Scenario of the effect of low ambient conditions. ambient around the condenser., Introductions to Solutions to running with low ambient Methods for checking or charging in low ambient conditions.
Ive been a licensed hvac contractor and an hvac instructor for a central Texas community college for many years. I just recently found you. Good job and thanks for sharing. After many years in the field I learned it’s better to work IN the air conditioning than ON the air conditioning. Thanks again.
Thanks Chris! I travel a lot but I am in west Texas near San Angelo. Are you going to theESCO, National HVAC Education conference in Las Vegas in March?
Thank you for all you do Ty.! Awesome videos to watch. I just started last week with a commercial cooking equipment and refrigeration company. And all your videos have made me an exceptional apprentice so far.!
Yes the fan runs with the condensor until I'm done charging it. The metering device will be sized to match the compressor. Each manufacturer will publish compatible metering devices for their equipment. Alternatively, I like TXV because they are sized by the ton and adjust so they are much easier to match up.
@love2hvac cool man. Is there a good way to test pressure drop across the metering device that you like if you have an inkling that there may be a plugged screen or maybe an undersized device? Sorry to bother on a Saturday night. Figure I may as well take advantage of having your ear haha. Thanks for the quick replies btw!
I remember a older service tech once saying to me that when the outdoor temp drops below 60 degrees, one should not operate a typical residential compressor. Would you say that was a good rule of thumb for recommendation?
For AC I would say 70 unless there are low ambient controls, crank case heaters and solenoid valves. Refrigeration definitely and commercial buildings may need it too. For residential it's pure luxury. Heat pumps have a complete different set of rules.
I read that with high efficiency condensers, you should add 20 and convert that temperature to pressure to get target head pressure and for standard efficiency condensers you would add 30° to get target head pressure. I noticed that you used 15° in this video. Is there that much of a difference? Thanks
I did a video n these I will post the link below 30 was standard in the 80's and High efficiency was high in the 90'S 8 SEER 24° -35° 9-10 SEER mandated 1992 = 20° -30° 11-12 SEER 15° -25° 14 - SEER mandated 2015 11° -16° 15 -16 SEER 10° -15° Variable and inverter compressors TD=NA due to varying capacities. Remember these numbers are estimates as different brands and different engineers design systems with different CFM across the condenser. here is my video on TD specifically you can skip to 7:34 ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-VzRq_36zqcg.html other resources related to condenser TD hvacrschool.com/the-pressures-look-good/ hvacrschool.com/the-5-pillars-of-residential-ac-refrigerant-circuit-diagnosis/ www.contractingbusiness.com/service/media-gallery/20870989/testing-refrigerant-charge-without-gauges
Fan speed controls is much better than fan cycling. ICM makes a nice aftermarket kit for speed control. Can't forget to also add a crank case heater as well. I know some manufacturers use one leg to keep the crank case somewhat warm. I like CCH's better though *** also low ambient conditions, dont allow for proper pressure differential for the TXV to operate properly ***
@Jason Johnson That's what your fan cycling or fan modulation does, that's its only purpose. To keep your head pressure up high enough to have a solid subcooled column of liquid to the metering device. It assures your proper pressure diff at the MD.
I personally don’t care for the headmaster control, many times i’ve had to add a fan cycle control on units so equipped over the years. I think they have problems in parts of the country where we have extremes of cold occasionally like here in the North East. I have to disagree with you though on one point, it isn’t necessary to have a ball bearing fan motor with a fan cycle control, virtually every refrigeration unit i’ve run into over the years use sleeve bearing condenser fan motors and they hold up just fine as long as they’re oiled regularly, it’s units equipped with motor controllers that vary the speed of the motor that require a ball bearing motor.
The ICP fan controllers do a much better job with swing and soft start than the old pressure switch for sure. The refrigeration fans have much less strain on them than the residential fans also. All great points thank you!
could it be said that if greater the pressure on the condenser, the greater the pressure of the liquid that goes to the TXV = the greater the amount of liquid by volume and the greater the cooling capacity? Less liquid pressure on TXV = less liquid by volume and lower cooling capacity with high SH ?
The capacity is limited by the volume displacement of the compressor. Adding more refrigerant will stack more refrigerant in the condensor flooding the condensor, reducing the amount of room available for saturated phase change. This drives the head pressure up increasing the compression ratio reducing compressor capacity. The additional liquid pressure will have a small initial opening force on the TXV but as the superheat starts to drop the TXV will apply additional closing force to maintain evaporator superheat. We need to feed the TXV enough Subcooled refrigerant so the TXV can maintain superheat for us. Extra refrigerant just puts more work on the compressor, Not enough and the TXV cant maintain superheat.
@@love2hvac Thanks for answer. Make a video next time, and explain what is the purpose of the head pressure valve and what is its significance for the autumn / winter system for low ambient temp. What exactly happens when pure vapor is fed into the system, without the effect of condensation into the liquid
The head masters were on all the elevator mechanical rooms. The first timei heard the term head master I thought it was a joke.🤣😅 Thanks for the video! 🍺🍺🍺🥃🥃🍿🏌🏻♀️ Stay safe. Retired (werk'n)keyboard super tech. Wear your safety glasses!
As a student if you understand what's going on, you'll have a lifelong skill to make money 💰👍. If you're totally confused, you will have a useless certificate of attendance👎.
