Buying mini-split - is my pump sufficient?

[TimeOrMoney]

I am going to install a small, single head Senville mini-split, and trying to collect the proper tools. My current HVAC pump is a 1.2 CFM pump, which should be sufficient for 22 feet hose evacuation, but I notice that a lot of professionals remove the valve core first, which reduces resistance.

The pump is plenty fine for a diesel truck A/C (R134a, not R410a). I can just let it run longer on the mini split than would be required with a 3.5 CFM pump, as long as it gets below 500 microns.

Opinions? The Senville instructions don’t call for using a micron vac gauge, which would be the best way to find out if it can pull enough, but I don’t want to buy one for just one job. I know all you professionals would do a better job, but this is at a remote cabin and many have been successful with DIY level tools.

Also, can anyone recommend a good eccentric flare tool?

 

[428PI]

I didn't remove no valve core or reflare any lines when I installed my Pioneer. I think sometimes the more one does the more one gets into trouble.

 

[brewchief]

The lower CFM pump will be fine provided in can pull below 500 micron. Realistically the only way to know is with a micron gauge. Fresh vacuum pump oil is always a good idea, I can tell when it starts taking longer to pull a good vacuum that its time to change oil, working on a dirty system with lots of moisture it might get changed several times before a good vacuum is pulled.

I have a Blackmax flare kit that will make a great flare 99% of the time, has a go no gauge that takes away any guesswork.

I rarely pull valve cores, I have had more issues with the valve core removal tools leaking under vacuum then it's worth to save a few minutes.

 

[TimeOrMoney]

I didn't remove no valve core or reflare any lines when I installed my Pioneer. I think sometimes the more one does the more one gets into trouble.

I think I’ll have to cut one end to not have a bunch of extra line depending on which direction I go. There is a lot of internet post on bad flares on included lines, but you know how one negative post gains traction through repetition on the internet, ha ha.

 

[chinboys]

If you make leak free joints via flaring, or swaging and change out your vacuum pump's oil, you ought to get below 500 microns in time with your existing pump.
Pressure testing the whole system with nitrogen to the working suction pressure and having it hold indicates you ought to be able to pull a vacuum.
Removal of the shraeder valves helps you get there quicker.

The key to any joint is not to over work harden it.
Yes, it helps if you have the right tools but it is essential to have the right sized diameter flare and a even better heavy duty flare nut (don't use the factory flare nuts).
Torquing it to the right specs is mandatory. I add a drop of refrigerant oil to the flare surfaces.
Or you can use Nylog in lieu of the oil for your connections.

 

[pcmeiners]

..... or use Flaretite seals, will seal at very low torque ,or at 500psi or low vacuum. I have tested these seal at 1/3 of specified torque and they seal every time; not that I do not torque to specs after I tested them.
In my opinion very cheap insurance for piece of mind. I also use a thin film of Locktite blue on flare nut threads, just behind the flare and on king valve caps. Heat is not needed to remove flare nuts or caps after it hardens.

https://www.supplyhouse.com/Rectorseal-97216-1-4-and-3-8-Flaretite-Seals-2-Pairs?utm_source=google_ad&utm_medium=shopping_neutral&utm_campaign=Shopping_Neutral_New_users&gad_source=1&gclid=CjwKCAiAzJOtBhALEiwAtwj8tnT-Qhb0-fMlQWhHvrmfVQK8Txbk8iMATNJlU2viO3hbYk58Wk8IjhoCyWsQAvD_BwE

When flaring or cutting check there are no foreign particles in the tubes when finished. You can purchase foam Qtips on Ebay for cleaning. Regular Qtips can be used but tend to leave fibers. Also blow out lineset tubes before nitrogen test or purges. Check lineset tubing for damage, had one lineset tube purposely damaged , a 8" section flattened with a hammer like object, a foot from a working end.

 

[Jackfre]

I have the Yellow jacket 60278 flaring tool. It has a depth stop. My other is the Hilmar 1838952. Do not under any circumstance use the flare from the line set company. The only reason they flare the tube is to hold the plastic cap on the end. The chances of getting a seal on the factory line set is about 0%. Get a good flaring tool and practice, practice, practice. Definitely do the nitrogen purge. These things are not “hard,” but you have to be meticulous. From experience I can tell you that it ***** BIG TIME having to go back, find and repair a leak and recharge.

 

[TimeOrMoney]

If you make leak free joints via flaring, or swaging and change out your vacuum pump's oil, you ought to get below 500 microns in time with your existing pump.
Pressure testing the whole system with nitrogen to the working suction pressure and having it hold indicates you ought to be able to pull a vacuum.
Removal of the shraeder valves helps you get there quicker.

The key to any joint is not to over work harden it.
Yes, it helps if you have the right tools but it is essential to have the right sized diameter flare and a even better heavy duty flare nut (don't use the factory flare nuts).
Torquing it to the right specs is mandatory. I add a drop of refrigerant oil to the flare surfaces.
Or you can use Nylog in lieu of the oil for your connections.

Do you mean the nuts that come with the linesets?

 

[pcmeiners]

"change out your vacuum pump's oil, you ought to get below 500 microns in time with your existing pump."

Unless your oil is contaminated with the remains of a burned out compressor or your pump does not get to a very war temperature to "boil" off water, vacuum oil will be useful for a number of installation. I installed 5 minisplits and my oil is as clear as the day I put in in. Unless it suffers from water or contamination, changing the oil does nothing.

The flare nuts on 410a system are heavier than supplied for lower gas pressure systems. Most minisplit manufactures supply the correct heavy duty nuts, but check.

If you do not buy a micron gauge and you end up with a leak, likely a couple pound of gas will cost what a gauges goes for, No less you better maintain an alternate heat source. There is a possibility the leak my take out you compressor. Buy one, use it, sell it on Ebay.
As long as you can hit 500 micron, over a extended time you are good. Personally 20 minutes is not enough, on a DIY residential system there is reason not to take longer.

 

[brewchief]

"change out your vacuum pump's oil, you ought to get below 500 microns in time with your existing pump."

Unless your oil is contaminated with the remains of a burned out compressor or your pump does not get to a very war temperature to "boil" off water, vacuum oil will be useful for a number of installation. I installed 5 minisplits and my oil is as clear as the day I put in in. Unless it suffers from water or contamination, changing the oil does nothing.

I've drained plenty of clear oil out that the pump would struggle to drop below 300 microns, a change of oil the next morning and back to normal (under 200 microns typically). Normally I will need to change mine every couple weeks in the summer installing normal split systems every day, systems that we have to flush the lineset cut the oil life down by about half.
A pump used for auto A/C is likely to not have the cleanest oil and a change before starting would be very wise.
Mini splits are an easy install as long as you use a good flare tool and make good flares, pressure test the lineset to guarantee those connections hold under both pressure and vacuum and a good deep vacuum is pulled on it. You'll never know if you have a good vacuum without a micron gauge.

 

[PWC Repair]

I installed a Sennville in my son's 5th wheel (38ft with 4 slides) over a year ago. I used my 2.5cfm HF pump. Did not remove any schraders. Did not put any kind of sealant or goop on the flares, vac pump oil only, snugged hand tight, then tightened up to next hex flat on the nuts. Been running like a champ ever since, he lives in the 5th wheel full time while trying to build a house. Your 1.5 cfm pump should work just fine. Make sure it pulls a vacuum, shut everything down and check it 30 minutes later to make sure it holds. Then let the pump sit there and run for a couple hours. Make sure it holds while shut off again.....good to go. The thing is, you're starting with new, clean, uncontaminated system parts. The only variable left is possible tiny amounts of moisture that might have gotten in. Don't overthink it. I worked for 18 years behind the counter at an HVAC supply house. I also was the guy who handled all the warranty. You'd be AMAZED at all the half assed repair work and practices on units that will still run for years and years.