# Vacuum pump?



## dthornton (May 10, 2017)

Okay, I  need some help here.  I purchased a mini split unit; long story short, I'm going to have to install it myself. I am not searching for top grade professional equipment; I only have this one unit to install and possibly a second one later for another room. So, I'm looking for a vacuum pump and gauges. Online, I found many - ranging from about $89 up to well over $600 for a vacuum pump and gauge set. Some mentioned R-134a (I know that is for auto A/C units) and others mentioned different refrigerants or didn't mention any at all. Questions: 1) Would a pump/gauges on the low price end work satisfactorily for installing just one or two units?  2) Is there a difference between pumps for automotive A/Cs and for household units, or will "any" pump work for "anything"? 

My mini split came with great instructions, and is pre-charged. After pumping a vacuum and waiting a couple of hours to ensure no leaks, I just open a valve and the system is charged. It also came with the copper tubes with fittings, but they're several feet too long, so I must shorten them. I also need a tubing flare tool and a flare nut torque wrench. (I want to D-I-Y, but also want to do it correctly). I would like to get by with an investment of a couple hundred dollars for everything. Can y'all please give me recommendations for tools that will do the job but not break the bank? Thank you for any and all help you can offer. :help:


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## nealtw (May 10, 2017)

With a couple extra feet of tubing you can try a few until you learn how. Don't forget the nut.
[ame]https://www.youtube.com/watch?v=TcpsSu4deuQ[/ame]


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## dthornton (May 11, 2017)

nealtw said:


> With a couple extra feet of tubing you can try a few until you learn how. Don't forget the nut.
> https://www.youtube.com/watch?v=TcpsSu4deuQ




Neal, thank you for the video. I've done brake lines before (long ago), so it shouldn't be too bad. What about a low cost vacuum pump and gauges, though?


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## nealtw (May 11, 2017)

dthornton said:


> Neal, thank you for the video. I've done brake lines before (long ago), so it shouldn't be too bad. What about a low cost vacuum pump and gauges, though?



I have used a flare tool once in my life and less experience with with vacuum pumps, sorry.


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## dthornton (May 12, 2017)

nealtw said:


> I have used a flare tool once in my life and less experience with with vacuum pumps, sorry.



Hey, Neal, I appreciate the advice and your willingness to help.  

I'm in the proverbial "rock and hard place" .... one HVAC pro wants nothing to do with the installation - only to vacuum it down and then open the valve to release the refrigerant into the system. Which he'll gladly do for a couple hundred dollars!  The pro who is willing to do the install wants way more than the unit itself cost.  I already have the 120 line on its own breaker run to a box in the area where the outside unit will go. I guess it will take me the better part of a weekend since I've never worked on refrigeration (other than to recharge a car A/C), but I'd bet a "pro" could do it all in a couple of hours. Even though I've never done it, I feel confident I can handle it if I have the right tools. The instructions are good, and in the past I have worked in machine shops and worked on big aircraft (727, etc.) .... in other words, I can handle mechanical stuff. 

Don't we have a couple of HVAC pros on this site who can tell me about the pumps and gauges? I don't want to spend the money on the internet to purchase a pump and gauges that will be absolutely no use to me. :help:


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## nealtw (May 12, 2017)

dthornton said:


> Hey, Neal, I appreciate the advice and your willingness to help.
> 
> I'm in the proverbial "rock and hard place" .... one HVAC pro wants nothing to do with the installation - only to vacuum it down and then open the valve to release the refrigerant into the system. Which he'll gladly do for a couple hundred dollars!  The pro who is willing to do the install wants way more than the unit itself cost.  I already have the 120 line on its own breaker run to a box in the area where the outside unit will go. I guess it will take me the better part of a weekend since I've never worked on refrigeration (other than to recharge a car A/C), but I'd bet a "pro" could do it all in a couple of hours. Even though I've never done it, I feel confident I can handle it if I have the right tools. The instructions are good, and in the past I have worked in machine shops and worked on big aircraft (727, etc.) .... in other words, I can handle mechanical stuff.
> 
> Don't we have a couple of HVAC pros on this site who can tell me about the pumps and gauges? I don't want to spend the money on the internet to purchase a pump and gauges that will be absolutely no use to me. :help:



Yeah I am surprised no one has chimed in.

I will have a look and see if I can find someone.


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## nealtw (May 12, 2017)

http://hvac-talk.com/vbb/showthread.php?432822-Looking-for-best-residential-vacuum-pump

You may have to join to read this stuff.


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## Chris (May 12, 2017)

Harbor Freight has one and with there 20% off coupon should be under a hundred bucks. Should work fine. On the gauges check there as well, the R-134 gauges cover a few different fluids, which coolant does your mini split take? I can look at my gauges and see which one you will need at least. One good thing about getting the pump and gauges is that if you ever need to do a car you have the set up and R-134 is cheap in the 30 pound can.


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## havasu (May 12, 2017)

Is this the new fluid with the extreme high pressure gauges? My bro in law quit working on the a/c systems on the new units because the gauges were ~$600+.


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## dthornton (May 12, 2017)

The mini split uses R410a, I believe. It is a Senville unit.


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## Chris (May 12, 2017)

https://www.amazon.com/dp/B01IPACSUQ/?tag=skimlinks_replacement-20

https://www.amazon.com/dp/B00E8SLTXW/?tag=skimlinks_replacement-20

For less than 150 bucks you can do yours and any car with 134.

I don't use either of these, I have some pricier ones but I don't see why you would have an issue for occasional use.


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## dthornton (May 13, 2017)

Chris said:


> Harbor Freight has one and with there 20% off coupon should be under a hundred bucks. Should work fine. On the gauges check there as well, the R-134 gauges cover a few different fluids, which coolant does your mini split take? I can look at my gauges and see which one you will need at least. One good thing about getting the pump and gauges is that if you ever need to do a car you have the set up and R-134 is cheap in the 30 pound can.



The mini split uses R-410a refrigerant. I looked at Harbor Freight and was considering their pump. I need to pull -76cm Hg of vacuum. Will this pump do that? I have multiple HF tools, most of which are great (for what they are - cheap). My one concern in this instance is that HF tools only have a 30 day warranty.  If I need to do additional work and the pump craps out, I would have to buy a new one. However, if you think it will work, and it will pull the vcuum I need, I may give it a try. Thanks for the help!


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## Chris (May 13, 2017)

I don't have any personal experience with the HF pump. Mine is a different brand. I would assume it does but I would look into it more first or check out those Amazon ones and see what they can do


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## slownsteady (May 13, 2017)

Not knowing anything about vacuum pumps or AC setup. let me ask a dumb question: What difference does the refrigerant make? PSI is PSI, right?


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## oldognewtrick (May 13, 2017)

slownsteady said:


> Not knowing anything about vacuum pumps or AC setup. let me ask a dumb question: What difference does the refrigerant make? PSI is PSI, right?



http://www.ehow.com/facts_7729125_r134a-vs-r410a.html


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## slownsteady (May 14, 2017)

Okay, thanks. So the question is whether your vacuum pump can reach 200 psi, if needed? I am also just assuming that a decent pump can be dialed down to 70 psi if that is needed. I'm just trying to grasp the problem here.


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## kok328 (May 14, 2017)

I'm more worried about the shortening of the lineset. I would either leave it long or braze the connection. Again 410A is higher pressure than R22.


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## dthornton (May 16, 2017)

kok328 said:


> I'm more worried about the shortening of the lineset. I would either leave it long or braze the connection. Again 410A is higher pressure than R22.


I sent you a private message - need more info than what is posted here. Thank you for the help! 
:help::thbup:


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## dthornton (May 29, 2017)

To all: Thank you for the help and advice. I decided to not invest in equipment; I would need: tubing flare tool (a good quality one), tubing bender, torque wrench and flare nut (crow feet) wrenches, vacuum pump, nitrogen tank and gas, and a way to remove excess R410a (the line set will be shorter than "standard" when installed). 

Research revealed that R410a operates under very high pressure; therefore the tubing flares must be "perfect" and properly torqued in order to hold a seal. The lines must be pressure tested with he nitrogen prior to evacuation and releasing the charge into the lines. One mistake, and there goes many $$$ worth of R410a. I would really love to learn how to properly do the job, and do it myself. However, that's way too much investment in time and money for just one unit that (or even two).


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## slownsteady (May 30, 2017)

sounds like you made a sound decision in this case.


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## dthornton (May 30, 2017)

slownsteady said:


> sounds like you made a sound decision in this case.



Yessir, I'll leave this one to the pros. :thbup:

Mind you, I did not give up. It's just the realization that cheap tools would not (probably) work for a project like this, and the investment for the proper tools + the education to do it properly are way too much to just perform one job.


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