80gal 5hp Amp Air moving Products Compressor Setup Help

[xJAMx]

Hello Everyone!

I'm new to the forum and would like everyone's opinion on a used compressor I just purchased. I picked up an 80gal 5hp(Baldor 230v Single Phase) Amp Air Moving Products compressor for $500. Its in pretty good condition although I don't know how it runs. I'm trying to get it setup and have a couple questions. I'm not going to run a magnetic starter do to the fact I was told by my uncle who owns a couple body shops that I would not need it. I'm debating if I should purchase a standard Condor MDR11 pressure switch or the Condor MDR3 pressure switch w/ overload protection?(I'm trying to save money)

The Condor MDR3 pressure switch is basically a pressure switch and mini-magnetic starter in one. It has an adjustable overload protection of 2.5a up to 30A. The cost of the MDR3 is $153 compared to the MDR11 at $36.

If I do go with the MDR3, how much overload protection do I need?

Also, will I need a switch with a compression unloader? The guy who I bought it from was running his paint shop with it and the pressure switch he was using doesn't have an unloader.

Let me know what you guys think. THANKS!

 

[md21722]

You cannot run the MDR11 with a 5HP motor. It is only rated for 3HP. I wouldn't even bother with the MDR3 for $153. The magnetic starter is the best way to go, and is roughly the same cost. This is what I would do, and have done:

1. Buy a Square D magnetic starter for $130. http://www.ebay.com/itm/272131202090?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

2. Buy a Square D pressure switch for $30-37. http://www.ebay.com/itm/281910242142?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT If you can get a Zoro coupon, they will be closer to $30.

If you think about it, the only 5HP compressors that don't have magnetic starters are the value priced ones from your big box stores.

Remember that proper wiring for a 5HP compressor calls for #8 NM-b (Romex) or #10 THHN (in conduit). You can generally use a 30A breaker but up to 70A is allowed to prevent nuisance tripping if you have the correct thermal protection (motor has it, or magnetic starter sized correctly) and are using the correct wire/wire size. A disconnect is required if the compressor if the panel is more than 50 feet away or out of line of sight. These are cheap, less than $10 at Home Depot or Lowe's.

 

[xJAMx]

Ok, great! I was going to purchase from eBay so should I order the items from the links you posted?

Also, how do I know if this compressor needs compression unloading?

Thank you for helping me set this up. I've never had a compressor this size before other than the shops I work at.

 

[md21722]

I need to read up on your specific compressor for unloading but I do recommend the exact eBay links above. I am running the magnetic starter & pressure switch linked above, purchased from those suppliers (eBay tells me I bought this item before).

 

[md21722]

As far as I know your compressor has a centrifugal unloader built into the pump so you don't need a pressure switch with one. There is no harm in buying a pressure switch with one and not using it.

 

[xJAMx]

Ok, I will order these now. Once they come in I will definitely need help wiring it up. Will a 30A two pole breaker and 10ga copper wire be sufficient enough to run from main box?

 

[md21722]

Re-read my post. Wire size depends on wire type. 30A should be fine either way. No plugs allowed. Post up in Lighting & Electrical if you have more questions about wire size... The key with the Square D mag starter is that it runs a 230V coil. One leg is already run for the heater/thermal element. You need to complete the second half of the coil circuit with the pressure switch. So you need one wire from the line in going to your pressure switch and the return from the pressure switch going to the coil. If you mirror the maroon wires already there, it will work. Post up pictures with any questions.

 

[xJAMx]

I just ordered the magnetic starter and pressure switch from the links you posted. As soon as I receive them I will post pics and start wiring it up.

 

[xJAMx]

Question: My tank says 200Psi MAX. The pressure switch you post is rated for 135/175. Is this the one I need?

If you look at the pictures of the pump, there are two release valves connected to the left and right of the cylinder head. They are looking a bit worn out and would like to replace them but I'm not sure what PSI rating I need?

 

[md21722]

Yes, you want the 135/175 pressure switch. The pump is probably not rated for 200 PSI and there is a buffer between operating and maximum tank pressure anyway. Your tank safety should be 200. If the safety pop off valves work, I would leave them. You can download a manual for this pump from Eaton Compressor website. On my Champion the interstage safety (left) is set around 75 PSI. The high side is probably 200 PSI. I'm not seeing the right side safety valve.