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Author Topic: Uniweld 5.5 cfm vacuum pump  (Read 710 times)

Offline afterblast

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Uniweld 5.5 cfm vacuum pump
« on: March 07, 2018, 09:33:17 PM »

 Iíve been working on replacing some of my older tools with newer neater ones.   For the last five years Iíve had the harbor freight single stage vacuum pump and while itís worked pretty well, itís been past due for an upgrade.   As a mini review Iím not knocking the harbor freight model, and if youíre just starting out or donít plan on doing a lot of sealed system work for the price you canít really beat it...  However Iíve been doing a lot more sealed system work and waiting around for that harbor freight unit to pump a system down to 500 microns was getting old.    I found this Uniweld  unit on Amazon for just about 250,  itís got a 1/2 hp motor, and is factory rated to 15 microns.  For curiosity sake I tested it out of the box after putting oil in it with my fieldpiece micron gauge screwed directly to the port on it, after about four minutes of operation it got down to 35 microns and then stabilized and couldnít pull it any lower... Not quite the 15 its rated for but the micron gauge is a little old so I donít think I can blame the pump and Iím not gonna complain about 20 microns especially because I didnít let it run all that long...   Got to use it today replacing the evaporator in of all things a haier top mount freezer  that was under extended warranty.   Flushed the system with nitrogen before  I started to vacuum it out, and this pulled it down below 500 microns in about 10 minutes.  Itís about the same noise level as the harbor freight pump although I will say it sounds faster probably due to the bigger motor.   For the price Iím pretty impressed and would recommend it.

http://amzn.to/2DdUtNR

Offline AJ

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Re: Uniweld 5.5 cfm vacuum pump
« Reply #1 on: March 09, 2018, 09:11:27 AM »
Good to know, thanks for the review!

Offline Larry the applia

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Re: Uniweld 5.5 cfm vacuum pump
« Reply #2 on: March 09, 2018, 05:57:36 PM »
 I would like to see your set up when you are doing a vacuum if you could take a picture and maybe a short video. I have a robinair vacuum pump dual stage and it takes me forever to get down to 700 microns. What manifold and hoses you using?also I use a supco vacuum gauge.
Larry Johnson
Shannons Appliance repair
Clarksburg, WV

Offline afterblast

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Re: Uniweld 5.5 cfm vacuum pump
« Reply #3 on: March 09, 2018, 07:04:26 PM »
Iíll try and grab some pictures on the next system I do customer depending..   but I use a yellow jacket 2 valve manifold with the vacuum pump and a fieldpiece svg3 micron gauge connected to a t fitting on the low side.  I think the biggest thing is before I start pumping down I flush the system with dry nitrogen and run it up to around 200 psi...  mostly because I then hit my joints with gas leak bubble spray, but also because it helps flush condensibles from the system...  I flush nitrogen from high side to low side and look for pressure rise on my low side gauge before opening it up to get up to pressure faster..  it might just be my own bias but I feel like this helps shove any moisture through the cap tube and into the low side... also if the nitrogen moves through then you know you donít have any restrictions since it wonít go backwards from high to low across the compressor (if it does you have bigger issues)..   after I pressure test it I vent the nitrogen out till I get the system down to 10-20 psi so I donít blow the oil out of my pump, then I start vacuuming down from the LOW side first until my high side gauge is in the negative... then I open both sides and let it rip...   also when you vent nitrogen from the low side you canít let it go too fast or youíll blow the oil out with it....   and since Iím back there I tend to try to use the venting nitrogen to blow the dust off the inside of the condenser coil...    Iím pretty excited actually though my new 4 valve gauge set came in and itís got the larger size vacuum hose so it should speed things along...   only other thing I wanna try to speed it up even more is to get a set of apion core removers so Iím able to vacuum it down without the valve cores in the way.. the more open of a path you have the faster it will go....   also I tend to change my pump oil out every 5-7 sealed system jobs or if itís been over a month since it was last changed..  the oil will absorb water from the air and lose some sealing ability over time...      I think Iíve got a lot of sealed system paranoia but to be fair I also have very few sealed system callbacks and we warranty our cash calls for a year so I doubt theyíd call anyone else.

Offline afterblast

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Re: Uniweld 5.5 cfm vacuum pump
« Reply #4 on: March 23, 2018, 09:59:33 PM »
Test posting some pics from a compressor replacement on a built in Thermador freezer
« Last Edit: March 23, 2018, 10:02:26 PM by afterblast »

Offline afterblast

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Re: Uniweld 5.5 cfm vacuum pump
« Reply #5 on: March 23, 2018, 10:07:28 PM »
Tight spot for a compressor,  vacuumed it down to just under 500, shut off the gauges and it stabilized at 791..    swept it twice with refrigerant while vacuuming down and it took about 30 minutes total.   Pressure tested it with nitrogen before I started pumping down.

Offline cmcrepair

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Re: Uniweld 5.5 cfm vacuum pump
« Reply #6 on: May 18, 2018, 11:26:24 AM »
I don't have any experience with the Uniweld one, but can vouch for this one at a similar price.  Been on mine for 2 years & going strong.

https://amzn.to/2J5HEZY