HVAC 056 Target Superheat for a fixed metering device
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- เผยแพร่เมื่อ 15 ต.ค. 2024
- you can download the Target superheat chart here
www.love2hvac....
the formula is Target SH=[(IDWB X 3) - ODT - 80]/2
___Indoor wetbulb F______ x3 =___________ - ___outdoor temperature_____=_______ ÷2= _________F target Superheat
Later we will be using wireless instruments to with the measurequick app to find this automatically. I first want you to have some appreciation for what the number means and why its important.
measurequick.com/
People like you is what the world needs brother, god bless you champ✊🏽🙏🏽.
Thanks a lot for this clear explanation.
In the description (formula) in upper line you wrote-80 but in lower lines you forgot this -80
I Love yr explanation. Not only Am slow learner but English my second language. But you make it easy for me to understand.
Thank you.
Same here 😂
Your the Best instructor, Thanks
Don’t stop doing such a wonderful work. Sure you’ll be rewarded and not only on money terms.
Your method of teaching in layman‘s terms and using objects in every day life that students who are academically challenged( not the book learners who learn by reading) get the basic knowledge across so they can see and grasp and understand.
I can see you understand definitely how to teach the students who don’t fall within the public education system of teaching out of the textbook 👍
Really great education man! Your one of the best if not the best at explaining! Big props!! Love your videos!! Looking forward to many more!
You should really sit down and write out a book kind of like ac service tech. I would def order your stuff to really support the channel and information you are putting out. I notice little to no ads on your videos and you deserve some return for your efforts.
I wrote a book, a school published it and claimed it as their own and screwed me out of all the work I did including building an entire online program, fusion program, complete curriculum and much more. Lesson learned, get everything in writing.
Craig is awesome, smart and a great guy. I love what he is doing and I'm honored to know him.
@@love2hvac that really sucks man. Like truly. Where im from that's violence inducing. Would love to see that book but knowing they stole it from you I wouldn't even look at it. I did support Craig. I have the book, cards, and large poster set. All quality items.
I will eventually re do it. Until then I will give out printable quick reference notes and guides.
@@love2hvac dang dude I'm so sorry you were done dirty like that... You deserve better. Thanks for everything you do.
First of all I have to say that you are the best instructor I have ever seen, thanks for all your hard work. Secondly, I have a question.
Today I was working on a r22 air-conditioning unit with a piston inside.
I took my readings inside and I had, 57 wb and 70 degrees db. My air temperature entering my odc was 60 degrees. I looked the target superheat and was 17 degrees, but I was getting 31 degrees of superheat with 150 psig at the outdoor coil and 50 psig at the indoor coil. I thought that I was underfeeding the evaporator coil probably because the outdoor temperature was too low and the pressure was not enough to push enough refrigerant through the metering device.
What I did was to use a charging jacket to increase the pressure up to 210 psig at the outdoor coil. My readings got much better with 20 degrees of superheat and 60 psig at the evaporator coil.
I just hope I didn't fooled the my readings for using the jacket.
What do you think?
Thanks a lot.
I like your teaching method
Thank you very much but i have a really important question !! I live in a dry climate which cause in low indoor wet bulb and high outdoor dry bulb. Yesterday i tried to check my 24k BTUs air conditioner via superheat chart So i start measuring. The indoor wet bulb was 60.1 F and outdoor dry bulb was 105 F which resulting a Target superheat in danger zone in the chart !! So what should i do ? Which Target superheat should i pick up for Max efficiency and compressor keep running without danger? Actual superheat was about 10F in suction line.
In that climate you need a TXV,
You can raise the temperature in the thermostat.
You can adjust the charge so the superheat is no lower than 5 at the hottest part of the day.
Thanks from Bangladesh.
Hello Mr.Ty. Talking about superheat the design of manufacture is 5-15 F degree in this point should be in freezing so l can’t imagine why the vapor line not freeze. Another question in residential A/C what is the temperature that hit the compressor should be? Thankfully.🌴🌷
Freezing and superheat are not the same.
You can have high superheat and a freezing coil.
You can have a coil not freezing and a flooded compressor.
Superheat is the difference between the actual suction line temperature and suction saturated(boiling) temperature.
You can have suction line temperature of 30 and a saturated (boiling) temperature of 20 giving you a superheat of 10. Walk in cooler is an example.
You could have a suction line temperature of 50 and a saturated (boiling) temperature of 40 giving you a superheat of 10. Example air cooling.
Both examples superheat was good one had a freezing evaporator and the other did not.
As for what superheat should be it will depend on if it's an adjustable TXV, a non adjustable TXV and you have to refer to the manufacture data, or a fixed office where you will need the target superheat chart, formula, or app.
Good morning, did you notice the light in your shop just got a little bit brighter? The reason why because the “light bulb” in my head just turned on.
Mr. Ty,
I have some confusions I want you to clear for me please,
The outdoor dry bulb usually stable it stays almost the same before and after starting the unit.
But the wet bulb temperature will change before and during running the unit,
So at what time we need to measure the wet-bulb at startup or until the system stabilized
Thanks
Great question, about every 15 minutes approximately . This is the benefit to a wireless wet bulb spectrometer. Even better the measurquick app with wireless instruments will automatically adjust all reading and more on the fly. It's a beautiful thing.
thanks, I believe, in the future, they will invent an auto adaptation control system that will optimize the subcool and superheat in real-time.
Waiting for target subcool calculation
Thanks
@@hlmbdd5566
The target subcooling for fixed orifice will be ready within the houer. The TXV (TEV) does and has been doing that for many years. It's great and simple. That video on TEV will be ready in a few days.
Very good
Awesome video. I am a little confused though. In terms of refrigeration, how does the refrigant ever to atleast 5 degrees of superheat?
If you look at the parameters in the chart, with a high outdoor temperature and a low indoor wetbulb a properly operating system would be running be running below a 5 superheat.
This means you should not run the system under those conditions.
Or install a TXV and the chart is not needed because it maintains superheat regardless of the conditions.
@@love2hvac Then i guess my question is about where you take the wet bulb temperature or what the typical wet bulb temperature would be for refrigerator. I assumed that the air entering the evaporator would be recycled in the refrigerator and that it would be under 40 degrees.
Thank you for sharing
Hello ty quick question, so on your example for Las Vegas at 7:10 I guess the best solution would be to install a txv?
Yes, a TXV is superior to a fixed orifice. It will adjust to the conditions.
Thanks!
Hello, the target SH formula is obtained empirically or it has a math proof? Is there a formula for centigrade? I know how to convert from F to C but I don`t know if 80 and division by 2 remain valid.
That is a great question! I do not know the answer, let me see if I can find it.
@@love2hvac i have asked this on hvac-talk but i'd be interested in your take on a way to translate this to refrigeration appliances
@@MTauhaA here is a pdf link for the C version
analogov.com/attachment.php?aid=399
Very helpful 👌
I think I missed the wet build dry bulb explanation ?
th-cam.com/video/cW5XA1fKaAU/w-d-xo.html
In case the unit have an TXV, is the same formula to calculate superheat?
No, the TXV's job is to control superheat regardless of the conditions. 8-12 at the coil 12-18 at the condenser depending on line length, and manufacture brand.
It needs proper air flow and the right amount of refrigerant feeding it to do this.
Is there anywhere formula and chart for celsius ?
I have been looking but I have not found one yet. I also get distracted easily.
Hi Ty, is there anyway i can compute target superheat for water cooled condenser?
I use water entering temperature in place of the outdoor temperature.
So can I use this formula on any tonnage, Freon or any SEER system?
Only for fixed orifice metering device on air cooled systems.
Most commercial systems uses the superior TXV so it won't apply.
What if I have good airflow, clean filter, condenser good subcool but low superheat?
You charge to your target superheat 1st, subcooling second.
If your suction saturated temperature is too low,
Recheck airflow with an actual measured number.
Every day I hear "airflow is good" when in fact it is not normal measured. It's almost always airflow.
Next is refrigerant restrictions, filter drier, kink in linesz clogged screen,
3rd low indoor temperature or outdoor temperature.
4th incorrect metering orifice or clog in it
5th oil logged evaporator
6th undersized evaporator coil compared tongue compressor.
@@love2hvac wow appreciate you for responding!! Can you please make a video about this? Please!!!🙏
@@love2hvac I don’t know what state you’re in but would love to sit in on your class especially Craig’s! 😃
You say 80 while pointing at 801 .....am I missing something?
Possibly, I will have to look. Dyslexia gives me problems with numbers.
@@love2hvac oh ok, gotcha, was just wondering. Sometimes the more experienced will throw out shortcuts without even realizing it.
That is not a “1” next to the 80 Ty pointed to in the formula: it is a closing bracket to match the opening bracket.
So, you have too much superheat at the end of your saturation.
(3 x wet bulb ) minus 80 + minus out side dry bulb / 2 = target super heat .
this table should be converted into a slide rule.
Some alps already implement the formula. Measuquick is my favorite
The target should also be in the installation instructions"attached" to the unit(charging chart).🤔🍺
Stay safe.
Retired(werk'n) keyboard super tech.
Wear your safety glasses
100% correct! I will be covering factory charging methods before too long.
Unless you come across old equipment that either doesn't have the information or it is faded to the point you can't read. Ty's chart seems easy to follow. I use an old trane slide rule that a tech gave to me with all the information covered in this video. Easy to use.
Ty you are the best instructor.