How to Measure Superheat and Subcooling!
Вставка
- Опубліковано 17 лип 2024
- This is 4 HVAC Scenarios on How to Measure Subcooling or Superheat to Check a Refrigerant Charge Level. There are 4 Different Refrigerant Charging Scenarios that have to do with Calculating Undercharge or Overcharge, how to know to use Superheat and How to know when to use Subcooling. I go over the methods used without any slide ruler or other tool besides the required Gauge Set and Temp Sensor. We discuss why you would need to add refrigerant or take out refrigerant! How to Measure Superheat and Subcooling! Supervision is needed by a licensed HVAC Tech before doing this as Experience and Apprenticeship garners Wisdom and Safety.
Tools Used In This Video
Yellow Jacket Refrigerant Gauge Set - amzn.to/2aenwTq
Refrigerant hoses with valves - amzn.to/2aBumVI
UEI DL379B Voltage Tester: amzn.to/3t5Cx8m
Magnet Jumpers- amzn.to/2PyKPQZ
Alligator Jumpers- amzn.to/2PxqJXn
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
Our Related Videos
• Charging R-410A Refrig...
• Checking the Charge of...
• Practice Checking the ...
• Measuring Superheat an...
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
Our HVACR Educational Books, E-Books, Workbooks, Cards, Posters, and PowerPoints:
All Our Educational Products on Our Site: www.acservicetech.com/store
All Our Educational Products on Amazon: amzn.to/48pDd82
Mini Split Book and E-Book on Our Site- www.acservicetech.com/mini-sp...
Mini Split Paperback on Amazon- amzn.to/3ytHJSs
Mini Split Paperback on TruTech Tools- www.trutechtools.com/BooksGui...
Refrigerant Charging Book and E-Book: www.acservicetech.com/ac-book
Refrigerant Charging Paperback on Amazon: amzn.to/46xTeHf
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
Our HVACR Online Resources!
Our HVAC Calculators: www.acservicetech.com/hvac-ca...
Our Newest Articles: www.acservicetech.com/articles
Try our HVAC/R Quizzes! www.acservicetech.com/quizzes
Our Other Resources: www.acservicetech.com/resources
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
Tools Used in Our Videos!
Tool Links on Our Site: www.acservicetech.com/tools
Our Tool List on Amazon: www.amazon.com/shop/acservice...
Support the Channel by purchasing tools through TruTech Tools!
Use this link www.trutechtools.com/?aff=8
Save 8% at checkout using code "acservicetech"
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
Follow Us On Our Social Media & Podcasting Channels!
Patreon: / acservicetech
Facebook: / acservicetech
Instagram: / acservicetech
X: / acservicetech
LinkedIn: / ac-service-tech-llc
Tiktok: / acservicetech
Spotify: open.spotify.com/show/74KXLz5...
Apple Podcasts: podcasts.apple.com/us/podcast...
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
⚠️ Disclaimer:
Information in this video is intended for educational purposes only. Any work related to the topics in this video should be performed by licensed technicians or by apprentices under the supervision of licensed technicians. AC Service Tech LLC is not responsible for any possible damages or injuries caused by the use or misuse of any information provided.
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
#hvacr #hvacr #hvactrainingvideos #hvactraining #hvactraining101 #acservice #acservicetech #subooling #superheat #pressure #check #temperature #gauge #manifold
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
Shop through Amazon! Your Purchases through Amazon provide a means for channels such as mine to earn advertising fees from all purchases after clicking through. Prices are the same as normal.
Tool List- www.amazon.com/shop/acservicetech
Support- www.patreon.com/acservicetech
For those that are looking for the tools used in the videos: (Linked Below)
Here is the Link for the Yellow Jacket Refrigerant Manifold Gauge Set used in the videos- amzn.to/2aenwTq
Here is a link to Refrigerant hoses with valves used in the videos- amzn.to/2aBumVI
Here is a link to the UEI DL389 Multimeter used in the videos- amzn.to/2xAdaJf
Here is a link to the Imperial 535-C Kwik Charge Vaporizer for Charging Refrigerant- amzn.to/2wFHtBW
Here is the link to the Fieldpiece ST4 Dual Temp Meter- amzn.to/2wc1ME3
Here is a link to the Digital Refrigerant Scale used in the videos- amzn.to/2b9oXYl
Here is a link for RectorSeal Bubble Gas Leak Detector amzn.to/2ckWACn
Other tool links can be found in the video description section.
ACSERVICETECH is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.
Check out other videos on the HVACR topics of interest at- ua-cam.com/channels/OZR-1IqsAer9wzlvFgb4mA.htmlplaylists?view_as=public
If you want to support the ACSERVICETECH Channel and receive more HVAC content, check out www.Patreon.com/acservicetech
I am working on air cooled chiller in which there is always alarm comes HIGH APPROACH TEMPERATURE IN EVAPORATOR...and then the unit turn off
Please help me out...
Chiller description: 70+70 tonn two circuit chiller
Charged with r134a
I've been watching all your videos and i appreciate you taking time out of your day to show us.
Thank you and glad to here that they are helping!
Good video
But camera need to move to the spots your finger pointing on to show people with no AC background to know where is this go to where !
Keep up the good work, your videos are AWSOME . Thanks again.
Glad you enjoyed it!
I did get my type 1 about 10 years ago, just to work on my own stuff. Was always fuzzy on the subcool/superheat thing, and overall check/charging. You did a great job explaining it all! I get it now. ( also happy I bought a bottle of r22 back then!)
Thanks Eddie!
thanks you for putting your time into this video.
you did a great job!
Thanks Peter le!
Nicely explained! I was having trouble understanding SH and SC but now I'm starting to understand! Thanks!
Glad to hear, thanks for letting me know! I just published for sale my 229 page e-book today at
acservicetech.com/the-book I was working on for 3 years which has all the details on the refrigeration cycle, superheat, subcooling, other charging methods and troubleshooting, thanks!
I use your videos in training classes with our techs. They are very helpful. The only comment I would add is that you must confirm clean coils and proper airflow BEFORE attempting any charge evaluation or adjustment.
I agree completely. I have been faulting my students projects and monitoring for safety. I let them experience what this looks like as the low side is below freezing but they have subcooling, if they add refrigerant all that happens is the subcooling goes up and the vapor pressure will not rise. If its a piston system all the sudden they see that now they don't have much of any superheat but the evap is still freezing. I tell them, see it just doesn't work. Once they realize this, they never make that mistake again with wanting to add refrigerant first, they visualize the problem as low air flow by their readings and know not to add. I really burns it in their memory, thanks!
Amazing video. I've watched it 5 + times and it's making a lot of sense now. So much useful info. Thanks!!
That's awesome to hear. Check out the superheat and subcooling playlist and refrigerant cycle explained playlist. I figure if I try to hit it from all the angles then it will all start to make more and more sense. Thanks and great to hear!
These videos are awesome. Thanks for the time you put into making them.
Thanks KC KC!
Awesome video. Just starting out in the business really helped . Thanks for explaining it this way I have had 4 techs try to explain this to me and I couldn't understand it until I watched your video
That's awesome to hear that it helped you!
Thank you so very much for sharing your experience and teachings.
Please keep them going 🙏
You are so welcome
If you want to support the ACSERVICETECH Channel and receive more HVAC Content, Correspond, or Collaborate on your endeavors- check out www.Patreon.com/acservicetech
All of the ACSERVICETECH Playlists- ua-cam.com/channels/OZR-1IqsAer9wzlvFgb4mA.htmlplaylists?view_as=public
Submit your email to the ACSERVICETECH email updates list at info@acservicetech.com
Thank you for your educational videos. such a science behind heating and cooling!!
Glad to help Michael Brewer!
Your videos are great👌Thanks for spreading the knowledge!
Glad you like them!
don't know where else to write this so I'll do it here, I would love to see you do some videos on pressure switches, how to test, operation , if possible replacement, causes for a trip etc. also I've recently come across a Lennox 3 ton condenser with a 24V hight temp switch right on top of the compressor. 2-24 volt wires wired in series with the high pressure switch to the contractor. also something that would make a good video. keep the great videos coming. I enjoy your work. thanks
Yes that would make a good video. I will have to wait until I get back to the shop for to do a video like that. I have had the board go bad on older condensing units with pressure switches when you don't even need a board for a single speed condensing unit!
excellent video on superheat and subcooling
Thank you!
Gald to help Carlos!
Thank you for this video. Was very educational and informative.
Glad you enjoyed it!
Awesome teaching! You broke that down very well
Thanks David!
Great great great info. Learning so much from you!!!! Thanks again👍🏼👍🏼👍🏼👍🏼👍🏼👍🏼
Thanks Luis!
PS - super quality videos! You are a great instructor.
Thanks a lot John!
Good Job. Explained a lot in just a few words. I like that.
Glad it helped!
Nice presentation bro!
Thanks Nwe!
great video with great info thanks
Thank you!
fantastic video
Thanks Green Hornet Bandit!
Great video!
Thank you!
Very informative, I am learning to fix hvac. and always wondered how they knew if it needed refrigerant. Little by little I understand just how an hvac works and hoe to dianose a unit. Thank you so much! Keep up the great work.
Thanks a lot Looney Tunes!
super u are one of the BEST!!!!!
I am glad you enjoyed it!
great content
very good job...
Thanks Robert!
Very informative video. love how you show different scenario of superheat and subcooling. My R-22 heat pump does not indicate if there's a TXV. Would it be on the evaporator label if there's one? Thanks as always
Yes, it would say on the rating plate if there is a txv installed. You could also verify by taking the door off to look if you were not sure. Thanks for the question!
When you want to increase your sub cooling because you have a txv do you Charge the system still through the vapor line? Or do you Charge through the discharge line to increase the subcooling?
Great video very informative
Thanks Suave!
AC Service Tech LLC so if the superheat is to low I would extract refrigerant right?
It would need to be recovered if the superheat was too low and the unit had a fixed orifice for air conditioning, thanks!
Great video
Thanks Fabian!
THANKS VERY INTERTED
Thanks Pedro!
Should the AC compressor be running when measuring superheat?
Awesome video.
Thanks a lot JC!
At both 6:30 and 8:50 you said the high side gauge showed 185 psig but the first one was actually much lower.
Can you do a video on the causes of low and high evaporator delta t?
I will see what I can do, thanks!
How would superheat and subcooling apply to commercial reach in coolers and freezers or walk in coolers and freezers?
Superheat is normally 25-40 degrees with the door open. After the liquid line sight is solid with the door open then you know you have subcooling with the receiver drained. If the door is closed and product is inside, you are looking for 6-8 degrees of superheat on a refrigerator roughly. Thanks
Hi, Thanks indeed for your brilliant tutorial video, but how we can get the target superheat or target sub cool temp. ?
look up "acservicetech target superheat" and acservicetech how to find subcooling"
If a residential ac split system has a txv and is checked by subcooling. After checking with gauges and temp on liquid line, do you verify you have the right subcooling by checking the superheat against it
You could check superheat just to make sure that txv is holding the superheat properly but that is the txv's job and not the refrigerant charge. Subcooling in that case would indicate the correct charge. Thanks
I have really learned a lot from your videos! Very good information! I have been wondering, will the super heat method work on an automotive A/C system? Also, would you be able to do a video describing the thermodynamics behind superheat and subcooling? I took an HVAC class when I was getting my engineering degree, however, we didn't do practical real life stuff like this. I would like to know the theory that determines why this is the way that the correct fill is determined for an A/C system. Finally, do you use your gauges across different refrigerants or do you keep a separate set for each type of refrigerant that you deal with?
Hey gearbrain91, it depends where the valves are in a car ac system also depending what rpm you are at there are variables due to speed. I believe the video that you are looking for is --- ua-cam.com/video/XscHn6GPWO0/v-deo.html ---- check out the refrigeration cycle playlist though for more step by step examples. I try to keep one set for each refrigerant especially r-134a. At worst case scenario, you could blow the oil out before use with another refrigerant but you still have oil on the sides of the hoses which you don't want to mix with other refrigerant oil systems. Any other questions just ask. Thanks!
The refrigeration cycle playlist of videos is at-- ua-cam.com/play/PLxnHR5_D2ojwbAc7K7DsjuasaDVfJeGSe.html -- but all playlists can be found on the main youtube channel. Thanks
acservicetech Thank you! I really appreciate the help and explanations!
very nice, thnx, you help me to improve my skills ;) very apreciate.
to much tech dont know this and add to much Ref or not..
Like me :S. now i will make not just a good job but a perfect job. :)
Awesome thanks GH Leader!
acservicetech i have a question, i an use this method to charge or ajust my system in winter?
or i have to bring the WB outside and DB Inside when the system is on heating? my by-energy goes to gaz after-10 -12 but its hard to me to ajust system when the temp goes under 0. thnx and advance
If we are talking about regular split systems with a heat pump outside then you can only really find the true subcooling or superheat needed during summer with a load on the building of 65 degrees or higher. The reason is because most heat pumps have an accumulator and there is no way to know how much is in this during winter. Also you now have a frosting evap coil outside. You literally have to go by either pulling the charge out and weighing back in the exact amount or just temp differences between the return ans supply air.
acservicetech ok that is what i taugh. thanks :)
24volts system on air conditioner how to check thermal Transformer
Great videos I'd learned a lot from your videos now in other cases what if there's no label with the right information?
Glad to hear! Great Question! I Usually set the subcooling for 11 or 12 if the rating plate is completely gone. You can find what refrigerant it is from the tag on the compressor or if the unit has been sitting without turning on for an hour you can tell by the pressure temp chart what refrigerant it is. Line up the pressure in the system with the average temp of the air surrounding the unit.
Well there's plenty of information except for that information
You explained how to find the target superheat by check the wet bulb on the return and outdoor temp. Is the same method used to find the subcool or is it different. If so can you explain?! Thanks!
Alex look up "acservicetech target subcooling" we also have a full article about it on our website at www.acservicetech.com/articles thanks!
On scenario 3..how are you getting 185psi? It looks like its on 155psi to me judging by the needle and its shadow.
I don't seem to understand one thing. After the refrigerant has given off its latent heat and has started its sensible cooling, its pressure must drop too right? If yes, I don't understand why we measure the pressure at the outlet and convert it to saturation temperature as the pressure at the outlet will be a tiny bit lower than the sat pressure.
what if there is a txv installed and the condenser does not have a target subcooling at the reading plate? thanks for your videos they are very helpful...
For AC our target is 8-12 degrees so I usually shoot for 11-12 if it is not there then check for 18-21 delta T across the coil, thanks
acservicetech thank for the prompt response.
Your video's are excellent. I have a very basic question, Our measurements are at the high and low side within 3", but the gauge is reading (designed/calibrated scales) "from the middle of the evap. coil", I am assuming that the length of the lines to the evap coil has been taken into consideration when the gauge dial calibration unit was manufactured. So what is the length of the lines from the outside condenser to the evap coil used as a standard (X number of feet). Wondering how the various length of line run effects the actual gauge reading? Pressure should be about the same, but temperature from a long run?
Thanks in advance
I made a video on that, - ua-cam.com/video/th0EnaSbJUw/v-deo.html
I am now taking hvac classes just started my first one so bare with me but how due find the target superheat temp or if you had to find the subcool target temp?
Here are my superheat and subcooling playlists----ua-cam.com/play/PLxnHR5_D2ojwGvhU1rseXQLJ-XBjBZMMk----https.html://ua-cam.com/play/PLxnHR5_D2ojxTcAtR_53GoY8huBcSOt0a.html
How do you properly charge a unit that has no liquid line service port?
Say a side-discharge condenser with a txv or a ductless
?
If the system is not a single or two speed then the manufacturer usually wants to charge by weight. If it is a single speed but not a port you can use two temp sensors to read subcooling. I was planning on making a video about that soon, thanks!
Good Video. I have a question. What is the basic purpose of using subcooling and/or superheat to charge a system? Is it energy efficiency? I usually charge a system just using a temp/pressure chart and then check the temp drop at the evap coil.
Thanks Mike! Do you mean the temp increase from the saturated state in the evap to the superheated vapor temp coming out? This would be done by reading the vapor pressure, converting to saturated temp on the gauge and minus-ing it from the actual temp on the vapor line. That is Superheat.Superheat is needed to check the temp rise across the evap coil from the saturated temp to the superheated vapor. This is the way to check systems with pistons or capillary tubes. This is exactly what a txv does. It monitors and adjusts to maintain the same superheat across the evap coil. When a system has a txv then you can no longer charge with superheat because the txv monitors that. You always need superheat to maintain a steady vapor and no liquid going to the compressor even when there is barely a heat load on the house. You check subcooling with systems that have a txv because in this case you can determine how much refrigerant truly is in the system as the refrigerant in liquid form is at a certain volume per the manufacturer that can be read with the temp decrease in liquid form after the saturated state(subcooling). You need a steady column of liquid feeding the txv that will not absorb heat and turn to a saturated state before it hits the txv and does a pressure drop.I hope that helps! Do you mind if I post your question and this answer in the discussion post or do you mind submitting this question again in the discussion for me to post this answer. I believe this will be of value for members of the Channel. Great Question! Thanks!
Thanks for the reply. That helped. Yes, please post the question and answer in the discussion post. I hope others benefit from it!
Glad it helped!
Great Video , however in last example in real world would you remove refrigerant from the system. Sub cooling is equal efficiency of system?
Yes correct, I was saying that subcooling is too high and refrigerant needs to be recovered from the high side and into a recovery bottle until the subcooling gets closer to the target, thanks
I like using the thermocouple from my multimeter, but how important is accuracy? It seems that if my reading is a little off and/or my Thermometer is not exact that I could be 8-10 deg off... could be disastrous. How important is accuracy, calibration and instrument selection?
Just test your sensor in an ice water mix. It should mainly be ice and the water after a five minutes should fall to 32 degrees if you get it out of the tap. Your sensor should read 32 degrees or very close and if it is off then you can get another, thanks.
Are you able to use a point and shoot laser thermal gun to measure temperature on a/c lines?
They're Not very accurate,
I found that out, putting black tape on pipe and pointing laser helped but not as good, I agree
David B. They rely on "emmisivity" of substance, a shiny surface reads as cooler than it really is
Nathan, I agree
This brand new Goodman 16 SEER 2.5 ton single stage heat pump and A/H with ECM motor with a fixed, pre installed TXV does not have a subcooling chart anywhere in the manual nor is there one anywhere on the unit. In the manual though it states to not attempt charging by subcooling if the outside temp is under 60 degrees and it says they want the subcooling to be 8 degrees F (+\-) 1-2 degrees F. Is this normal to see? Typically I find a chart in the manual or on the ratings plate.
Sometimes they are not on the rating plate but yes, make sure that it is above 70 degrees outside and inside before checking the charge with subcooling. Make sure that if the unit is microchannel then follow the manufacturers charging methods. If it is a single speed compressor on ac unit with a txv then it is usually around 11 degrees of subcooling unless microchannel, thanks
Just a question I know old school guys that check subcooling using outdoor ambient temperature minus liquid line temperature with probe is that wrong? Or is that another way just curious
That may get you close but no, we only use total superheat and subcooling, thanks!
When you say to always make sure your vapor pressure is always above 32° even when checking for subcooling. Do you mean the pressure or the saturation temp?
Sat Temp
32 is freezing point. You want to be above that so your evaporator coils doesn't freeze.
Do you think it is best to have two different sets of gauges one to do 410a and another to do r22, or is it ok to use one gauge for both refridgerants
Two gauges are certainly better so oil is not cross contaminated. I use my old set for recovering burn outs. Thanks
trukin forever it's also good because 410a is a high pressure refrigerant and normal older gauges even though they say the can go up to 400 psi they can only do 340. 410 a could blow your 22 Guage
nice
Thanks VersatileVick_media!
How do you get target Subcooling when there is no target Subcooling from Manufacture
look up "acservicetech target subcooling rating not posted" that video can be used if it is not a micro channel unit, thanks!
Are you sure that the saturated temperature of r-22 at 185 psig equates to 87 degrees Fahrenheit?
Wow you are the first person to catch that, thanks. I must have meant to say 97 but said 87 instead and didn't catch it, thanks
I saw this as well. But I have a question. When checking for subcooling do I still add 20-30 degrees on my ambient temp? Or just use what the gauges read?
Where do you find what the sub cool and super heat should be?
Target Subcooling is found on the rating plate. Target superheat is calculated using the indoor wb and outdoor db temps. Look up acservicetech target superheat thanks
if the compressor pumping less. its show same result in charging gauge as you show.but how you know its txv problem are compressor pumping less. please explain me 😐thanks sir
If the compressor is pumping less then you won't have as much subcooling. If it is a txv problem then you can see that the superheat is off. You first would need to get to the proper subcooling and then check the superheat across the evap coil, thanks
Dont you have to use the pt chart b4 getting your superheat and subcooling?
Hey F. Dorsey, the p/t chart is overlaid onto these gauges so the dial will line up the pressure on the outer ring with the sat temp on the inner ring, thanks!
Question: If the temp probe and pressure gauge are in such close proximity to each other, why is there a temp difference?
The refrigerant is no longer in sat state. Check this video out. I made it to answer this type of question- ua-cam.com/video/th0EnaSbJUw/v-deo.html
Wow that's a great video to prove exactly my question. Thanks!
Glad to help Tim!
Short answer: the gauge is calibrated to display the temperature of the refrigerant in the saturated state based on the pressure which is constant between the meter and the compressor. At the service port the refrigerant is in the vapor state so the pressure does not correlate correctly to the temperature at the port.Long answer involves Boyles law and the Ideal gas law.
what if you don't know what refrigerant is in the system. If say the data plate is not readable.
Check the sat temp and compare it to the surrounding temp when the system is equalized, compare it to p/t chart of expected refrigerants, thanks
acservicetech no sir thank you!!
What if the system only has a chart for a piston ?
If it has a txv and is a single speed unit that is not microchannel then I usually target about 11 degrees of subcooling, thanks!
Why is it that you are using super heat to adjust your refrigerant levels instead of subcooling? Is this the standard recommended in the hvac industry? Why so
Because it's a piston / orifice system
You should include wet bulb teaching in your video. Otherwise techs will be mislead.
Hey Straightoutofchiraq, here are some videos on wet bulb, thanks- ua-cam.com/video/PIYJBaOdGx4/v-deo.html -- ua-cam.com/video/bIL9BrKCujc/v-deo.html -- ua-cam.com/video/q-G7FLlzhAg/v-deo.html