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Topic: Minimum Air Pressure When Parked (Read 687 times) previous topic - next topic

Minimum Air Pressure When Parked

As we park for longer periods at campgrounds I'd like to know if it's important to periodically start the engine to rebuild air pressure?  After 5 days both tanks are currently showing 50 psi.  If left would these tanks go to zero?  Any harm?
Randy (N4TDT) and Karen Crete
Sarasota, Florida
SOLD:  2000 U270 34' WTFE Build 5756 "Ole Red"

Re: Minimum Air Pressure When Parked

Reply #1 –
IMO, no harm if the air tanks go to zero.  Some coaches take longer than others to get to that point, which is good, cuz it indicates a "tight" air system.  Even with zero pressure in the tanks, the air bags will hold pressure for a long time.  When they do finally sag, the HWH aux air pump will add air to them, but only if it is required to maintain the auto-level.

Some members worry about having to drive off in a emergency situation when the air tanks are empty.  Our old coach only has to idle for about 10 minutes to bring the air from zero to 100psi, at which time the air bags are fully inflated.  I think that is quick enough to get the coach moved under almost any imaginable situation.

Starting and idling the engine just to maintain air pressure is not recommended.  Some of us have permanently installed 120V air compressors in our coach, complete with filters and water separators, so we can "air up" to operating pressure without running the engine.  Here are a couple threads - there are others:

Pancake compressor (split from How long to build air pressure?)

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: Minimum Air Pressure When Parked

Reply #2 –
No need to keep the pressure up.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Minimum Air Pressure When Parked

Reply #3 –
Just curious, since I don't have an on board compressor, will the air dryer function while filling from my shop air with engine off, and a valved tee upstream of the dryer. Or is there a heater element in the dryer that always on?
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Minimum Air Pressure When Parked

Reply #4 –
Quote from: Old phart phred –
Just curious, since I don't have an on board compressor, will the air dryer function while filling from my shop air with engine off, and a valved tee upstream of the dryer. Or is there a heater element in the dryer that always on?
Heater is on with ignition, but you are going through the filter
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Minimum Air Pressure When Parked

Reply #5 –
The electric heater is just there to keep the purge valve from freezing in sub-zero conditions.  Heater has nothing to do with the air drying function.
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: Minimum Air Pressure When Parked

Reply #6 –
My air tanks go to zero within 24 hours or so.  My airbags hold steady pressure for more than 3 months.

I do need to replace some  air system components someday.
1998 U320 40'
2005 GMC Yukon
MC# 17609

Re: Minimum Air Pressure When Parked

Reply #7 –
Looks like I am in luck, fitting going into air dryer is pipe thread, and there's room for a tee and a nipple. I started my coach last week sometime to get it raised up a bit to work on it, it's now down to 35 psi rear and 95 in the front, I can fit under it with the bags completely deflated with about 2" clear. But it's not easy. Adjustable 27" tall jackstands would be safer if a tire blew.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Minimum Air Pressure When Parked

Reply #8 –
Quote from: Old phart phred –
Looks like I am in luck, fitting going into air dryer is pipe thread, and there's room for a tee and a nipple. I started my coach last week sometime to get it raised up a bit to work on it, it's now down to 35 psi rear and 95 in the front, I can fit under it with the bags completely deflated with about 2" clear. But it's not easy. Adjustable 27" tall jackstands would be safer if a tire blew.
I would suggest having a air drier on the air compressor line, when using a outside compressor.
Chris and Tammy White  CDA Idaho
Previous owners 1997 U295 36' 3126 Cat 300 HP Build # 4998
Former Foretravel tech & RVIA certified tech
Former owner Custom Satellite home/RV satellites 
Former owner Vans LTD  van conversions
Unemployed, panhandler, drag racer NHRA #6348

Re: Minimum Air Pressure When Parked

Reply #9 –
I don't get how that would be different, upstreame of the coach air dryer?
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake