In this class, Bryan teaches the Kalos techs about long line applications, accessories, and allowable line lengths. Many techs don’t fully understand the challenges of long lines. So, Bryan covers a wide range of issues and practices with long lines.
You can find the long-line piping guide we’ve used at https://carriercca.com/pdf/products_pdf/24ABB3_data.pdf.
Long lines can cause refrigerant migration. Long lines simply move more refrigerant, making migration much more likely. On top of that, a pressure drop is possible throughout longer suction lines. When you have a lot of refrigerant inside the suction line when a unit is off, it will often migrate to the condensing unit. (In a few specific cases, liquid refrigerant may migrate to the evaporator. Your unit is at risk of a flooded start when that occurs.) We also shouldn’t bury suction lines for long distances to reduce the risk of a flooded start. The ground is typically colder than the air, so the refrigerant is more likely to condense in the suction line if it is underground in a cold place.
When the system is off, you ideally want liquid refrigerant to be in the liquid line or condenser coil. Anywhere from the discharge line to the metering device is in the “safe” zone for liquid refrigerant. So, when adding liquid refrigerant to a system, you will want to add it to the liquid line so that it can vaporize in the evaporator before making it to the compressor. We NEVER want liquid in the compressor, and we only want vapor to be in the compressor while the system is running.
Straight-cool long-line A/C systems require TXVs if the line’s total length is over 50 feet. If the outside unit is above or below the indoor unit, that system will require a TXV if the line length exceeds 20 feet. TXVs are required in long-line applications because they have hard shutoff (HSO) or non-bleed valves that help prevent refrigerant migration.
A long-line A/C system may also require long-line accessories. These requirements depend on the liquid line diameter, the presence of a TXV, and where the outdoor unit is located in relation to the indoor unit (above, below, or level). The range for minimum lengths can be between 35-175 feet, depending on each of those factors. (Most of the time, we use ⅜” liquid lines with a TXV, so the minimum is usually 80 feet.)
Heat pumps with a ⅜” liquid line diameter and TXV will need long-line accessories if the lines exceed 80 feet in length (or if the vertical difference between the indoor and outdoor units exceeds 20 feet).
Pipe fittings add equivalent length, so be sure to take those into account when you measure line lengths to determine if you need long-line accessories or not.
Your allowable line lengths will be significantly greater when your condenser is above your air handler. When your condensing unit is higher, the refrigerant going to the air handler will maintain pressure more easily as it moves downhill towards the metering device. The static regain keeps the pressure drop from getting too strong.
In the case of our Carrier heat pump, we have level indoor and outdoor units situated 100 feet apart. We have a ⅜” liquid line with a TXV, so we will need a long line because the distance between the indoor and outdoor unit will exceed 80 feet in length. As a heat pump, the unit will need a standard accumulator. Based on our accessories guide, we need a compressor start assist capacitor and relay (hard start kit), crankcase heater, and hard shutoff TXV. However, we also need a liquid line solenoid valve (LLSV). These LLSVs are NOT for pump-down applications; this LLSV shuts down the liquid line when the system shuts off.
The hard start kit helps start up the compressor. The capacitance needs to be properly matched to avoid putting too much current on the start winding, so it’s a good idea to use the manufacturer’s hard start kit, not a universal one.
When it comes to installation, we start off by installing the bellyband crankcase heater. The schematics can tell you how the crankcase heater attaches to the wiring. Remember, we only want the crankcase heater to energize when the unit is OFF. When we power up the condenser ONLY, we no longer read voltage to the crankcase heater. When we shut the unit off again, our meter begins to read voltage again.
The next step is to install the hard start kit. We can test it by measuring our start amps with it in and without it in.
We install the liquid line solenoid on the liquid line. It is a normally closed valve that opens when energized. It should be installed two feet from the condenser, and the arrow on the valve must point towards the outdoor unit.
We also discuss:
Pump-down or pump-off systems
Potential relays
Capacitor windings and startup amperage
Wiring diagrams
Check out information on the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.
Read all the tech tips, take the quizzes, and find our handy calculators at https://www.hvacrschool.com/.
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Thanks Brian!!! I’ve learned a lot by watching your videos
as far as 1/4" lines, u use larger to reuse line sets with higher efficiency in the future… line sets are the largest fee wen replacement is needed… change outs are easy. same applies to your low voltage rough imo.
install a solenoid in a "buried line situation" and ur fine
nice vid, liquid is a compressors enemy, just the same as overtemp.
Brian,
Not a tech but Im trying to learn more about capacitors and you answered a lot, but i still have questions. In short, put a universal condenser fan motor and matched dual capacitor on a trane with running but too noisy, fan motor, it started and ran but it seemed to be not up to full speed and had a pulse feeling vibration. Ended up calling a local tech and he installed an additional run capacitor (small one) and it ran great . What should i have measured or looked for to have known this. This unit at daughter's house in Ga. And Im back in Tx now.
Thanks and these vidios are very informative, great job
Great videos 😜
So why can we do that when we have a 5/16" line over a 1/4"?
Finger over a straw principal been actually locked out liquid in liquid line in a substantial enough amount to adequately feed the TXV and have totally superheated gas
By the timer on the way back from the evaporator to the condensing compressor
thanks Brain ,lots of good information
Omg a shovel? 😀
So what if we don’t have a sight glass for long line as a visual will sub cooling be still accurate for a 120+ feet of line to go by ?
hey great information. the literature you read from where can i get from?
Your videos are great and very informative. I use them to prepare to train our new service techs. Really appreciated the Power In The Blood hymn reference. "Wonder working pow'r"
I like how energy kalo hes free in spirit like how he can joke with his classmates when I'm teaching I'm tend to sometimes do things wrong but not Ina manner that I can go back from like for instances for getting to put the flex seal on the cooper line before soldering so that the tech can only see what I gave to go through cutting ✂️ open to only make it look like I never cut it so he sees that it's ok forget but so he won't have too if I make sense !!!.
Tremendous class I loved it
Like the class 👍. Great explanation. Thanks for your awesome classes!
I am learning so much. 🙏 Thanks
Where's Aaron?
Finally some quality entertainment
Thanks for discussing problem and doing training. It is going to change again with new A2L's coming next year. (Long lines may disapear)
Great videos 😜
Great class. Thank you! But when are we going to learn about burying the linesets? 😄 Thats an interesting topic I am in Canada and everybody says that it is not allowed. What I read in manufacturers bulletins, they are also against it, but I see that in Florida everybody is burying them 😄 it would be great to hear your experience of burying them and how to prevent flooding.
Very nice video. Really enjoyed and learned alot.
Thanks for sharing
AC nerds101 lol 😎🤣😍👍🥶🔥😱👌
Было бы неплохо если были русские субтитры
I never clicked so fast on a YouTube video 😀
Great video!
What can we do to prevent having problems with a buried pipe?
Current is real lazy it always find the shortest path to its source.
Excellent class! I like how the instructor engages with the students and asks why. It forces them to think and formulate an answer in their head, whether or not it is correct. This feed back is important to the instructor as to how well the students are absorbing the material. Also consider that people are much more likely to remember mistakes in thought or action and therefore correct their actions in the future.
Please negative comments need not apply lol. Thank you for another great video with an awesome instructor 🙂
Power power wonder working Power 😂
That was interesting, entertaining, informative and fun. Now a question that may seem odd to a proper tech. What keeps the liquid out of the compressor during a power-on reversal like entering defrost mode? Probably stupid obvious to most but I don't know.
Your guy asked why wire the solenoid on the y call, not on the O call. I hope you answer him… most thermostats energize the O terminal when in heat mode, the entire season, the valve would remain open.
Ya missed a test. The crank case heater not only heats via the band, it also pulls watts through the compressor windings, and the motor windings ALSO produce a small amount of heat. Ya can measure the milliamperes on the common winding.
I'm glad your taking your time to teach the guys coming up in the trade. I never got that. One time I asked an owner about training. His respones was who needs training, don't you know what your doing. I asked another owner and his response was we don;t have time for training. That company had a 75 percent call back rate. Great for making overtime.