DYI Mini-split A/C vacuuming

[Phillthy]

just thought I would make a quick post to help those that want to purchase a mini-split ac unit but fear the vacuuming stage or do not want to call someone out to perform this duty for you.

you need to order 2 parts to allow you to complete this step of the mini-split install. one is a vacuum pump and the other is a manifold (gauges) with hoses. both of these parts can be had for a total of less than $300. Some manifolds are sold separately from hoses so you can buy them individually if you can not find them sold together. i am including part numbers for the parts i have actually used with great success. this process is easy and will only take a half of an hour to complete.

pump - Robinair 5CFM Vacumaster Vacuum Pump 15500

manifold - Yellow Jacket 42004 Manifold with hoses

now the process will be outlined in your units instructions but to simplify...

hook up the entire unit as your directions state. before powering on the unit you want to take the hose that is under the left gauge of the manifold and connect it to the service port of the unit you are installing. the hose from the center of the manifold will connect to the vacuum pump.

illustration

now you want the valves on the unit to remain closed. they are hidden under brass caps where you connected the line set to the outdoor part of the unit. the service port is located there as well.

with the line set installed and torqued to specifications and manifold connected to service port and pump, you can now vacuum the line set. make sure the valve on the manifold that corresponds to the left gauge is all the way open. you will see the needle stay at "0". now switch on the pump and let it run for about 15 minutes. you will see the needle drop into the negative. you want the needle to move all the way down to "-30".

you can see "-30" at the bottom left side of the gauge.

after 15 minutes of vacuuming, close the valve on the manifold for the left gauge and switch off the pump. this is the "leak test" portion of the procedure. you want the needle to stay at "-30" or wherever it was close to that when you closed the valve. wait for 5-10 minutes and ensure the needle has not moved. this indicates there are no leaks in the line set (usually connections) between the indoor and outdoor portions of the unit. if the needle has not moved... you should be good to go. disconnect the manifold from the service port and open the valves on the outdoor unit as specified in the directions.

that's it! hope it helps a few of ya

 

[Guest 18340]

Right on Phillthy! 'Tis the EXACT way I installed mine. I used a different brand pump but the point is to get a good 2 stage pump.
The graphics you posted are very typical with mini splits, damn near every brand has those same graphics
Some folks are going to argue that you should run the vacuum pump longer, and theirs certainly no down side to vacuuming longer, but the fact is that it is exactly what the manufacturer calls for.
K++ bro

 

[RedRain]

Nicely done

Butthe needle moving also indicates moisture present in the system*

A good technician will do a triple nitrogen purge on an r410 system*

 

[Phillthy]

yes charging with nitrogen then testing with a bottle of water and a drop of dish detergent is actually better but for the DIY method i tried to keep it simple. a good vacuum pump will vacuum all air and moisture from the line set.

 

[louie]

Great post! With the help of evlme2 and you I should be able to install my new mr.slim in no time. Just got it the other day! I'll keep you guys posted

 

[gashouswidow]

Just received my Mr. Slim today will be installing Monday. Picked up a 2 stage vacuum pump at Habor Freight.

 

[DnKNg5]

Using gages is fine but if you really want to make sure you're removing all the moisture from the system, which is the most important aspect of the line set installation, get a vacuum gage. You can get an analogue one that measures in Inches of Water Column or a digital one that will measure Microns. Moisture in a system usually boils off at about 800-900 microns so if you see your gage fluctuating for a while at those numbers, that is why. It doesn't necessarily mean you have a leak. Proper leak testing should only be done with Nitrogen. I can't tell you how many times I have seen guys perform a leak test by pulling a vacuum, only have to return to the job a month later to refill the system because of a slow leak they didn't catch. You want to pull a vacuum down to 500 microns. As Phillithy was saying, let it hold steady for about 5-10 minutes to determine that your readings aren't going to start rising.

Just to clarify, you CAN use a vacuum pump to leak test and if you did everything correctly you most likely WON'T have leaks. But if you don't and you do have a leak, your DIY job just got a lot more complicated. Unless you have access to R410a refrigerant, you will have to call a company to recharge your unit, which shouldn't be a big deal except for the fact that if they are going to charge it PROPERLY they will have to have access to the area that the indoor unit is servicing.

Hope this was of some help! Great post Phillithy!

 

[RedRain]

yes charging with nitrogen then testing with a bottle of water and a drop of dish detergent is actually better but for the DIY method i tried to keep it simple. a good vacuum pump will vacuum all air and moisture from the line set.

no you obviously are an amateur and not a professional

re-read what i wrote

any good technician will triple purge with nitrogen when installing an r410a system. You fill the system to 200psi with nitrogen not only to test for leaks but to clean the lines. You release the charge of nitrogen and repeat this process 3 times. R410 is a very picky refrigerant, and proper precaution and steps should be taken to ensure a long system life.

R410a systems must be vacuumed down to at least 500 microns..you need a micron gauge when dealing with r410.

This is the difference between someone who does this for a living, and someone who watches you tube videos and who has no formal training or experience.

 

[Phillthy]

no you obviously are an amateur and not a professional

re-read what i wrote

any good technician will triple purge with nitrogen when installing an r410a system. You fill the system to 200psi with nitrogen not only to test for leaks but to clean the lines. You release the charge of nitrogen and repeat this process 3 times. R410 is a very picky refrigerant, and proper precaution and steps should be taken to ensure a long system life.

R410a systems must be vacuumed down to at least 500 microns..you need a micron gauge when dealing with r410.

This is the difference between someone who does this for a living, and someone who watches you tube videos and who has no formal training or experience.

actually a "professional" showed me how to do the first install. this is a DIY thread so yeah... im an amateur. however, when shown how to do it with nitrogen and how to do it with just a vacuum and gauges, i felt the DIYer would like the simplest, cheapest solution. i have installed both ways and all of the systems i have done have years of service without a glitch. i understand that HVAC guys want to get paid but so do drug dealers, yet we all grow our own herb.... so i will install my own stuff. the method i described works and works well. in fact it is how mitsubishi itself tells you how to do it. it is in their install guide.

amateur and proud of my accomplishments. i also wired up every room i have installed. sub panels, 240v, 120v, etc... all to code.

now i could have told everyone the cheapest method of charging the lineset with the 410 by opening the valves then leak testing with a spray bottle filled with soapy water but releasing refrigerant into the air wouldnt be responsible of us so i opted for second cheapest solution.

BTW gang there are tons of vacuum pumps and gauges to be had at your local pawn shops for a fraction of the price new.

 

[smoke1sun]

no you obviously are an amateur and not a professional

re-read what i wrote

any good technician will triple purge with nitrogen when installing an r410a system. You fill the system to 200psi with nitrogen not only to test for leaks but to clean the lines. You release the charge of nitrogen and repeat this process 3 times. R410 is a very picky refrigerant, and proper precaution and steps should be taken to ensure a long system life.

R410a systems must be vacuumed down to at least 500 microns..you need a micron gauge when dealing with r410.

This is the difference between someone who does this for a living, and someone who watches you tube videos and who has no formal training or experience.

Yeah the difference is the pro wants to take our money, and the amateur is trying to help us save a lil cash and not compromise security.

Show us how a pro would do it.

This is a good DIY, gives folks who's considering a mini some some obstacles to consider. THANKS PHIL

 

[Iron_Lion]

Great tutorial, I don't need a a mini split YET but if and when I will be doing it myself

 

[RedRain]

Lol. Refrigerant doesn't make soapy water bubble only nitrogen does you are obviously an amateur.*

I am telling u the proper way to do it.

Ya not doing oil changes regularly on your car *is cheap aswell but not safe. *Your reason is fucked cause you are a hack job or were taught by a monkey*

You can't just not do something that is critical especially with r410 you obviously have minimal knowledge about AC
Its not a choice to follow my directions it's the way it's supPosed to be done

 

[DnKNg5]

Lol. Refrigerant doesn't make soapy water bubble only nitrogen does you are obviously an amateur.*

I'm sorry RedRain but Phillithy is right about the soap bubbles test. Any hole that has positive pressure over the atmosphere will cause bubbles to form. This test is used on natural gas when running gas lines as well. It is the cheapest and most reliable way for checking for vapor leaks in suspect areas.

 

[Phillthy]

Lol. Refrigerant doesn't make soapy water bubble only nitrogen does you are obviously an amateur.*

I am telling u the proper way to do it.

Ya not doing oil changes regularly on your car *is cheap aswell but not safe. *Your reason is fucked cause you are a hack job or were taught by a monkey*

You can't just not do something that is critical especially with r410 you obviously have minimal knowledge about AC
Its not a choice to follow my directions it's the way it's supPosed to be done

listen chief, i have done it and it works. this thread is for DIYers and you obviously are much more advanced than us mere mortals so why don't you start a thread on how to call an HVAC guy and drop mad money to do the same things i outlined above instead of trolling this thread?

i have changed my own oil for 25 years and never had an oil related mishap.. not once. i also install all my own electrical circuits, build my own decks, rebuild my own engines, build computers, and troubleshoot the worlds fiber optic problems. i think i am capable of installing a minisplit. hell my 16 year old is too. its not rocket science. its following directions.

yes 410 will make soapy water bubble. any thing blowing out a small hole will. its a gas in the line and when the gas escapes from a leak the soapy water bubbles. i have done it with nitrogen and with 410. i have also done it on automotive ac systems and my tires to find a puncture. works all the way around.

here is a link to the mitsubishi install guide.
http://www.acwholesalers.com/v/vspf...i_mr_slim_msa_msy_msz_09_12_15_17_install.pdf

no mention of nitrogen, no mention of triple pressure testing, no mention of micron gauges... just a vacuum of the lineset and a 2 minute wait to see if the needle on regular a analog gauge moves. since they provide the warranty for my unit, i feel it prudent to follow their directions.

yes your method works. yes mine works. the proof is in the units installed and their error free run time. the difference is i dont have to pay a few hundred dollars to some guy that went to school for a month and took a test. im fully capable of doing it myself... hence the DIY thread. it is a DIY method that works. i can also buy 30lb tanks of 410a without a license. you gonna call the HVAC police on me?

you wouldn't happen to be out of work would you? whats got ya so swole?

 

[DnKNg5]

you wouldn't happen to be out of work would you? whats got ya so swole?

Mr. Hammer, meet Mr. Nail.

 

[RedRain]

ya do u think a little manual will explain a whole trade?

you have no respect or knowledge

ya i am too busy setting up 100+ lighters!!

you think because you can read an instruction manual that you have the proper knowledge to handle and install HVAC systems?

lets see some big systems that you have both installed, oh sorry you just install little mini splits...

you dont soap test a refrigerant , you use nitrogen, again your misinformation

wow it amazes me how people think they know everything! you have no training in the HVAC trade, yet you are both grand masters aparently cause you change your oil and can build a deck!! LOL

i bet you dont even purge your guages with nitro before hooking up...

 

[Guest 18340]

Hey RedRain, why don't you chill out man. You came to this thread throwing boogers and say others have no respect?
The fact is that what Phillthy posted is EXACTLY what Mistsubishi calls for when installing their system. No Nitrogen, no micron gauges.
It is the way I've installed plenty of mini's and all are humming away.
Nobody is implying they know everything, just that we know how to install a mini split according to the manufacturer.
You're taking things way too personal.
K+ Phillthy for taking the time to help us common folk

 

[Buzzsmirk!]

if you are only needin the stuff once!!

if you are only needin the stuff once!!

by the way peeps..... harbor freight tools has a vacuum pump on sale somtimes for 60 bux and a line
/manifold gauge set for 40 bux when on sale.

worked just fine on y mini-split install(s)

peace!!

 

[One Love 731]

Thanks Phillthy. I'll be DIY'n a few mini splits soon, cant wait to get dialed. This should make things easy1

 

[Andyo]

thanks

thanks

Nice one mate.
Is how i did mine after reading translated malaysian instructions.
been running fine a year now.A