Thanks Jim I spend a hour or so a day watching your videos I really enjoy them I'm retired now since 05 but your videos make me really want to get my tools back in a van and get back to work.
Jim, in a unit with no fan running a similar system to this one one 404a (its a giant freezer) where would the second probe go? On the final outlet suction line near the txv bulb or still 10 inches down from txv? The entire suction line inside the freezer between the txv and txv temp bulb is about 50 feet of evap coil tubing. What placement would be best to fine tune this type of system?
It seems to me that Jim is actually measuring the superheat of the evaporator. Most people would put a temperature probe on the suction line right at the bulb. That would give the tail pipe temperature. The temperature of the inlet to the evaporator is derived from the PT chart, based on the liquid line pressure entering the TXV. The temperature at the bulb, measured by a thermister, thermocouple, or whatever, should be higher than the temperature of the input to the evaporator, and the difference is called the super heat. I've heard that the method of simply using two temperature sensors as Jim is doing is not the most accurate method, but "sometimes" but not all the time is accurate. I can't remember the reason exactly why this is not a good method. So if his measurement, the temperature difference of two to three degrees F is appropriate, and IS the superheat, by industry standards is kind of low. I believe that Sporlan would say about eight degrees F. I've also seen 10 plus or minus two. I installed a new TXV in a reach-in freezer a while back and measured an evaporator SH of 20F, as set by Sporlan. I had to adjust the TXV's SH adjustment to bring the SH down to about 12F. The system SH is another story, in that case the temperature probe would not be at the tailpipe (near the bulb) but would be at least six to eight inches away from the compressor on the suction line. That number can be quite a bit higher than the evaporator SH because the line from the evaporator to the compressor picks up more ambient heat. So, what do you think? Jim H.
Jim it seems to me that the evap is way to close to the comp.Excessive oil return on the suction line may trick the txv to close(hunt)..... Great video ,you're the boss
we shear our knowledge to teach another person hoping that they will be able to learn and on reality we are becoming a better person's little by little tank all of u for shearing
In a supermarket rack system refrigeration for FREEZER, does it mean our technician did not adjust superheat properly if compressor/suction is iced up? Compressor are 2 stage semi hermetic. This rack is for glass door freezer and walk in freezer.Thanks
You could spend a lot of time adjusting superheat on a close coupled system like that ( the compressor is one foot away from the evap coil.) I think also the fluke 52 could be out of calibration and also the fluke pipe clamps are in that low temp enviroment ( not insulated ) trying to get to that precise one or two degree adjustment is pretty tough! Why not just rely on the traditonal s/h method shown on the Testo's? The purpose of s/h is to make sure that all of the evap is used and limit liquid refrigerant slugging the compressor. Thanks for you making these thought proviking video's. Please keep them comming.
+gary smith as technicians we use the techniques that work for us and we feel most comfortable with, I've been using this method since the 70's, I like it the best for me, my fluke meter and clamps are pretty accurate, you know, it's hard to teach an old dog new tricks, thanks.
should all bulbs from TXV be insulated with cork take at all times. inside evap coil? i have worked on several subway coolers and both freezer and cooler txv bulbs are not insulated. please advise
Excellent video. Thanks for all your videos. Could there have been a problem with the equalizing tube in the old TXV causing the original problem? Just a thought.
Great job, but be careful with what you are calling the measurements. The difference between in and out air is delta temp, not temp difference. That is supposed to be the difference between the sat temp(coil temp) and the return(box) air temp
Why is the pipe TD only 1 on this unit and 15 on the walkin unit med temp with the three Evaporators? Does the single cir or multi circuit with a distributor make a difference?
Thanks Jim I spend a hour or so a day watching your videos I really enjoy them I'm retired now since 05 but your videos make me really want to get my tools back in a van and get back to work.
Jim always enjoy watching your videos. Thank you for your time you put into bringing these videos to us. They are greatly appreciated.
+Mike Allen No prob, thanks
I wish you would start making videos again really learned a lot from you I hope you're doing well
Allways with great satisfaction to see your videos. THANK YOU.
+ANDREASRIAL thanks
T1 goes next to the TXV bulb on outlet suction line, T2 goes about 10 inches after the TXV on a distributor tube
Thanks for mentioning where to place the temp probs, it would be helpefull to show on ur video where to place them too.
Jim, in a unit with no fan running a similar system to this one one 404a (its a giant freezer) where would the second probe go? On the final outlet suction line near the txv bulb or still 10 inches down from txv? The entire suction line inside the freezer between the txv and txv temp bulb is about 50 feet of evap coil tubing. What placement would be best to fine tune this type of system?
It seems to me that Jim is actually measuring the superheat of the evaporator. Most people would put a temperature probe on the suction line right at the bulb. That would give the tail pipe temperature. The temperature of the inlet to the evaporator is derived from the PT chart, based on the liquid line pressure entering the TXV. The temperature at the bulb, measured by a thermister, thermocouple, or whatever, should be higher than the temperature of the input to the evaporator, and the difference is called the super heat. I've heard that the method of simply using two temperature sensors as Jim is doing is not the most accurate method, but "sometimes" but not all the time is accurate. I can't remember the reason exactly why this is not a good method. So if his measurement, the temperature difference of two to three degrees F is appropriate, and IS the superheat, by industry standards is kind of low. I believe that Sporlan would say about eight degrees F. I've also seen 10 plus or minus two. I installed a new TXV in a reach-in freezer a while back and measured an evaporator SH of 20F, as set by Sporlan. I had to adjust the TXV's SH adjustment to bring the SH down to about 12F. The system SH is another story, in that case the temperature probe would not be at the tailpipe (near the bulb) but would be at least six to eight inches away from the compressor on the suction line. That number can be quite a bit higher than the evaporator SH because the line from the evaporator to the compressor picks up more ambient heat.
So, what do you think?
Jim H.
Excellent job Jim. It's fantastic to see someone take the time,to show young techs the right way to do things.
All my best.
Bobby
Another great video. I have learned a lot from you about refrigeration.
Gracias Jim por enseñarnos lo que tú hacés
Thank you so much for the wonderful explanation and patience
Thanks Jim
I'm very interested in all your videos. keep up the good work. God bless you.
+HECTOR GRANEROS You Too, thanks
Excellent txv change out and sub cooling and super heat adjustment . well done. 9/30/2022yr
Jim it seems to me that the evap is way to close to the comp.Excessive oil return on the suction line may trick the txv to close(hunt).....
Great video ,you're the boss
Awesome indeed Jim. Thanks for the Video
Another great job Jim. High praise.
Desde República Dominicana exelente
you are the man. you just inspired a young technician and i will continue to fallow keep it up
Thanks for sharing your knowledge with us Mr Jim !
Jim, I enjoy your videos. Thanks for sharing.
with the bubbles, i think u should add a bit more freon, and then i think the system will steady down better or do as much hunting
True, it will be great to have checked the subcooling before anything, I think he was low on refrigerant
we shear our knowledge to teach another person hoping that they will be able to learn
and on reality we are becoming a better person's little by little tank all of u for shearing
Thanks for the video Jim.
nice video lot of information Jim hope it stays working for you.
thanks for the video Jim.
+Ron White thanks
Great videos Jim!
thanks for the video Jim..from Philippines
great video Jim. Thanks.
Nice work Jim
Nice Job Jim.
Hey jim miss your informative videos.
My teacher, thank you
Bien
In a supermarket rack system refrigeration for FREEZER, does it mean our technician did not adjust superheat properly if compressor/suction is iced up? Compressor are 2 stage semi hermetic. This rack is for glass door freezer and walk in freezer.Thanks
You could spend a lot of time adjusting superheat on a close coupled system like that ( the compressor is one foot away from the evap coil.) I think also the fluke 52 could be out of calibration and also the fluke pipe clamps are in that low temp enviroment ( not insulated ) trying to get to that precise one or two degree adjustment is pretty tough! Why not just rely on the traditonal s/h method shown on the Testo's? The purpose of s/h is to make sure that all of the evap is used and limit liquid refrigerant slugging the compressor. Thanks for you making these thought proviking video's. Please keep them comming.
+gary smith as technicians we use the techniques that work for us and we feel most comfortable with, I've been using this method since the 70's, I like it the best for me, my fluke meter and clamps are pretty accurate, you know, it's hard to teach an old dog new tricks, thanks.
+Jim Pettinato I have to agree with you one hundred percent. Its a pleasure to watch your videos and your a good mechanic too.
+gary smith hi, whats the difference between the s/h method and and the one you use? and I gree your videos are thought provoking
Nice video jim
should all bulbs from TXV be insulated with cork take at all times. inside evap coil?
i have worked on several subway coolers and both freezer and cooler txv bulbs are not insulated.
please advise
Excellent video. Thanks for all your videos. Could there have been a problem with the equalizing tube in the old TXV causing the original problem? Just a thought.
Please explain adjustment on refrigeration’s temperature of into evap coil. Temp in , temp out. Thanks
Super heat went up, less gas in evap. T1 -25. Can you you mark the fluke 52 by gas temperature, and air evap temp. Thanks
And aren't you a bit uncomfortable with a 1.5F SH without an accumulator?
I love your videos Jim. Can't wait to start dabbling into medium and low temp. Do you also work on rack systems?
+Abel Jiminian I built a few back in the 80's, it's been a couple years since I've worked on one,
Great video Jim ....by the way what type of labeling device do you have and where can I get one !
+Terry Dowell P-Touch labeler, Office Max sells them, thanks
Where does the magic number of 1-2 degrees TD on the evap come from? Great video as always Jim.
+BenP83 an RSES meeting back around 1971, also it's in Hussman case installation literature from the 80's, thanks
Thanks Jim
Great job, but be careful with what you are calling the measurements. The difference between in and out air is delta temp, not temp difference. That is supposed to be the difference between the sat temp(coil temp) and the return(box) air temp
Jim, on a walk-in freezer what would be the temperature difference between T1 and T2 and also for a walk-in cooler.
Why is the pipe TD only 1 on this unit and 15 on the walkin unit med temp with the three Evaporators? Does the single cir or multi circuit with a distributor make a difference?
+Mike Malone for freezers I aim at 1 to 3 degrees, for medium temp 10 to 15 degrees. question 2 ...no
👍
Lower the superheat and then charge for subcool
Hi Jim is it faster to use one big hose1/2 vs two 3/8 hose for pulling vacuum ?
+Lu Wang I use 2 Appion hoses, they are fast and made better for low micron vacuums than normal gauge hoses, thanks
Where do you put the ti and t2 probes?
hi jim how are you ? when you are going to post a new video i am waiting for good bless you
What happen to Jim ?
don't know but I miss his videos
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