Pioneer Mini Split Evac and Charge / Valve Core Removal Question

danwheeler

Hi all, yesterday I completed evac and charge of my Pioneer mini-split 24k. This is the 2nd unit I've done. The first one was an 18K unit in my small detached garage. I used their vacuum in a can. That unit is still working great 1 year later. It was kind of an experiment to see how these units work.

The 24k unit I just did was for my home so I had planned to do a better job using a gauge set, VCRT and vacuum pump.

So, I get all my lines hooked up and am ready to evacuate the system but realize my VCRT is too small for the mini-split service port. Ugh... and I'm in the middle of nowhere. I think this is an R22-1/4" vs R410-5/16" thing right?

Fortunately, I did buy the 5/16ths to 1/4" adapter so I wasn't totally dead in the water. I read through the Pioneer evacuation and charging instructions again and noticed they tell you to just stick the adapter on the service port, hook your low-pressure gauge hose to the adapter and vacuum away for 15 minutes. Then make sure the gauge hits -30Hg and stays there for 5-10 minutes indicating no leaks... Then quarter turn on the refrigerant to let some out and confirm it holds pressure. If all's well, let er rip with the rest of the refrigerant.

I even called their support to confirm it wasn't necessary to remove the valve core, they said it's not needed.

1st Question:
I don't understand how you can pull a vacuum with the valve core installed... and actually with the 1/4" to 5/16" adapter, that's two valve cores inline. The valve core's whole purpose is to keep pressure from moving past it... Isn't that what a vacuum is doing? How is the vacuum pump creating any vacuum past the valve cores? I don't get it.

2nd question:
When I was done charging the system, I had to unscrew the 1/4" to 5/16" adapter and I did it as quickly as I could but got sprayed with cold refrigerant juice. Am I going to get refrigerant cancer and die? And did I let all the refrigerant out?

I never got the system fired up because my electrician installed a GFCI breaker and I've learned that inverter systems trip GFCIs. I need to go back out with a normal 20A 2-pole.

thanks,
Dan

mattmia2

The fitting that connects the the schrader valve depresses it just like on a tire. Removing the core just gives you a bigger port so everything can flow faster.

Refrigerant isn't toxic. It can freeze your skin or cause asphyxiation if enough is trapped in a small enough area.

You really need a micron gauge to tell if you have completely evacuated all of the moisture out of the system and a dry nitrogen or carbon dioxide tank and regulator to pressurize the system to test for leaks.

Their method is sort of a hope for the best method.

danwheeler

Oh man, I feel dumb... duh, the pin on the fitting keeps the valve core open.

Yeah, the manufacturer's process feels a little loosey-goosey especially when I watch all the videos about doing it right. Fingers crossed.

thanks for the help

pecmsg

Do you own a micron gauge?

danwheeler

No, and I need to go read up on how those work. But I already let the gas out of the unit into the lines though so it's a hope and a prayer from here

pecmsg

30HG is worthless. 

Sorry but are you ever licensed to deal with refrigerants?

GW

Here is the latest trend in evacuation 

your system, you definitely need a 5/16 Corey mobile tool. No adapters for evacuation, or, I guess I’ll have to see it to make an actual comment on that

Once you pull a vacuum, you isolate, and see how steady the numbers sit. One of the Golden rules is, keeping under 500 micron for 30 minutes.

Sometimes I don’t have 30 minutes. If it goes from 180 to 220 in 15 minutes, basic mathematics says it’s pretty darn good

This is a bigger system so it’s got two ports for service. But if it was just one, that’s fine, same basic thing

Old school gauge sets, they are getting a little bit long in the tooth. I think it’s been 15 years since I used a gauge set on an evacuation

 It took me a while to get used to the new Bluetooth tools, but I’m finally there. I was hooked on my Testo digital set, for eons.

ratio

The thing is that, once you're starting into a useful vacuum, there's no pressure (or suckage) to move the air, you're just waiting on the air (& other) molecules to mosey on down into the vacuum pump for no special reason. The more restriction (valve cores, ¼" hoses, etc.), the slower the evac.

GW

Corey mobile 😂 

EBEBRATT-Ed

210.8 (F) in the 2020 NEC requires all "outlets" located outdoors require GFCI protection. There is an exception for snow melting equipment. Outlets does not mean "receptacle outlets". Outlets means anything outdoors that uses electrical power, so ac and heat pump condensing units rated 50A or less are supposed to be on a GFCI circuit if your state is on the 2020 code.

Lucky for those of us in Massachusetts has an amendment that deletes this requirement in MA. At least for now

GW

Ed I’m all confused, outlets are required or no in ma? If it’s a swap we don’t bother. On a new install, some electricians say yes others say no. 

Not the first time I’ve heard opposing opinions on electrical code from electricians. 

The most famous topic is wire size for AC heat pump units. Some size of wire according to the breaker size. Other side the wire by MCA

EBEBRATT-Ed

@GW
Most electricians don't want to bother reading the code book. Although I have my electrical license, I was always a "part timer" on the electrical stuff. Because I didn't do electrical all the time when I did, I was forced to read up on things. Put me in a boiler room or on a roof top and I was pretty good that was the stuff I kept up on.

Don't put me on a gas station job


Yes, Massachusetts publishes their own MA amendments to the NEC. They adopt the NEC and then make their own changes to it.

MA has deleted the requirements for GFCI for outdoor condensers etc, not required in the current 2020 code

As for sizing wire and breakers you follow the unit nameplate on the unit

MOCP=Max overcurrent protection...read carefully some units require fuses. You can put in smaller overcurrent protection (as long as the unit will start) but not larger.

MCA=Minimum circuit amps. This is the wire size. You're better off using the 60c Collum in the code. 15 amps #14, 20amps #12, 30 amps #10 for other confusing reasons I won't go into. Again, you can use larger wire but not required


You may have a unit with 40A MOCP and 25A MCA perfectly fine 40A breaker #10 wire.

This is because it is a motor circuit. The breaker or fuses handle the inrush and starting amps. The wire is protected from overload by the thermal protection in the motors and compressor. The breaker protects against shorts and grounds.

In most wiring the wire must match the breaker size..........not in motor circuits

ratio

Right on, @EBEBRATT-Ed! I can't tell you how many electricians I've talked to about sizing feeders for condensers. Any more, I just shake my head. Not worth the argument just to make their job easier.

Good catch on noticing that some units spec fuses only & therefor effectively prohibit breakers. I've also seen units spec'd for copper only, no aluminum. Boy was Sparky sad when I pointed that out to him!

GW

Yes and thank you, my blood pressure changes sometimes when I have an electrician telling me the wire needs to be sized according to the breaker- and the MCA allows for a “smaller” wire 

semi different topic, are you familiar with the tap rule? One feed servicing two outdoor units? Fused disconnect? Sometimes I suggest this to electricians and I get little to no response

mattmia2

the tap rules wouldn't require the disconnect to be fused, right? That is why it isn't just a feeder.

EBEBRATT-Ed

Ther are two tap rules basically. 10' tap and the 25 foot tap.

Basically the code calls for the overcurrent protection at the start of the circuit

However, before bussway was made the old industrial factories they would run say a 200 amp feeder from the service out of a 200 amp fused switch or breaker. They would run this power the length of the shop through several junction boxes.

When they located there machines say a lathe they needed 30 amps for they would tap the feeder with #10s and drop down to the machine and put a 30 amp breaker or switch. The theory is the #10s if they short will blow the 200 amp main but are protected against overcurrent by the 30amp fuses or breaker. The next machine would be done the same way.

Now they are still in the code but not as widely used. Some inspectors frown on them

The 10' tap the wire you tap with can be as small a 1/10 the size of the wire you tap from. The tap conductors have to be in a raceway, conduit etc.( cant use romex for a tap) to protect the over fused conductors can't be more than 10' long and must terminate with a breaker or fused disconnect sized to protect the small wire.

25 foot tap basically same thing in a raceway, terminate in the sw or breaker to protect the small wire and the small tap wires have to be 1/3 the ampacity of the large tap wires.

I used to be friendly with one of the Springfield inspectors (long since retired). One of his pet peeves where electricians who would call him (without reading the code book first) and ask him how to do the job.


No reason you couldn't from a panel with say a 100 amp feeder large enough to feed two units fed by a 100 amp breaker and then tap off two units with two 50 amp fused switches if you wanted to or a 60 & a 40 or (3) 30 amp disconnects

However the tap wires and the fused switches would have to match(wire size=fuse size) up to the fused disconnects.

The tap wires have to be large enough for the load and the breaker or fuse cannot exceed the tap ampacity. No MCA or MOCP use on a tap

GW

(Thread officially hijacked)

Wow that’s the most tap rule info ive ever read or heard of- can’t wait for my next electrician conversation! This is NEC is suppose? Do you know what section? I’d love to feast my eyes on it 

no MCA or MOCP? How is the fuse and wire sized?

mattmia2

GW said:

\
no MCA or MOCP? How is the fuse and wire sized?

By the ampacity tables in the appendix and the voltage drop calculations.

EBEBRATT-Ed

@GW
Most of the tap rules are in 2020 NEC 240.21. I only listed the most important stuff...not all of it.

What I meant by "No MOCP or MCA" with taps is because with a tap you are attaching and undersized wire (not undersized for it's intended load) but undersized for the C/B or fuse that is upstream of the tap.

Because these tap wires are basically "over fused" for there size they must be protected by being in a raceway, EMT, Rigid, Flex, PVC etc so that the tap between the source of power and the disconnect or breaker on the load end are better protected from Physical damage. (The code used to insist on a metal raceway but have dropped that)

Because a tap is not protected at it's source the breaker or fuse it terminates in has to match the wire size.

Lets say a HVAC unit has a Mocp of 40 and an MCA of 25. So that would be a 40 am breaker and #10 wire in most cases.

If you fed this HVAC unit from a tap the same MCA of 25 applies but now because the wires are already underprotected on the supply end (by a lot) you would have to use a 30 amp breaker to protect the #10s.

The code gives and the code takes. So with a tap to this HVAC unit the question might be will it start on the smaller breaker??? Probably but maybe not. So the tap to make it work may have to be #8s with a 40 amp breaker,

Another "Tap" is basically the service entrance coming into your house. 100 amp service only requires #2 aluminum wire which is what everyone uses is only rated at 90 amps. The power company fuses on the pole are so large that the #2 aluminum are basically unprotected if they short out etc but are protected from exceeding 100 amps by the main breaker in the service


The NEC is the MINIMUM wiring standard. When we tell people we have to meet CODE they think $$$$ not understanding the code is minimum

GW

Awesome thanks I’ll have my electricians call you 😀. One guy taught me the concept, the other- I’m not sure what he knows about the tap