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120v air compressor replacement
#41

Quote:when i was down to 20 degrees this past spring in utah, one night my compressor froze up. it struggled but i am sure there was moisture in it that had frozen. i bet if you put simple heater in there it would keep it from freezing. i bet there is nothing wrong with the compressors....

(Hey Tom!) Yeah, my second one definitely just froze up. The first one, unfortunately, just gave up the ghost. I'm currently running a heater in that bay, indeed. I'll probably wire something with a thermostat into the existing 120V circuit down there, eventually.

Quote:I got water in the little solenoid that relieves the head pressure and it froze. Caused all sorts of problems. It finally cracked and when I removed it, all was well again. After two years, I finally replaced it.

Thanks Bill. My solenoid seems to be working okay. It's interesting that you ran for two years without one. Are you running the Thomas compressor? I feel like I can't get more than two years out of mine anyway, and I hate listening to that blowoff squeal. Maybe I should take mine out! Smile

Quote:Is there a reason you have them set for 120 psi?

Hey Richard, yeah... I think that is just something that's required for this coach. If I could get away with 90psi, that would open up a whole lot of other alternatives for the compressor, though.

Quote:The second issue is that the push to connect fittings in the air system leak profusely at colder temps.

Slowly, but surely, I have replaced almost all of the speedfit connectors in the system. There are probably some buried behind cabinetry that I haven't gotten to, but under the coach I think is all compression at this point, thank goodness.

That said, in this freeze, we have had fail:

1) fuel filter housing on genset (so diesel went everywhere, instead of air)
2) slide seal
3) air separator at 120V air compressors
4) pressure regulator for genset airbags
5) one Thomas compressor

All in about three days!

Quote:Cold and humidity is your enemy. I too have had this problem. I placed a small heater on an extension cord in my air compressor compartment when we were in the single digits. I had the sensor freeze up and break due to Ice expansion. $110 lesson to replace the sensor.

Yeah... I've given in as well.

Quote:As far as adjusting the pressure, for me its a Siemens controller, I tried to go into my program and lower the Preset pressures, because I think I'm smart enough. I'm not. Clint Eastwood says " a man needs to know his limitations". sometimes I need to be reminded. New lesson, I SCREWED IT UP. I had to send it back to Valid in BC for them to reprogram back to factory specs. No Charge by Valid, but is was 2 weeks of controlling the pressures by hand. Valid Told me that I need the designed pressures for the leveling system. If it wasn't for the leveling system, I could stay at 60 to 70 psi. for the slide seals, toilets and door.

And what pressure did you start at? The 125, like mine?

It's interesting that you went in there and tried hacking that thing up. Mine has a black, plastic box with a Valid sticker on it below a grey box that has two digital hour meters and a bunch of 120V wiring inside. The grey box was functional when we started out, but gradually the displays have stopped working/reporting any hours at all. However, whatever logic does the switching on and off, and the toggle that lets me cut over to the alternate compressor, does still work. So I haven't touched it.

One thing I did have to do early on is replace the plastic (ABS?) hoses that Newell installs between the compressors and the manifold. Those were blowing out under heat/pressure, as mentioned earlier in this thread. That plastic tubing is only rated to 120psi or something, to begin with. I didn't know about braided hose, but I just got a 2-foot airline whip on Amazon, and it seems sturdy and has been working fine for a couple years.

2008 Newell #1234
Boulder, CO

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#42

And what pressure did you start at? The 125, like mine?

Answer; Coach 784 starts the Air comp at like 90 ish and turns off at 105 ish as i remember

One thing I did have to do early on is replace the plastic (ABS?) hoses that Newell installs between the compressors and the manifold. Those were blowing out under heat/pressure, as mentioned earlier in this thread. That plastic tubing is only rated to 120psi or something, to begin with. I didn't know about braided hose, but I just got a 2-foot airline whip on Amazon, and it seems sturdy and has been working fine for a couple years.

Answer; Again on my coach (which may not be original) I have a coil of copper line between the compressor and the water separator, I believe in an effort to help cool down the hot compressed air so the separator can do its job better. I don't have any light weight tubing other than D.O.T. approved air line tubing in my system.

Dave, Karen, w/Buddy and Moose. 
06' Newell #784
towing a 05' Featherlight enclosed trailer for toys and tools, 
or a 21' F350 Big Grin w KTM 300, and MTB in the back
35' Packard 4 dr convertible
59' Nash Metropolitan
+ 4 more cars and 8 motorcycles


Carpe Diem. Have Fun
Tomorrow is not guaranteed.
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#43

Okay, I am having even more problems late at night in the cold, even though I have the bay heated to 50F now. I am not sure if previous cold nights have worn out some part, or what.

But: I have discovered quite a few more of these dual-piston compressors. Most are only rated to 125 or 135psi, but for the price I am going to try them anyway. I can go through a lot of these $100 units before I buy another $500 Thomas one.

The first one is a Cal Air Tools SP-9413, a 1hp model. They make two even lower-powered versions of this pump, but they are the same size and were not as readily available to get shipped in this week. Amazon warehouse has some "good" ones for about $90.

The second one is a Metabo EC28M. This is a standalone compressor with a tank, regulator, etc. I'm probably going to use it via my shop air input for right now, because I think I need to disassemble the whole Valid-supplied compressor system and replace some parts that are questionable. But I might also just disassemble it and try to use the motor directly, later. I don't really have the space to carry around a whole separate compressor + tank long term. Right now this unit is on sale for about $120.

2008 Newell #1234
Boulder, CO

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#44

Here is a diagram of the Valid-supplied 120V compressor system that is on my coach, and I believe it is also on all newer Newells.

A few things to note, mostly for the next guy who comes along to this thread trying to figure stuff out:

1)  They are still using the same Thomas compressors.

2)  My coach had a plastic air separator, which promptly cracked and failed in our sub-zero temps here.  I replaced it with a metal one, and that is also the one they show in this diagram.  As of today, these are cheapest if ordered directly from SMC.

3)  The dump valve/solenoid is a custom SKU from Spartan Scientific.  I am concerned that mine is malfunctioning in the deep cold, leaving head pressure on the compressor and causing it to stall.  I have not yet called Spartan to figure out what is unique about our special model.

4)  The compressor hour meters inside that metal box are totally standalone from all the digital control logic.  They are just "dumb hour meters," per Valid.  Both of mine are dead, so I am going to try to find a replacement.  It would be nice to know the runtime on these motors.

5)  This diagram doesn't show any of the airlines, but you can see the tee in the front center that lets both pumps to go the cooling coil.  The short plastic lines between the compressors and that tee are the problematic issue in the systems installed in coaches of my era.  Valid says they are using braided lines on new installs of this system.

6)  I am also somewhat skeptical of my pressure transducer.  I think Valid has sourced different transducers over the years, and they have custom firmware in the I/O module that maps the response curve for each model.  This means if you want to replace the transducer, you probably also need Valid to update or swap your controller.

7)  The controller has a 12VDC enable line that, well, enables the system.  Mine has failed -- even if I switch off the "120V Compressor" button up in the galley, the computer still runs the compressors.  (Of course I can turn the whole thing off at the circuit breaker.)  I'm about to tear apart the whole connector and see if I need a new controller or what.  

I am having so many problems with this system right now, it is ludicrous.  I'm close to just ripping the entire thing out and building a whole new one that doesn't use any of the parts that Valid uses, just to see if I can get something that actually works.  Smile


[Image: qinM500.png]

2008 Newell #1234
Boulder, CO

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#45

I tried to find an alternative to the Spartan solenoid valve. Newell stocks them at close to $100. I did not get as far as reverse engineering the system...but what it needs to do is pretty simple. When the pressure drops and the system turns the pumps on, the solenoid needs to close. When the pump turns off, the solenoid needs to open thus relieving the pressure on the pump head.

Next time mine goes out, I will find a cheap replacement.

Bill

Bill Johnson
Birmingham, Alabama
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#46

FWIW,

There are some pretty universal and straightforward way to work around this issue. Air compressor relief valves are common, and used on about any small to mid size consumer compressor. This gives you and idea https://www.amazon.com/Secbolt-90-120PSI...WNrPXRydWU=

That takes care of relieving the head pressure on the compressor. You will need a check valve after the pressure relief device to keep the system pressure in the system.

Instead of the problematic auto dump water separator, install a 1 to 3 gallon ping tank in the bay with a manual drain. Loop ten feet on airline from the compressor into the tank to give at maximum effect at cooling the air and condensing the water vapor. Ok, so you have to drain the tank once a month. I have a quarter turn valve on mine with the exhaust piped to extend slightly below the frame.

I have a very similar setup which has been problem free for five years.

You will have to find a way to use the 12VDC signal to turn the system on from the Valid computer.

Richard and Rhonda Entrekin
99 Newell, 512
Maverick Hybrid Toad
Inverness, FL (when we're home Cool )
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#47

Good point, Richard. This is not rocket science, and I think the Valid system seems a bit overengineered. But, maybe there are good reasons why they did some of the things they did, the way they did them? I don't know.

I'm not sure I'd be willing to trade better water separation for one less compressor on board, given how unreliable these compressors have been for me. With the space I have available, I suppose that would be the trade for a ping tank.

2008 Newell #1234
Boulder, CO

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#48

Ping tank can be in the ceiling or in the wheel bay.

Richard and Rhonda Entrekin
99 Newell, 512
Maverick Hybrid Toad
Inverness, FL (when we're home Cool )
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