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Topic: HWH Compressor (Read 496 times) previous topic - next topic

HWH Compressor

I finally getting ready to add a filter, dryer, water separator for my HWH Compressor as I have seen others do.  My question is, Can the square box pressure switch be replaced with one similar to this one ?

Air Pressure Switch 90-120 PSI Pressure Switch 1/8"-27 NPT Air Compressor...

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Mark & Bev
2001 U295 36' Slide
Cummins ISC 8.3 350HP
Build #5802
Jeep Wrangler Toad

Re: HWH Compressor

Reply #1 –
Mark, I'm in the middle of completely replacing the Thomas pump, solenoids/wiring, pressure sensors, etc in my coach right now.  It's basic electrical and yes, you could use that pressure switch to run your compressor.  The stock pressure switch in my rig comes on at ~65psi and goes off ~85psi.  The specs for the Thomas 4101 pump show it only makes about 0.95CFM at 100psi though, so this is why it takes a while to build pressure above that point.  It is also rated for a max of 100psi.

I'm going to be adding a few extras myself.  I've purchased a digital pressure switch so can set the on and off pressure digitally, and for a wider differential.  I plan to have it turn on at 65psi, like now, but off at 120psi, so there should be a much longer window of time between runs.  I'm adding a switch that will override the pump completely.  ON-OFF-AUTO, so I can shut it off completely, auto so it runs off the digital pressure switch and ON to run manually.  I'm putting a 140psi pressure switch in the system so it will never get over this, even when in the ON position.

I'm also adding a start-delay relay on the HWH signal wire...the one that tells the pump to run when the leveling system is trying to raise the coach.  Since it's possible I will have enough air to lift the coach without having to turn on the pump, this relay will add an adjustable delay.  I plan to set it at 20-30 seconds to start.  If the HWH can't level the coach within that amount of time, then it will run the compressor.

The compressor I picked is an Air-Zenith OB2.  At 100psi, it is rated for 2.47CFM, so 2.5x the Thomas pump.  From my measurements, it's a few db noisier than the Thomas and pulls about 7 more amps (35max vs 28), but I don't think that will require changing the wiring, since it will likely run for less time than the Thomas, when it runs.  Plus it was $360 out the door with a 2 year warranty, here in Vegas.

This is a project I will be starting this weekend.  I'll post a thread with all the specifics once I get started.
Keith
2003 U320 38' #6197

Re: HWH Compressor

Reply #2 –
Gentlemen
Any chance of photo documenting your install?  I am interested in at least doing some maintenance on my "smaller" model Thomas compressor and am a bit challenged in the understanding of the process etc
Peter
Peter    Alberta Canada
'98 U320 40'  Build 5359 M11 450 HP, Aqua hot, Blu Ox
 

Re: HWH Compressor

Reply #3 –
Yes, I'll be documenting the swap out including noise measurements at the pump, outside the coach, inside the coach, time to pressure, etc.

I already started a thread as I was trying to pick a pump here:  Replacing the aux compressor and HWH pressure requirements
Keith
2003 U320 38' #6197