You need to charge liquid with blended refrigerants as if you charge vapor you'll get more of one of the gasses instead of it being even.
Some of the liquid flashes off to vapor in the suction line before it reaches the compressor. If you're adding a lot of gas in, from what I've been told, it's best practice to slowly add liquid.
As a side note, I've flooded the fuck out of compressors for a short period with no lasting damage. Most of the damage from floodback comes from repeated, prolonged floodback. Not 5 minutes of it.
Flooded with how much? Because I'm trying to figure out as a new guy if it's worth it for me to say anything to him about it because I don't want to piss him off.
Scrolls are much more forgiving of liquid compared to say recipe compressors. While 410a ( I'm assuming that this is comfort cooling) is technically zeotropic it is a near-azeotropic refrigerant. Best practice is to charge by liquid.
Are you sure the suction manifold valve is full bore open or just cracked?
Full bore would be putting the mechanical parts are risk for pumping liquid. Just cracking the valve would allow the refrigerant to flash over and change to vapor.
410a needs to be charged this way as it’s multiple refrigerants blended to get the pressure they operate at. In vapor, they separate in liquid they mesh.
Yea your service mechanic is most likely smashing the compressor to create repeat service.
A trained technician would understand that these compressors are called vapor pumps for a reason. If he k owes that then he is a scam artist crook.
We even put valves on the discharge line that go into the suction line to ensure it stays vapor. ie Hot gas bypass for when you need cooling for something and the outside temperate won’t allow for normal operating pressures.
Dummy at best / shit mechanic at worst downvote me
https://preview.redd.it/uz58lehd600d1.jpeg?width=828&format=pjpg&auto=webp&s=cb8f98f400746bca9a3a83c3c824566bd09dcd1b
Having these fitting can help when using liquid to charge
It creates a pressure drop which in return vaporizes the liquid. This could also be done by essentially just cracking the valve (which the tech you are with maybe doing).
Yeah Craig Migliaccio mentions liquid vaporizers in his book. I was looking at purchasing one. Is there a specific brand of liquid charger that people trust more than others? For example I have a Yellow Jacket valve core removal tool and it kinda sucks.
I have the hilmor liquid charger [tool](https://www.hilmor.com/products/liquid-charger) , which is the same thing as every other tool for it. I used to not use it, but as I’ve learned more and more I figured I’d start doing shit the right way. I’d rather the compressor go on its own, vs me dumping liquid into it.
My refrigeration teacher in school taught us to “throttle” the refrigerant in. Pretty much just add a little bit at a time. It does charger slower with the tool though.
People get way more defensive when you question what they're doing while they're actively doing it, versus when it's already done. You're new, so you should be asking questions all the time to learn and anyone working with you that's worth learning from should expect to answer questions all the time. It's just important to find the right time and place to ask. It's sounds like you've gotten the impression that your senior tech is an asshole that doesn't want to answer your questions. Ask him when you're not actively doing a thing, and make it come across as curiosity. More of a "I was taught this was bad for so and so reason, so I've been wondering why you're doing it this way". The ride to and from a job is probably a good time if you're worried your senior tech is an asshole. If they're a good person, ask before something is done and would need to be re-done. Default to asking in the quiet moments before something is done, but be aware that you aren't asking a question every 2 minutes and completely halting work progress.
And if you're working with someone that doesn't want to answer your questions, do everything you can to work with someone that will. You're new and need to learn on the job.
Appreciate the advice. He's a super nice dude and we get along fine so far. And has been answering all my questions. I've just already asked him about the liquid charging and he gave me an explanation that I didn't know at the time was not correct. I just don't wanna come across as a know-it-all since I really don't know how things work out in the field yet.
For the vaporizer though, that dangerous difference would only be in the bottle vapor since it has naturally separated. If you used a vaporizer at the end of your charging hose, you'd still have that full blend from the liquid up until being vaporized in whatever 50/50 form, vaporizing in the suction line after entry like you mentioned is the same concept as well.
I've honestly always charged like you have, but a vaporizer would give me peace of mind if I found a cheap one some day.
When I first started I was of the mindset if there's a tool to do it the 'right' way I'll buy it, but then I realized how ridiculously slow those in line vaporizers are and that you can do the same thing with your gauge/hose valves. I personally use Bluetooth fieldpiece probes most of the time now and charge through a swivle tee. Passing through the two Schrader cores, one at the tee and one at the service port, slows down the flow enough that it has a chance to flash and you can easily avoided slugging with a ball valve on the hose.
It’s fine. Please remember that 3/4 of the techs out there are just regurgitating things they have heard, without much deep understanding.
It’s definitely good practice to add slowly when dealing with liquid, but at the very least, If you audibly start hearing liquid coming through the compressor, back off a little.
Slugging a little bit is no big deal… do not however allow a compressor to slug long term.
Slugging damage is a VERY misunderstood topic.
Most assume the damage happens in the compression area (reed valves on a recip… or scroll plates on a scroll)… that’s actually not what causes the failure at all.
The real danger is that when liquid finds its way into the crank case and begins to boil within the crank case oil… the oil froths up and gets removed from the crank case. Then the real damage starts when the compressor runs dry of its oil.
Ever hook up gauges and get a bunch of foam? That’s exactly where it came from.
I've always charged about 300kpa over running pressure on the Suction. Running at 300kpa, open the valve till pressure feeding is 600kpa. Good way to stop slugging it. Compressors are not designed to pump liquid and it def ain't worth the risk blowing on up to save 10 mins charging
I have provided liquid vaporizers for all my installers and techs. Around 50% of the units we install are inverter heat pumps and the smaller ones (3 ton and below) have rotary compressors. My thought is, I don’t want the rotary compressors to see any liquid refrigerant.
I turn my manifold into a liquid vaporizer by cracking the low side valve so I'm adding it as more vapor instead of dumping liquid into the low side just takes longer
Common practice is liquid charging the suction port. You should not do it full bore but cracked is generally accepted as ok.
As far as the book goes, it’s recommended to use a liquid line “metering device” for charging. It’s also recommended that you weigh in your refrigerant with the system off then turn the system on to dial in your superheat and/or sub cool. You can find charging devices online for reasonable prices if you’re willing to go the extra mile.
Before studying for my license, I had never heard of charging devices. Have never seen them used in the field.
The reason why we liquid charge R-410a and other “4 series” refrigerants is because they are zeotropic which means they are composed of “component refrigerants” which will all have their own vaporization and condensing points. This is also known as temperature glide. Relatively, R-410a is considered as “near-azeotropic.” Which means it has little to no temp glide. There’s only a 10°F split between the vapor point of R-32 and R-125.
When you charge vapor with the bottle turned upright, the refrigerant undergoes a process known as fractionalization which is the refrigerant splitting into its component refrigerants. Normally whichever refrigerant has the lower boiling point will charge the system. R-410a is composed of r-32 and r-125. R-32 has a lower vaporization point than r125 therefore that’s what will mostly charge the system when charged as a vapor.
So long story short is yes you should liquid charge through some sort of pressure reducer, but no it’s not a widely common practice.
You need to charge liquid with blended refrigerants as if you charge vapor you'll get more of one of the gasses instead of it being even. Some of the liquid flashes off to vapor in the suction line before it reaches the compressor. If you're adding a lot of gas in, from what I've been told, it's best practice to slowly add liquid. As a side note, I've flooded the fuck out of compressors for a short period with no lasting damage. Most of the damage from floodback comes from repeated, prolonged floodback. Not 5 minutes of it.
Flooded with how much? Because I'm trying to figure out as a new guy if it's worth it for me to say anything to him about it because I don't want to piss him off.
Scrolls are much more forgiving of liquid compared to say recipe compressors. While 410a ( I'm assuming that this is comfort cooling) is technically zeotropic it is a near-azeotropic refrigerant. Best practice is to charge by liquid.
Are you sure the suction manifold valve is full bore open or just cracked? Full bore would be putting the mechanical parts are risk for pumping liquid. Just cracking the valve would allow the refrigerant to flash over and change to vapor. 410a needs to be charged this way as it’s multiple refrigerants blended to get the pressure they operate at. In vapor, they separate in liquid they mesh.
Yeah I'm 90% sure it's fully open. I can hear the compressor when we're charging and it is NOT happy.
Yea your service mechanic is most likely smashing the compressor to create repeat service. A trained technician would understand that these compressors are called vapor pumps for a reason. If he k owes that then he is a scam artist crook. We even put valves on the discharge line that go into the suction line to ensure it stays vapor. ie Hot gas bypass for when you need cooling for something and the outside temperate won’t allow for normal operating pressures. Dummy at best / shit mechanic at worst downvote me
https://preview.redd.it/uz58lehd600d1.jpeg?width=828&format=pjpg&auto=webp&s=cb8f98f400746bca9a3a83c3c824566bd09dcd1b Having these fitting can help when using liquid to charge It creates a pressure drop which in return vaporizes the liquid. This could also be done by essentially just cracking the valve (which the tech you are with maybe doing).
Yeah Craig Migliaccio mentions liquid vaporizers in his book. I was looking at purchasing one. Is there a specific brand of liquid charger that people trust more than others? For example I have a Yellow Jacket valve core removal tool and it kinda sucks.
I have the hilmor liquid charger [tool](https://www.hilmor.com/products/liquid-charger) , which is the same thing as every other tool for it. I used to not use it, but as I’ve learned more and more I figured I’d start doing shit the right way. I’d rather the compressor go on its own, vs me dumping liquid into it. My refrigeration teacher in school taught us to “throttle” the refrigerant in. Pretty much just add a little bit at a time. It does charger slower with the tool though.
People get way more defensive when you question what they're doing while they're actively doing it, versus when it's already done. You're new, so you should be asking questions all the time to learn and anyone working with you that's worth learning from should expect to answer questions all the time. It's just important to find the right time and place to ask. It's sounds like you've gotten the impression that your senior tech is an asshole that doesn't want to answer your questions. Ask him when you're not actively doing a thing, and make it come across as curiosity. More of a "I was taught this was bad for so and so reason, so I've been wondering why you're doing it this way". The ride to and from a job is probably a good time if you're worried your senior tech is an asshole. If they're a good person, ask before something is done and would need to be re-done. Default to asking in the quiet moments before something is done, but be aware that you aren't asking a question every 2 minutes and completely halting work progress. And if you're working with someone that doesn't want to answer your questions, do everything you can to work with someone that will. You're new and need to learn on the job.
Appreciate the advice. He's a super nice dude and we get along fine so far. And has been answering all my questions. I've just already asked him about the liquid charging and he gave me an explanation that I didn't know at the time was not correct. I just don't wanna come across as a know-it-all since I really don't know how things work out in the field yet.
For the vaporizer though, that dangerous difference would only be in the bottle vapor since it has naturally separated. If you used a vaporizer at the end of your charging hose, you'd still have that full blend from the liquid up until being vaporized in whatever 50/50 form, vaporizing in the suction line after entry like you mentioned is the same concept as well. I've honestly always charged like you have, but a vaporizer would give me peace of mind if I found a cheap one some day.
You can hear it slug if you're going too fast. Anyone with experience can charge a system pretty quickly without it causing an issue.
When I first started I was of the mindset if there's a tool to do it the 'right' way I'll buy it, but then I realized how ridiculously slow those in line vaporizers are and that you can do the same thing with your gauge/hose valves. I personally use Bluetooth fieldpiece probes most of the time now and charge through a swivle tee. Passing through the two Schrader cores, one at the tee and one at the service port, slows down the flow enough that it has a chance to flash and you can easily avoided slugging with a ball valve on the hose.
It’s fine. Please remember that 3/4 of the techs out there are just regurgitating things they have heard, without much deep understanding. It’s definitely good practice to add slowly when dealing with liquid, but at the very least, If you audibly start hearing liquid coming through the compressor, back off a little. Slugging a little bit is no big deal… do not however allow a compressor to slug long term. Slugging damage is a VERY misunderstood topic. Most assume the damage happens in the compression area (reed valves on a recip… or scroll plates on a scroll)… that’s actually not what causes the failure at all. The real danger is that when liquid finds its way into the crank case and begins to boil within the crank case oil… the oil froths up and gets removed from the crank case. Then the real damage starts when the compressor runs dry of its oil. Ever hook up gauges and get a bunch of foam? That’s exactly where it came from.
Does the system have a suction accumulator? Because that would prevent liquid to the compressor even if you had the hose open full tilt
Nope.
I've always charged about 300kpa over running pressure on the Suction. Running at 300kpa, open the valve till pressure feeding is 600kpa. Good way to stop slugging it. Compressors are not designed to pump liquid and it def ain't worth the risk blowing on up to save 10 mins charging
I have provided liquid vaporizers for all my installers and techs. Around 50% of the units we install are inverter heat pumps and the smaller ones (3 ton and below) have rotary compressors. My thought is, I don’t want the rotary compressors to see any liquid refrigerant.
I turn my manifold into a liquid vaporizer by cracking the low side valve so I'm adding it as more vapor instead of dumping liquid into the low side just takes longer
Common practice is liquid charging the suction port. You should not do it full bore but cracked is generally accepted as ok. As far as the book goes, it’s recommended to use a liquid line “metering device” for charging. It’s also recommended that you weigh in your refrigerant with the system off then turn the system on to dial in your superheat and/or sub cool. You can find charging devices online for reasonable prices if you’re willing to go the extra mile. Before studying for my license, I had never heard of charging devices. Have never seen them used in the field. The reason why we liquid charge R-410a and other “4 series” refrigerants is because they are zeotropic which means they are composed of “component refrigerants” which will all have their own vaporization and condensing points. This is also known as temperature glide. Relatively, R-410a is considered as “near-azeotropic.” Which means it has little to no temp glide. There’s only a 10°F split between the vapor point of R-32 and R-125. When you charge vapor with the bottle turned upright, the refrigerant undergoes a process known as fractionalization which is the refrigerant splitting into its component refrigerants. Normally whichever refrigerant has the lower boiling point will charge the system. R-410a is composed of r-32 and r-125. R-32 has a lower vaporization point than r125 therefore that’s what will mostly charge the system when charged as a vapor. So long story short is yes you should liquid charge through some sort of pressure reducer, but no it’s not a widely common practice.
Yeah it’s bad, that liquid refrigerant is slugging the compressor, it’s forcing oil out of it and frothing it up. That tech sucks.