensive.

[Wanderman]

Jack,
After you told me the model/voltage of your Junair, I went looking around for one. I found lots of the rocking piston ones, including 120V versions... but was unsure if they would be suitable.

[BusNit]

Rick, you have to watch out for maximum pressure developed. Some of the rocking piston compressors are designed for aeration of ponds and are rated at 45-50psi maximum. I decided to use a new California tools long life compressor that puts out a little over 3cfm at 90psi. It fills the aux tank from 65 -100psi in under a minute. The Gast pump took much longer at around 4-5 minutes.

[Wanderman]

The ones I was/am looking at max out at 175PSI (4.4 amps@220 and 8.5ish@120) I have seen the California Tools ones as well. My gast is beginning to leak around the heads, so it's either rebuild or replace.

[hypoxia]

Interesting that the early coach used lower pressures, the 120VAC Thomas pumps on the later coaches bring the tank pressure to 125 psi. I would surely like a silent Jun-air.

[Jack Houpe]

This one it 8 bar 117 psi roughly, I think the oil type is good for 144 psi, either is plenty.

[Wanderman]

I just ordered a Jun Air OF332. See pics below. Now to figure out what plumbing and electrical i need to changeout/modify to replace the existing GAST. Thread size/pitc...Metric or SAE? Do I need a check valve to prevent the engine compressor from keeping pressure on the head, etc etc.

Won't really know until it arrives and can be measured. Unless someone already knows that is!

[Jack Houpe]

That should do the job. That will put out almost 180 lb of pressure make sure you have your pressure relief valve set about 120 lbs.

[Wanderman]

Most definitely Jack!

[BusNit]

Yes on the check valve. It takes some pressure off the compressor and avoids bleed down, keeps the engine air brought up to 110psi and helps the aux compressor to start under load although that load should have been released at the air pressure cut-in/out switch. On my coach if I plug in to shop air, say around 120psi, the aux compressor cut-in switch will bleed out anything over 100psi. At first I thought I had another air leak but it was just doing its job. On the new compressor install, I put in a 1/4" high temp flex lead that about 12 or 18" to go from compressor to auto-drain water separator. I figured the hot air from the compressor head might deteriorate anything else used unless it's hard pipe. My new Gast developed leaks around the head so I gave up on it. Was an expensive affair as I thought Gast was the best in the business. If the California compressor lasts at least 3 years, then it's a cheap bargain and easy to swap out. (California Tools MP100LF) Mine runs on 120v and I didn't want to exceed the original amperage of the coach's wiring of 7 amps.