Bryan teaches a class about what superheat signifies. Superheat is the difference between a vapor’s actual temperature and its suction saturation temperature; it lets us know how much an HVAC system feeds its evaporator coil with boiling refrigerant.
Liquid refrigerant goes into the metering device, and there needs to be enough liquid going into the metering device to achieve the desired effects of air conditioning but not so much that it floods the evaporator coil.
We want to know the evaporation temperature (the temperature at which the refrigerant boils), which we can determine with P-T charts or apps like the Danfoss Ref Tools app. A cold evaporator coil is desirable for moisture removal, but an evaporator coil that gets too cold may freeze.
We also don’t want the coil to get too cold because it could negatively affect the compression ratio by dropping the suction pressure. A cooler, lower-pressure vapor is less dense than a warmer, higher-pressure vapor, and the compressor has to do more work to raise that vapor’s temperature and pressure with each stroke or oscillation. So, you’re moving less refrigerant.
As long as a substance is still boiling as a liquid-vapor mixture, it will maintain a constant temperature as heat continues to be added to it; the temperature won’t rise or fall until boiling or condensation has been completed. Refrigerant with a 45-degree evaporation temperature will be 45 degrees as it boils, but it will go higher than 45 degrees once it has completely vaporized. That additional heat is called the superheat.
According to those rules regarding latent heat, it would stand to reason that lower superheat makes for a more efficient evaporator coil; there would be more boiling refrigerant in there. However, low superheat would put a compressor at risk of flooding if the refrigerant were to condense in the suction line. TXVs also have a minimum stable superheat that must be met. So, the efficiency of a lower superheat comes at the expense of increased flooding risk (which can lead to costly failures).
TXVs can set the superheat, and they must be charged by subcooling. However, older piston systems would require the superheat to be set, and you would need to do that with the indoor wet-bulb temperature, outdoor dry-bulb, and a superheat calculator as you charge a system.
If the superheat is too low on a TXV system, that indicates that the TXV is overfeeding the evaporator coil. On the other hand, if the superheat is too high, the TXV is likely underfeeding the evaporator coil. To prevent a failed TXV misdiagnosis, you must check several other things than the superheat; look for temperature drops across the liquid line filter-drier, airflow problems, and improper subcooling. Even when charging a system by subcooling, it helps to be aware of those conditions, the evaporation temperature, and the superheat.
On residential TXV systems, a typical rule of thumb is that the superheat should be 10 +/-5 degrees. The readings can deviate from the rule of thumb depending on things like long line sets and the location of your data point. In some cases, up to 20 degrees of superheat is acceptable in those exceptional cases where we can’t do anything about the system design, even though that may not necessarily be good for the system over the long term.
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New in the channel, really easy to understand. 👍🏻
I have worked on Sanyo mini splits that had zero degree superheat. Low ambient units with a accumulator .
Super heat is additional heat added above the saturation temperature of a fuild as show on the refrigeration tables. Your explanation seems incorrect.
Hey love you video , I was wondering if you could , share how you overcome the anxiety of meeting the customer and you following steps you created to ensure you hit all troubleshooting step within 15 mins (Aka your ah ha) moments
I'm a new subscriber seeking knowledge that I didn't find in HVAC school neither as apprentice. I have been thrown to the Wolfs in the second week. I'm studying your videos, taking notes, and trying to make it make sense to me. This stuff, superheat and subcooling hard to be explained even by technicians that have been doing it for a decade . Please do more for us the self thought people.
It's funny, the video is just 17 min. It took me 2 hours between taking notes and analysis.
Thank you
Peace ✌️
What if my wife doesn't care what Mr nipple shirt says, she can never get subcooled? It's a superheated subject.
Hi what is ideal superheat in a walk-in coolroom and walk-in freezer (both evaporators hanging in ceiling)?
Is the superheat of walk-in freezer same for multi glass door freezer in supermarkets (evaporator situated in bottom of cabinet)? Thanks
A rash!
That was fun!
I would like to know. what superheat will be . if the room temp over 95 degrees
Great info
Talk too fast. Hard to follow.
Thank you for all your videos
Doesn't the refrigerant temperature increase the longer it sits in the evaporator and does that increase in temperature also implies that is pressure goes lower and also the more it exist as gas. If this be case, it is the opposite of the high pressure side of the system.
There high pressure and temperature range it is liquid and higher pressure and temperature than that means gas again.
While in the evaporator side a different game and anamoly exist.
You are all wrong what superheat is. It is neither related to how much heat absorbed or how full anything is. If it happens to correspond to it, that is another matter.
Why it is not related to how full or how empty anything is. If it was then you will have a gauge that will show that, either in gallons or percentage of how full or empty something is.
Hah… Where is that gauge that show how full or empty it is. If it was such a thing then you would know exactly how much of it you need before you pump the crap in the system before you know how much to put. All you have is the pressure and temperature gauge. Do you not? YES OR NO.
You teach this and I just watch what you guys do and then what you say and how you describe it.
I barely made it through high school and now I know why.
It is because what I was hearing made no sense so I couldnt memorize shit.
Why this happens. Because you are too busy having learned the lingo. the lingo is more important ( it is to make you look and sound like you are something, educated).
Let me clearly explain to you what that word they invented to sound big actually is behind it all.
First it simply is in fact represented as temperature. In other words when you measure that thing, you will end up measuring a temperature you read by a gauge otherwise you would have no idea.
Don't you give a value to it. Isn't that value a temperature as some degrees? Of course you do. When you read the temperature at the so called low side of the compressor and not the temperature where it actually leaving the evaporator as whatever it maybe it is read as temperature you can see and not as heat of any sort and the pressure that goes with it. That temperature reading is not the same as the temperature you read on a thermometer hanging on your wall. Trust me it is not. But that is another story. 60 degrees on that gauge is far colder than 60 degrees that shows on that thermometer hanging on your wall. If it wasn't so. your freezer in your fridge will never be lower than 40 degrees. And everything will melt and goes with it your icecream.
Whatever you want to call it, it has been experimented that this refrigerant when it leaves the evaporator and on its way to the compressor must neither be colder or hotter than that temperature labeled superheat point. Why?
Because if it is hotter, it is tough on the compressor having to deal with that much heat and if it colder, it implies that some liquid is still present and that also is hard on the compressor to deal with. It is not because the refrigerant can not take on more or draw more heat or whatever…. Wrong. Nothing funny happens to the characteristics of the refrigerant. It won't acquire some other state of matter. It won't. It is the temperature point that makes it easier for us to deal with. It is not related to the state of change of any kind of the refrigerant.
And that becomes obvious that it is not related to whatever amount of heat was absorbed or not absorbed or contained or not contained even if it happens to correspond to it.
Don't send such refrigerant with higher or lower temperature no matter where it came from. It means don't inject your refrigerant either if you could help it into the system like as in low pressure side at that pressure and temperature you labled super whatever.
Simple as that.
The truth of it being measaured as temperature comes out. He has no choice but to say it. He himself doesn't catch it. The folks that made and designed the system knew that at this temperature which happen to be the sweet spot, it will match all the other components that go with it and it just happen to also correspond to the amount of ( mind you particular refrigerant) in the system. And it is not in terms of gallon but percentage since different size system have different actual amount of the crap in terms of gallons or whatever.
You folks, the people that started the lingo control aspect could have simply labeled superheat as ideal exist heat nothing wrong with that and the so called super cool on the condenser side. But oh no, it does not have the hollywoodish, and pompus lingo to toss around. Oh, those are too long and take up too much room to write it. Then spend infinite amount of time explaining it, memorizing it, then giving people test so they flunk the shit.
It is easy to forget anything you memorize. But try to forget something you know… try it. You may have no god dam clue what it is called whatsoever but you know it even lying in your grave if you could speak.
Mr. Einstein Mr. Einsteing, what is the speed of sound in the air.
" It is in the books, look it up" said Mr. Einstein.
You want to be a sheeple memorized fancy words….. that who are and that is what you will end up be no matter how much money you make and how big of a shot you become no matter what it maybe, whatever route or carrier or whatever you pursue.
Damn coming here really made me appreciate my manager, I knew most of not all of this info.
Not as in depth naturally 😅
Wish in one hand and shit in the other and see which one fills up first🤣 that’s what our grandfathers said. Lol
Great as always. Sometimes I have to replay to understand it better. He speaks really fast or is my English too slow? 🤔
Helpful video. Tech for 13 years but sometimes you get foggy about the principles learned in AC night School. Great video.
great video. nipples are a bit distracting tho
can anyone tell me where to find replacement acetylene regulators " just the one " thanks
Hi am from mauritius and like your video pls can you explain me how to flush a dvms samsung system and mcu with flushing agent pls answer me thks in advance
Hi sr How i can contac the school i will like to take the class
Outstanding information 👏
what's CTOA stands for?
Chinese Tractor Owners Association?
Thanks!
As an ASE certified auto technician who jumped ship to do residential HVAC I'm glad to see I'm not losing my mind, I keep saying that basically were moving energy/heat, laws of thermodynamics state basically hot wants to go somewhere cold or technically it wants to calm down lol, every HVAC tech I've worked for and with since my switch in careers says I'm wrong or don't get it, but he just totally redeemed me lol, your just moving heat one way or another especially with a heat pump, furnace just makes its own heat but still moves it lol. I noticed that alot of HVAC techs are stuck up and cocky, meanwhile I just want to talk shop and openly yet fairly compare equipment and setups but always get slack for being "a greasy car mechanic" . Love the videos!
Some system sees are used to use a capillary tube to meter the refrigerant which I believe is different than the piston system you describe here.
Asbestos exposure would be a little more analogous than smoking for a long term damage example. If you're trying to stay with a lung analogy.
Cool 😁👍
was BT in the navy, when ships had boilers and steam turbines. super heated steam was a point where there was no water vapor left. it was super heated to point where it was a hot steam gas. used to turn the steam turbines so the turbine fans wouldn't be contaminated. the pressure in the boilers were 650 psi and some were 1250 psi. that was in a 8" steam pipe.
I had a job working with Thermal engineer's for about 9 years , it was a very interesting job building there ideas , I picked up on how refrigerant and refrigerant systems worked , we would build , we would test , then start again , thanks .
Superheat is the heat picked up after a liquid completely evaporates and becomes a gas. Nothing more, nothing less. Knowing you have some superheat before the compressor is important so you don't have liquid or partial liquid going into the compressor. Liquid cannot be compressed without damaging the compressor. So having some measurable superheat is a good thing.
I've been doing HVAC for 32 years and I also teach it. This is one of the best explanations of superheat I've seen. Great job! I've found through teaching about units from 2 tons to 1000 tons, too many techs do not really understand the refrigeration system, how a metering device works, and what superheat and subcooling is and how it can effect system ops. Most techs think a/c units add cooling to a space but that is not true. They actually remove heat and move it to then release it via air, water. or earth's temps.
Hey brayan great video man, I watching all the way from roatan honduras, keep the good work up.
Wish in one hand, crap in the other… see which one fills up quicker. That’s the statement. Good videos. 👍
Terminology is new to me. Its alot like taking a housing inspection class. Way to much info in a short time. Its basically an info class for those who have general knowaledge… oops not me
Superheat is the temperature difference between the actual vapor temperature and the saturated vapor temperature at a given pressure. Superheat is used as an indicator of how much heat is being added to or removed from a refrigerant. When superheat is low, it indicates that the refrigerant is not reaching its saturation point, which may be due to a restriction in the system.
You have gotten better at your videos!! I haven’t been around for a long time because I basically work on all chiller system now. However chillers use superheat and without proper superheat my approach will be way out for wack on a chiller. I like this video!
Thanks for helping the HVAC industry and giving a damn.
Thanks Bryan , kindly please make one video on inverter mini split system because it's challenging to maintain superheat. Waiting for your favorable reply.
Very good teacher.