Short 11 - Superheat, The True Meaning
Вставка
- Опубліковано 23 чер 2018
- (Audio Only) In this podcast Short 11, we discuss Superheat, The True Meaning and why it is much more than "a way to set the refrigerant charge on a fixed metering device."
Superheat is the temperature of a vapor above saturation. Many people use it to set the charge on a piston or fixed orifice, but that's not its only purpose. Superheat is a much more important reading than that, and you can take that measurement at a few different places. For example, most of us measure it outside. However, to determine how the system is feeding the evaporator coil, we would take superheat at the evaporator outlet (6-14 degrees is normal for a TXV). However, superheat matters regardless of the metering device type.
Zero superheat indicates that the refrigerant is still at saturation; it is in a mixed state, not entirely vapor. So, we know that we are "overfeeding" the evaporator coil. The boiling process does not finish in the evaporator; it continues into the suction line. Overfeeding is a problem because our evaporator might not boil off all the refrigerant, and we could send liquid to the compressor. The system may be overcharged, or the evaporator load may be too low.
Excessive superheat indicates that the refrigerant is boiling off too quickly in the evaporator coil. In those cases, we are starving or underfeeding the evaporator coil. The boiling process ends too early in the evaporator coil. The system may be undercharged or have too much load on the evaporator coil.
When our superheat is within the proper range, we are feeding the evaporator coil correctly. The majority of that evaporator coil is being fed with boiling refrigerant.
Read all the tech tips, take the quizzes, and find our handy calculators at www.hvacrschool.com/
![ЛЕБЕДЕВ у ДУДЯ: муху не обманешь 😁 [Пародия]](http://i.ytimg.com/vi/E74h5fvVrqs/mqdefault.jpg)
Thanks for the great videos
So glad you made these smaller bits of subjects so we newbies don't get lost. You u are da'best!
We use subcooling and super heat all the time in the fridge process. I work for Scotsman industries, an ice machine manufacturer. Both readings are super important and helpful in determining and diagnosing problems and proper function.
Nice and simple video you made.
Sometimes it’s easier to use water as an example of super heat as most if not all are familiar with its characteristics. An example would be waters boiling point. Thus, if water is able under pressure to absorb one more degree of heat past its boiling point, we now call that one degree above boiling, super heat(ed) (steam) or vapor.
Fantastic explaination. Great examples that promote understanding why s/h is important. Using the terms under feeding and overfeeding is a great way to visualize what going on in the evap. coil.👍
This is very informative.. I would really like to hear those other podcasts on this topic as mentioned.
Thank you, Sir!
Awesome info.... it’s AMAZING how many people I know in the field who haven’t fully digested this.
I agree with that, and after 32 years I still use "Compressor Insurance"; the compressor is a VAPOR PUMP, and you want only vapor going to the compressor. A high superheat MAY be (withing design conditions) a less "aggressive" evaporator, and a low superheat MAY be (within design conditions) an indication of a more "aggressive" evaporator. The greatest transfer of heat takes place during the change of state. That's how I was taught. Within design conditions, superheat may tell us how much of the evaporator we're using. GREAT CHANNEL, THE BEST. I teach all the methods you mentioned at the outset as well to my newbies. GREAT WORK. After 30 years I pick things up from you.
A compressor doesn't pump though it compresses
Very well explained, keep up the awesome work! Thanks
Simple and to the point,, great video
So many tech dont know this.. 80% dont know VS 20% know in résidentiel. I feel like a super hero when a see this.
nice podcast keep up the amazing work
Really appreciate the informative video
MARVELOUS CHAT, appreciate it
Thanks for an awesome video
Excellent explanation
Great explanation. But I prefer the terms starved and flooded
Visualize steam in the evaporator . At least that works for me . Google super heated steam . It’s a good analogy.
Thanks for that explanation, Sir, could you please get time and explain on how a four way reverse valves operate and solenoid valve operation.
well explanation
Awesome
Superheat is the amount of heat absorbed by the refrigerant after it has fully vaporized.
Can you check super heat on a freezer if it has frost inside? If you go to the super market and go to the ice cream freezers and they working perfectly fine with lots of frost.. would you get a accurate reading if you had to put gauges on?
I'm disturbed that so few people have engaged with this video.
I'm not even in the trade and I agree with you. This seems like one of the first things you have to understand going in. As it turns out his explanation was exactly what I understood it to be.
I like your videos very much even i am not a native english speaker. Your videos are much better then the most german videos. But one question: Could you make an explanation video about subcooling? I know that the purpose of subcooling is to protect the TXV from imploding bubbles and caviation but why can a higher subcooling increase efficiency?
What i don't understand: Why is the temperature-bulb of a TxV direct behind the evaporator? Would it not be more accurate if it would be direkt before the compressor? Because that is the point, where i want to have a little bit superheat? Sometimes, especially in split-ACs there can be 10m between evaporator outlet and compressor inlet. So, if the superheat at the evaporator outlett is perfect, the superheat at the compressor inlet can be totally different.
Can you do one on Subcooling?
yeah i thought the same thng
I really like the way you explain refrigeration and air-condition systems ,am anew Hvac technician, and I would like to ask you how to acquire EPA 608 certificate? Thanks alot.
6:18 ok. When you say high super heat meaning that it's bring underfeed . But what about the subcooling.
hi, i was working on an r22 system with fixed orifice. subcooling was at 9f and my superheat was 2f. the suction temp. was about 30f. there was lots of nice cold air coming out from floor register. please help as i have no idea what the problem is. thank you for all your helpful videos.
30 is below freezing air regardless kinda sounds like u are low on “freon” hard to say with knowledge of conditions /
that makes more sence
did you just say as long as everything is kal Bitzedek? (8:52)
There is an English word of copacetic.
Thanks for that.
I’m an appliance tech, getting into HVAC, but how I could use these principals, practically for fridges? Obviously a lot of fridges aren’t worth seal system repairs, but the higher end sub zero and Vikings are. I would like to be able take this knowledge and apply it to fridges.
I asked you a question before with no reply, so if there is a better way for me to ask you, please let me know.
Thanks again for all the vids!!
You can measure suction superheat on refrigeration in the same way and it has the same significance as A/C
HVAC School would you measure at the compressor, or outlet of evaporator?
Thanks for the reply!
toneblair at the outlet of the evaporator
Wouldn’t you say that superheat in simple terms is like a buffer? Not too much or too little, just enough to keep the unit in check once it reaches the desired temperature.
So what your saying is if you have a house that's 90deg indoor and it's 95 outdoor if you show up and bam instantly throw ur gauges on and see you got 50 deg superheat and start pumping refrigerant into the system and say your unit says it wants 10deg superheat .....so you bring it down to that in the first 15 min your there ...once it the tstat starts bringing it down to 65 deg probably before that once indoor drops your going to find urself extremely overcharged ...
And u gonna start flooding the compressor.....????
So we can agree that 65 to 70 degrees is going to be a target temperature for most homes ..
.so depending on climate ..
You should stay to the high or he low side of the exceptable actuall super heat .... once u have slowly brought the home down to desired operating temp assuming that the unit is sigzed properly...
Remembering pressure and temp in refrigerants go hand and hand unit will read high pressure at high temp so u can't just say well oh they all run about 130 low side ...ull end up way over charged
@@mrfauk1948 in my area 72-76. I may be taking care of baby boomers.
No, what he is saying is the Superheat is directly related to the amount of heat being absorbed by the refrigerant (ubderfeeding = too much heat, overfeeding = not enough heat). In your scenario (90° indoor and 95° outdoor) you will never see a charging chart call for 10° of Superheat. In fact, most Superheat calculators and charts only go to 76-78° indoor wetbulb. In your scenario you need to bring the indoor conditions down to where they are on the chart first (76° IDWB) BEFORE you set the charge.
Then (76° IDWB) the Superheat will be about 29° for correct charge, so that when it does drop to 72° inside (say 68° IDWB) the Superheat will be 14° and you will not be feeding the compressor liquid.
For commercial HVAC projects VRF, DX Split etc. Check out: ua-cam.com/video/UxVfIr6trOg/v-deo.html
Superheat is to measure efficiency of a system. This is done last after the charge is calculated based on line set run and factory charge, proper installation, proper airflow and CFMs for system and equipment is properly sized for application. If any of those factors are off or a combination of factors, it will throw off your superheat reading. This I never check superheat until I know the system is sound and properly installed for said space/application.
I asked one of the new techs and he shrugged it off.
Uhm, latent heat of evaporation.
What? Did I say something wrong? That happens sometimes 😉
Max R
Now explain it....That's what good teachers do...Thank Brian another great video
Michael Madrigal. Mind your business.
HVAC School. No, you just said to ask new techs what superheat means to them so i gave my answer.
what do you do when you have a furnace problem that seemingly no tech can solve.. you go on yuo tube ..:) thats me