Tool failure during mini split install

[gshawn]

I've been lurking around here for some time but this is my first post.

I'm DIY installing a Mitsubishi mini-split system to cool down my garage. Last year I had talked with a couple of HVAC companies in the area and was quoted $8,000 to $10,000 to install a 12K BTU system. That's not something I could afford, so I shelved the idea at the time. Then about two months ago, I found a brand new Mitsubishi unit on Facebook Marketplace for < $1000. The owners had bought the system from a family member who is a service technician, and never ended up installing it. I'm reasonably handy and I thought this would be a good opportunity for me to learn more about HVAC tech, which I've always been curious about. I realized there would be no warranty if I DIY'd the installation, but I would be saving $8,000 so this seemed like a no-brainer.

Over the last few weeks I carefully proceeded with the installation, only making progress when I felt I understood what I was doing. I read a lot of articles and probably watched 100+ training videos. I also managed to receive my EPA 608 certification. It was super interesting, and I'm very careful with my work, so I didn't mind the installation going slow. It's a pretty cool install with a nice 18K BTU unit, 35 ft of lineset and line-hide, very clean. I actually thought I would be done today, but instead ran into a huge setback.

Yesterday I vacuumed the lineset and checked that the system maintained a vacuum below 500 microns -- first for an hour, and then overnight. This morning after verifying that the vacuum held, I finally released the refrigerant into the system. I opened the lines and heard the refrigerant flow through the lineset as expected. I then replaced and tightened the line caps. Because I had removed the Schrader core from the service port (to pull a vacuum more efficiently), I needed to reinstall the valve core, make sure it didn't leak, and then power on the system.

As I began to attach the base of the core removal tool back onto the body, the top part of the tool (the part that threads onto the service port, that lets the tool body swivel) detached from the body completely! I had not yet fully reinserted the Schrader core at that point and the tool body was no longer attached to the service port. There was nothing restricting the flow of refrigerant, and it started leaking out at a VERY high rate. I was startled and it took me a few seconds to realize what was even happening. By the time I had re-removed the caps with my wrench so I could close the lines, I could tell there was no more pressure in the system.

I don't understand how this core removal tool could have failed so spectacularly. It's possible I bumped into the tool body slightly because the insertion angle was awkward, and I was wearing gloves. Perhaps the high pressure from the R-410A system was too much for the tool to handle. I'm not sure, it all happened very fast. Now with hindsight, what I should have done is release just a bit of refrigerant into the system, close off the lines, reinsert the Schrader core while pressure was low, and only then fully release the refrigerant. I just didn't anticipate that the core removal tool would basically snap in half. I'm lucky that I was wearing gloves and even though refrigerant got all over them, thankfully I was not burned.

Needless to say I'm super bummed out about this. I'm trying to figure out how to move forward and would appreciate any advice. Considering the system pressure is basically nil, is there any point in purchasing (renting?) a refrigerant recovery machine and recovery cylinder? Seems like there would be nothing left to recover. On the other hand, I'm not sure if I can proceed with evacuating the system again prior to recharging, if there are any traces of refrigerant left in the lines.

 

[gshawn]

Here is a picture of the tool that failed, for additional context. It was purchased new from Amazon.

 

[fitter30]

Don't need any reclaim equipment now. Need a accurate scale to weigh the charge in. Pull a vacuum through the valve core. Tool might not have had everything tight. If you didn't get any refrigerant burns your lucky -55.3° boiling point.

 

[pcmeiners]

Agree with Fitter30's procedure

I do not understand why people replace the core after the refrigerant release, make no sense what so ever; if the the schrader ( worth about 5 cents) leaks or strips upon replacing it, with the released gas in the system you are so royally screwed. Throughout the entire purging/vacuum/testing there is NO reason to remove the core removal tool, unless upon reinstalling the core it leaks. Attach the tool, back out the core, leave the schrader valve in the removed state in the tool. You removed it with twisting left, you reinstall twisting right.

Replace the core upon pulling the last vacuum, with the pump on, then turn off/isolate the vacuum pump and, Left out an important part, release a small amount of refrigerant, check the micron gauge,before releasing the refrigerant, Repeat BEFORE RELEASING THE REFRIGERANT.

 

[danski0224]

I do not understand why people replace the core after the refrigerant release,

It's impossible to put the core back, under vacuum, without losing some of that vacuum and bringing in outside air and moisture.

 

[Jim greengo]

I just use the old cave man Schrader valve tool anytime I replace 1,screwdriver looking tool with a slot cut in end.
Used the same tool on tires since the beginning of time.

 

[Jim greengo]

It's impossible to put the core back, under vacuum, without losing some of that vacuum and bringing in outside air and moisture.

Put the valve core back in before you pull a vacuum on the system.

 

[pcmeiners]

"It's impossible to put the core back, under vacuum"

Are you kidding? The only time you would have moisture re-enter is if the core is stripped or other wise leaking and the vacuum pump is off or disconnected.

Please explain how it is not possible to replace the core under vacuum conditions?

"Put the valve core back in before you pull a vacuum on the system."

Agree it can that way also, just slower to pull a vacuum

 

[danski0224]

Put the valve core back in before you pull a vacuum on the system.

Then it takes way longer to pull a vacuum.

Way longer.

 

[Jim greengo]

Then it takes way longer to pull a vacuum.

Way longer.

It's still faster than having a fancy tool break off in the process,throw the vacuum pump on there and let it do its thing. Hahaha

 

[danski0224]

Please explain how it is not possible to replace the core under vacuum conditions?

Have you used a core removal tool?

It's way easier to release the refrigerant and then put the Scrader core back.

 

[danski0224]

It's still faster than having a fancy tool break off in the process,throw the vacuum pump on there and let it do its thing. Hahaha

I haven't had one break yet.

But I didn't buy direct from China knockoffs from Amazon, either.

 

[Jim greengo]

I haven't had one break yet.

But I didn't buy direct from China knockoffs from Amazon, either.

I was referring to the original poster.

 

[gshawn]

I haven't had one break yet.

But I didn't buy direct from China knockoffs from Amazon, either.

Well the core removal tool is from Mastercool and it's manufactured in the USA, so not quite some cheap Chinese knockoff. I thought the brand was well regarded, but in hindsight I should have spent the extra $20 and bought the Appion tool. Lesson learned...

Appreciate all the comments so far, thanks!

 

[danski0224]

Yesterday I vacuumed the lineset and checked that the system maintained a vacuum below 500 microns -- first for an hour, and then overnight.

Vacuum test is NOT overnight.

Read the instructions. It's typically 20 minutes or less.

 

[American Locomotive]

OP, didn't you just post this exact same story recently under a different username?

Anyways, at this point you need to fully evacuate the system and find someone (or yourself) to weigh in a new charge of r410a. Not all core removal tools are rated for r410a pressures.

Are you kidding? The only time you would have moisture re-enter is if the core is stripped or other wise leaking and the vacuum pump is off or disconnected.

Please explain how it is not possible to replace the core under vacuum conditions?

VCRT hooked up to system, micron gauge hooked up to side port, vacuum pump pulling on the "straight through section" after you extract the core. Once proper vacuum is achieved, you then close the valve on the VCRT and disconnect the vacuum pump. You then screw the valve core extractor with the valve core back onto the VCRT body.

You have just introduced ambient air/moisture into the cavity the valve core is sitting in. The moment you crack that valve open to slide the core in, you will contaminate your vacuum.

Valve cores cannot be safely replaced with those tools under a vacuum. You WILL contaminate the system.

 

[whateg01]

It's impossible to put the core back, under vacuum, without losing some of that vacuum and bringing in outside air and moisture.

The point of the tool op is using is to allow the Schrader valve to be taken out or installed with a vacuumed or pressurized system. The loss of either is almost (but not quite) nil.

 

[American Locomotive]

The point of the tool op is using is to allow the Schrader valve to be taken out or installed with a vacuumed or pressurized system. The loss of either is almost (but not quite) nil.

Core removal tools are designed to help you pull a vacuum quickly. But the core must be reinserted at >0 PSI in the system, or you will pull in air and moisture into the system.

 

[danski0224]

The point of the tool op is using is to allow the Schrader valve to be taken out or installed with a vacuumed or pressurized system. The loss of either is almost (but not quite) nil.

That "almost nil" vacuum break with the core tool will ruin the vacuum you just pulled.

Hook up a micron gauge and try it

 

[gshawn]

OP, didn't you just post this exact same story recently under a different username?

Anyways, at this point you need to fully evacuate the system and find someone (or yourself) to weigh in a new charge of r410a. Not all core removal tools are rated for r410a pressures.

Oh, interesting. This is the first time I post about this issue. Do you have a link to the other thread? I'd love to read it as well.

Thanks for the guidance. Yeah I didn't realize that not all core removal tools are rated for R-410A pressures. That's something I never saw mentioned on a product listing or on videos like the one you linked above. Rookie mistake . Today I ordered the Appion core removal tool, which is rated for R-410A according to its technical brochure, and will evacuate and recharge the system when it gets here.

 

[whateg01]

That "almost nil" vacuum break with the core tool will ruin the vacuum you just pulled.

Hook up a micron gauge and try it

Yes it will but it's a much smaller pull to vacuum it down again

 

[pcmeiners]

My question is unanswered.....

Ok, you attach the core tool with a side port to the available king valve. attach a tee off core tool, one port of the tee goes to a micron gauge, the other port attached to a gauge manifold (center port), attach vacuum pump to one available low side port of the manifold, nitrogen to the high side port. The core removal tool is attached at the very beginning of the purge/vacuum/pressure test procedures and never removed until the king valves are fully opened. For that matter, as the devices/hoses are attached at the very beginning of the procedures they too are not removed until the gas is released.

Scenario

Considering this is my final vacuum after core is removed, core remaining in the core extractor....

I pull a vacuum, I turn off pump once <500 micron vacuum is achieved, verify no leaks as vacuum stabilizes and does not have micron increase; micron gauge , hoses, manifold, vacuum pump do not leak if microns do not increase over hours; the hoses I use have the hose cores removed.
With microns stabilized <500 microns and not increasing, I replace the king valve core. Slowly open king gas valve just a little. If micron increase the schrader valve is leaking, close refrigerant valve, fix issue. Now I do not normally have a faulty schrader which the normal situation, so microns do not increase over some time. At this point I open the king valves fully and remove the core tool.

Please explain how I go from a system at a stabil <500 micron vacuum, through a core tool, past my micron gauge, through my manifold all under a stable <500microns vacuum... just how does moisture/air get into my system when the entire system is always under a high vacuum throughout, and the stable micron level never increases. Must be a true miracle if moisture/air can get into a system under the conditions I described.

 

[American Locomotive]

The method you described would work, but that is not how most people use a valve core removal tool, and really not how it is intended to be used. Pulling through the side port, through that T, through hoses, through your manifold gauge set is largely defeating the purpose of the VCRT, and will dramatically slow down the vacuum.

The way a VCRT is intended to be used is as follows: Attach micron gauge directly to the side port on the VCRT. You then extract the valve core using the VCRT. You then unscrew the whole valve core extraction assembly from the VCRT (as if you were actually going to replace the schrader valve) and put it off to the side. You then hook your vacuum pump directly to end of the VCRT. No manifold gauges, no T. This gives your vacuum pump a straight through shot to the system and dramatically speeds up the process.

Once you have achieved your desired vacuum, you then close the valve on the VCRT and unhook your vacuum pump. You then screw the core removal assembly back on to the VCRT. At this point, you now have trapped quite a bit of air between the top of the core extractor and the ball valve. If you open that ball valve, you will send a slug of moist air right into the system. That is why you must charge the system with some gas at this point. You need the VCRT to be at a slightly positive pressure before you open that valve to re-insert the core.

The video I posted above shows the setup at 0:35

 

[danski0224]

There are free training videos at True Tech Tools that go through the vacuum pulling process... and other stuff.

 

[danski0224]

Yeah I didn't realize that not all core removal tools are rated for R-410A pressures.

I don't understand how your VCRT failed, despite re-reading the first post.

It reads more like operator error than tool failure. Can you post a picture of the failed tool?

There's nothing super extraordinary about R410-A pressures and pretty much any VCRT should be able to handle it.

Even the direct from China ones.

Where Appion and a couple of others are better is when a micron is used and the other lesser tools leak.

Go watch some True Tech Tools videos.

 

[pcmeiners]

"The method you described would work, but that is not how most people use a valve core removal tool, and really not how it is intended to be used."

Then most people are risking a moisture/ non compressible gas contamination. As far as how it is intended to be used, there are others who hook up as I do.
Is a core tool intended to used so moisture and non compressible could get into your system ; no one told me I should be playing Russian roulette with my system by dis-connecting/reconnecting devices on my sealed system.
Does leaving a a non leaking core tool in place add a very tiny amount of restriction, yes, does it provide and absolutely non contaminated system from moisture/non compressible, if nothing else leaks, yes. Does it cut down user errors in the startup procedure and unnecessary refrigeration losses, yes .

"through your manifold gauge set is largely defeating the purpose of the VCRT, and will dramatically slow down the vacuum."

Seriously ?, I do not have cores in my large diameter hoses, likely 6 ft of hose total, less than 50 ft of lineset... do you really believe I am dramatically slowing down my vacuum more than a few seconds due to a very tiny bit of added restriction. These are very low system volume minisplits we are talking about, not supermarkets, major warehouses or multi story commercial buildings, let get real ? As a point, I can pressurize my system with nitrogen in a split second, does restriction in vacuum act so much different ?

 

[racecougar]

I don't understand how your VCRT failed, despite re-reading the first post.

It reads more like operator error than tool failure. Can you post a picture of the failed tool?

The OP posted a photo of the failed tool in post #2.

I had issues with that same tool, OP, though I bailed on using it prior to releasing the charge, so it only cost me more vacuum time. I left a bad review for it on Amazon.

 

[American Locomotive]

Then most people are risking a moisture/ non compressible gas contamination. As far as how it is intended to be used, there are others who hook up as I do. Is a core tool intended to used so moisture and non compressible could get into your system ; no one told me I should be playing Russian roulette with my system by dis-connecting/reconnecting devices on my sealed system.

As long as you crack the service valve open for a second to let some gas into the system, there is no risk of contamination.

Seriously, I do not have cores in my large diameter hoses, likely 6 ft of hose total, less than 50 ft of lineset, do you really believe I am dramatically slowing down my vacuum more than a few seconds due to a very tiny bit of added restriction. These are very low system volume minisplits we are talking about, not supermarkets, major warehouses or multi story commercial buildings, let get real ? As a point, I can pressurize my system with nitrogen in a split second, does restriction in vacuum act so much different ?

Yes, yes it does.

It's pressure differential that causes flow across a restriction. The higher the pressure differential, the less the restriction matters. When you pressure test with nitrogen, you may have a 50-100 PSI pressure differential between the system, and the outlet of your regulator. That pressure differential can force its way through most restrictions without issue.

On the other when you're vacuuming, the system may be down to 5000 microns, but the inlet of your pump would be at 1000 microns. That's 0.0967 PSI vs. 0.0193 PSI. That's a pressure differential of 0.077 PSI. When your pressure differential is that low, EVERYTHING becomes a significant restriction. Manifold gauge sets especially.

Doing a straight-thru vacuum pull will typically result in your evac times being cut down to 1/5th of what they were, i.e., a residential system that normally took an hour to pull down, will pull down to 500 microns in about 10 minutes. It's a huge time saver.

 

[pcmeiners]

"As long as you crack the service valve open for a second to let some gas into the system, there is no risk of contamination."

Agree that will work, but I connect everything once, not removing/re-adding anything until the procedure is done.

"As a point, I can pressurize my system with nitrogen in a split second, does restriction in vacuum act so much different ?"

Point taken you are correct there is a difference, but not one that matters. At the same time I could open a valve and increase the pressure from 200 microns to zero in a split second due to large hoses, no hose cores, no king valve core, high quality manifold, small system volume. So again my closed system is not increasing my vacuum time but a tiny bit. On a large system, yes my small restriction would cause considerable vacuum time, no disagreement on that.
'

 

[American Locomotive]

Agree that will work, but I connect everything once, not removing/re-adding anything until the procedure is done.

Okay? That is not how that the vast majority use VCRTs. As shown in the video I posted.

Point taken you are correct there is a difference, but not one that matters. At the same time I could open a valve and increase the pressure from 200 microns to zero in a split second due to large hoses, no hose cores, no king valve core, high quality manifold, small system volume. So again my closed system is not increasing my vacuum time but a tiny bit. On a large system, yes my small restriction would cause considerable vacuum time, no disagreement on that.
'

The pressure difference between 200 microns and "0 vacuum" (i.e., atmopsheric pressure) is 14 PSI. That is multiple hundreds of times the pressure differential that exists between a system and your vacuum pump while under high vacuum. So that is why cracking open a valve open to air will cancel your vacuum out near instantly.

Pulling a vacuum through a manifold gauge set greatly increases evacuation time, especially getting down to the <500 micron range. This isn't even an opinion thing. It's literally fact that pulling a vacuum direct through a VCRT will increase evacuation speed 4-5x. On a small minisplit, you can pull a vacuum in like 3 minutes with a good pump.

The other huge advantage is that you eliminate a ton of leak points during evacuation with a direct connection. Every tee, every hose, all of the manifold valves, etc.. are potential leak points. This is why nearly everyone in the industry is moving to VCRTs, big vacuum hoses and fast pumps. Shoot, many techs don't even use manifolds at all anymore. They just stick their VCRT on and use wireless gauges connected to the test ports.

For someone installing a DIY mini-split with a small vacuum pump, it's probably the difference between a 30 minute evac and a 2 hour evac. Whether that's worth it to you, I can't say. For me it, it was.

 

[danski0224]

the difference between a 30 minute evac and a 2 hour evac.

This.

Or longer.

I've experienced it.

 

[Aileron]

I've done this for 40 years , from new complete grocery store systems to 1500+ ton centrifugal chillers. Wonder how they ever evacuated systems before those core tools were made? Personally, I would have left the shrader in. It's 35 ft of small line set and if it was put in right, should have been relativily dry. Sometimes you do more damage trying to overthink. Its not rocket science.

 

[pcmeiners]

Just working on a minisplit today. I decided to time a vacuum pull to 500 microns with a direct hookup from a port off a core tool, core removed, and a vacuum pump. I only had 1/4” hoses with the hose core removed, vs with a Yellow Jacket Brute manifold in between the core tool port and the vacuum pump.

I planed on timing down to 300 microns, but I was looking at a watch and it took too much attention, if I had a stop watch, and it was not 88 degrees , and not in direct sun I would have timed to lower levels.

Directly attached it took 2 minutes and 54 second to hit 500 microns

With the Yellow Jacket Brute manifold in between the hoses it took 5 minutes and 31 seconds to hit 500 microns.

More than I expected but not bad for minisplit.

 

[danski0224]

Wonder how they ever evacuated systems before those core tools were made?

Right.

Kinda like how did we illuminate stuff before electricity?

 

[Aileron]

Right.

Kinda like how did we illuminate stuff before electricity?

LOL, just like the Daiken service rep that came out and argued with me that the check valve inside the vacuum pump would stop reverse flow if someone kicks the cord out during the night. To this day,I still cannot locate that check valve.

 

[jkuro]

Don't need any reclaim equipment now. Need a accurate scale to weigh the charge in. Pull a vacuum through the valve core. Tool might not have had everything tight. If you didn't

Agree with Fitter30's procedure

I do not understand why people replace the core after the refrigerant release, make no sense what so ever; if the the schrader ( worth about 5 cents) leaks or strips upon replacing it, with the released gas in the system you are so royally screwed. Throughout the entire purging/vacuum/testing there is NO reason to remove the core removal tool, unless upon reinstalling the core it leaks. Attach the tool, back out the core, leave the schrader valve in the removed state in the tool. You removed it with twisting left, you reinstall twisting right.

Replace the core upon pulling the last vacuum, with the pump on, then turn off/isolate the vacuum pump and, Left out an important part, release a small amoun

get any refrigerant burns your lucky -55.3° boiling point.

Vacuum test is NOT overnight.

Read the instructions. It's typically 20 minutes or less.

If you have the time, what's wrong with an overnight test?

 

[danski0224]

If you have the time, what's wrong with an overnight test?

The tools/hoses/valves are not designed to hold a vacuum.

Standing vacuum test is a matter of minutes, not hours.

Your work will be ruined if you leave it in a vacuum overnight.

 

[jkuro]

The tools/hoses/valves are not designed to hold a vacuum.

Standing vacuum test is a matter of minutes, not hours.

Your work will be ruined if you leave it in a vacuum overnight.

Then you should buy better tools. I never had a problem doing a vacuum test overnight.

 

[pcmeiners]

"Your work will be ruined if you leave it in a vacuum overnight"

Please explain.... you like making statements without explaining.

 

[danski0224]

"Your work will be ruined if you leave it in a vacuum overnight"

Please explain.... you like making statements without explaining.

See below.

Then you should buy better tools. I never had a problem doing a vacuum test overnight.

How do you measure the vacuum? With a manifold gauge? How do you pull a vacuum? Through the manifold?

My analog or digital gauge can read -29" Hg but the micron gauge can read 25,000.

If you use a micron gauge, you will see that something is leaking.

And I do not (generally) buy junk tools.

There is no HVAC industry standard for "vacuum rated" with respect to tools, but it is generally accepted that Appion "vacuum rated" tools are near the top of the pile.

Everything leaks vacuum (I guess the proper phrasing would be that it admits atmosphere). The hose material, the hose crimp connections, the hose end connections, every single valve on the manifold gauge set. All of these items are primarily designed to hold PRESSURE not VACUUM.

I don't know what else to tell ya. I'm not holding your hands and doing a step by step. Go buy your own tools and do your own testing and measuring and observing. Other than watching reputable videos put out there (good luck with finding those), testing is the best way to find out why.

I have said this before. True Tech Tools has a bunch of legit videos out there on HVAC stuff, including the vacuum stuff. Their vacuum videos in particular made me change how I do things, and I thought I was doing a great job before (certainly great compared to the blow and go crowd).

There's a lot of **** out there too.