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Question on air system - filling the air tanks with my shop compressor

Has anyone else added an air connector and valve so you can pressurize the wet tank and brake tanks utilizing your shop air compressor?  My idea is to add a pipe tee just after the solenoid valve which is activated by the "Air Tank" switch.  And at the pipe tee connect a shut off valve and male M-style connector.  This would allow me to use my large shop compressor to air up the wet tank without running the onboard 12 volt compressor or starting the diesel engine.  You may wonder why I want to do this.  Here in central Iowa its COLD this time of year.  From when we start getting snow, usually October until March or May it's maintenance season for me.  We have a heated garage for the motorhome which is next to my work shop and I usually have a list of projects to work on all winter.

Are there any potential problems with airing up the system this way?

Ron Brestel
2004 U-295 with 2 slides 38 foot
Ron Brestel
2004 U295 38' PBDS

Re: Question on air system - filling the air tanks with my shop compressor

Reply #1 –
I would recommend you have an air dryer between the shop compressor and the wet tank. 

Limit the shop compressor output to 120 psi

Otherwise, no problem.
1998 U320 40'
2005 GMC Yukon
MC# 17609

Re: Question on air system - filling the air tanks with my shop compressor

Reply #2 –
The wet tank can be filled using the tire inflator hose and an adapter between the shop hose and tire hose.
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: Question on air system - filling the air tanks with my shop compressor

Reply #3 –
You need to look at your air system diagram no matter what year you have. Connecting an air compressor connection to the aux air fitting will only add air to the leveling system but not to the wet tank or service tanks.

Add an air connection just ahead of the air dryer to fill the wet tank, service tanks and provide air to the level system while using the air dryer you already have.  The air dryer will be more effective (the heater comes on) if the ignition is on.

External Compressor Connection to Add Air to Wet Tank and Service Tanks

An 02-03 U320 air schematic is attached.  Your 04 should be similar.  Hooking up an air line to the aux connection will not add air to the wet or service tanks if your check valves and pressure protection valves are working correctly.  (Not always the case)

Adding a T and a connection after the solenoid that opens the line to the service tank will bypass the air/water separator, filters and desiccant dryer.  If you do it this way be sure to use a water separator, a filter and a drier for your air supply.

If you are connecting an external compressor to the aux air to use the level system you should also be sure to use a water separator, a filter and a drier for your air supply.

Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Question on air system - filling the air tanks with my shop compressor

Reply #4 –
This post got me thinking because I want to use my portable compressor to fill the coach air tanks to search for leaks too.  I like the idea of adding a connection to the drier inlet and will consider that as a future project.
 
The air schematic and on our 1997 U320 show the aux connection is piped directly to the wet tank.  Until there is an opportunity route it through the drier, I will add a separator/drier to the compressor.

Where are the check valves?  Are they at the service tank inlets and marked with an "I"?
40ft 1997 U320

Re: Question on air system - filling the air tanks with my shop compressor

Reply #5 –
Quote from: DayDreamer –
Where are the check valves?  Are they at the service tank inlets and marked with an "I"?

Yes

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Question on air system - filling the air tanks with my shop compressor

Reply #6 –

Those marked U are two way check valves.  Those marked H are pressure protection valves, pressure limiting check valve. There is a another unmarked check valve over near the compressor.

In this case line 5 from the aux air fitting connects to the wet tank.

An air filter is important too when adding air.

Here is a 10 micron filter/water separator. 3/8"  PneumaticPlus SAF3000M-N03BD Compressed Air Particulate Filter, 3/8" Pipe...

Or just a 5 micron filter 1/4" PneumaticPlus PPF2-N02B Miniature Compressed Air Particulate Filter 1/4" NPT...

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Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Question on air system - filling the air tanks with my shop compressor

Reply #7 –
We're dry as a bone down here in the Arizona SW, so I'm not concerned about moisture; I'm going to try today to get air from my aux. compressor into the  coach system; always wondered if there's a check valve, will let you all know. I don't have bags, but it would be nice to have the Hadleys juiced-up in case any of you pull in!  ^.^d
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'

Re: Question on air system - filling the air tanks with my shop compressor

Reply #8 –
Quote from: Roger & Susan in Home2 –
Those marked U are two way check valves.  Those marked H are pressure protection valves, pressure limiting check valve. There is a another unmarked check valve over near the compressor.

In this case line 5 from the aux air fitting connects to the wet tank.


Thanks Roger for the recommendations.

I am guessing the "I" check valves between the wet tank and service tanks are not working because when I open wet tank drain valve, both of the service tanks drain too.  Anybody have part numbers for them?  Is it KN23000?

I have already replaced one of the pressure protection valves, but purchased two of them assuming the other is not far behind.
40ft 1997 U320

Re: Question on air system - filling the air tanks with my shop compressor

Reply #9 –
Ron I Actually have always thought adding outside air has lots of benefits. Primarily I can troubleshoot with no background noise to help find leaks and internal bypassing. My shop air compressor is behind my building and very quiet by design. Hate listening to a compressor run all day long.  Only time I hear it is if I'm using the sand blast cabinet.
The other side of doing it it has to be very sanitary with no possible way to fail. I use a hi-pressure strut servicing valve with manual closure with a internal schrader valve and a brass hi pressure valve cap. Fitted between air compressor and dryer.
Scott

Re: Question on air system - filling the air tanks with my shop compressor

Reply #10 –

The one way check valves on Tanks are KN230000

Amazon.com: Haldex KN23000 Check Valve: Automotive

The inline check valves on lines for the HWH compressor are Haldex (Midland) KN23080

Not sure what the two way valves are.  Call Foretravel

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Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Question on air system - filling the air tanks with my shop compressor

Reply #11 –
Quote from: Roger & Susan in Home2 –
Not sure what the two way valves are.
The 2-way valves are called "Shuttle Valves".  I gave a detailed explanation of their function in my thread about overhauling my air tanks.
See below (Reply #4):

Air Tank Valves R&R
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Question on air system - filling the air tanks with my shop compressor

Reply #12 –
 
Been looking for an appropriate air filter and oil/water separator to use when filling the coach tanks with a shop compressor.
 
I will use an oil free compressor, so not really worried about oil, but air is definitely wet.  Growing up, we had a separator at the outlet of the compressor and that is what I had planned to do, but read a comment by a reviewer stating separators are not effective unless the air has time to cool so the water can condense.  Seems rationale so did additional research and it certainly appears separators only remove condensed water, not water vapor.  An air drier such as the desiccant on the coach system can be used to absorb water vapor, so best route would be adopting one of the posted ideas on routing it through the coach's Pure Air Plus.  Short of doing that,  for a separator to work, the air has to be cooled first.  From a practical standpoint, this probably means putting the separator at the end of the hose vs at the compressor to make it more effective. 
 
Am I on the wrong track? 
 
On another thought, what is the air source for the engine mounted compressor?  Does it use filtered engine intake air or is it filtered at all?
40ft 1997 U320

Re: Question on air system - filling the air tanks with my shop compressor

Reply #13 –
Quote from: DayDreamer –
...what is the air source for the engine mounted compressor?  Does it use filtered engine intake air or is it filtered at all?
On our C8.3 the engine air pump receives its intake air from the side of the cylinder head.  The air is, therefore, filtered (by engine air filter) then compressed (by turbo) then cooled (by CAC).
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Question on air system - filling the air tanks with my shop compressor

Reply #14 –
Quote from: DayDreamer –
Growing up, we had a separator at the outlet of the compressor and that is what I had planned to do, but read a comment by a reviewer stating separators are not effective unless the air has time to cool so the water can condense.  Seems rationale so did additional research and it certainly appears separators only remove condensed water, not water vapor.  For a separator to work, the air has to be cooled first. 
 
Am I on the wrong track? 
No, you are not wrong in your conclusion.  IMHO

Some of us on this Forum have played around with various ways of mounting a 110V air compressor permanently in the coach.  The advantages are IOTTMCO.  I, like you, decided that if I wanted to employ a water filter it would work better at the end of a long pipe.  The thread linked below shows what I came up with.  It seems to work very well, because I see no water when I open the filter drain.

110V Aux Air Compressor Install
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Question on air system - filling the air tanks with my shop compressor

Reply #15 –
Without some objective measurements the temperature of the air air coming out of the small compressor or after 10 ft if air line is likely to be not much different.  I used an over pressure relief valve, a 10 micron water separator/filter that automatically purges water when the compressor stops, a chack valve, a  refillable descant air drier, a five micron filter and then the pressure switch all mounter on the end wall of the bay for access and ease of service.  There is about five feet of 3/8" nylon air line between the compressor and these components.  This setup is not as it was from the factory but more like it is on a 2002 and later but located in a more basement friendly place.It is set up to (but not connected) add air to the wet tank.  Wiring is different as well so that there is a driver's side switch to turn the pump on and off and if it is on another switch to open the solenoid valve to feed air to the wet tank.

The compressor is the one used on the 2002 and later coaches, 1/3 HP and move volume. It is mounted on a shelf on the back side of the truss under the slide opening where the OEM compressor was.  This too is set up to be much more serviceable.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Question on air system - filling the air tanks with my shop compressor

Reply #16 –

Thanks for all of the good comments. I am currently testing the following modification.  I added pressure gauges to lines 75, 76 and the output from the 12 volt compressor.  I made up a desiccant dryer and filter like the units in the coach, but with quick connectors so I can add it at the end of the air hose from my shop compressor.  Notice that the air goes thru the desiccant dryer first, then thru the 5 micron filter.  My shop compressor has a large tank and I check the drain on the bottom frequently.  In the winter there is no condensate - the dew point is usually down to 0 degrees in the winter, today it is up to 30 degrees, still no condensate.  I also have a coalescing filter regulator with a drain on the output from the air tank for the compressor.  I think adding the desiccant dryer is a good idea when the air is humid in the spring, summer and fall. 

Desiccant dryer -
Amazon.com: Dryer, Desiccant: Home Improvement
Filter -
Parker 14F11BB Compressed Air Filter, Removes Particulate, Polycarbonate...

I also added a pipe tee with a shut off valve and male M-style connector just after the solenoid valve in line 76 which goes to the wet tank.  This connection pressurizes all four air tanks.  This allows for searching for air leaks and releasing the parking brake (use wheel chocks) so the U-joint can be greased.  I also wanted to air up the tanks before starting the engine so I can drive out of the garage without waiting for pressure to build so as to minimize the diesel exhaust in the garage.

The reason I added the air connection near the 12 volt compressor is that I felt it was a more convenient location and the equipment bay stays clean.

P.S.
Sorry about the upside down pictures, I tried rotating them and reposting, but they still appeared upside down.

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Ron Brestel
2004 U295 38' PBDS