Trane package unit no AC
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- Опубликовано: 20 авг 2019
- Today our complaint is a restaurant that is so hot customers are walking out. I get to work through some economizer issues and learn a few things along the way.
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Nice to see I'm not the only one who educates themselves instead of ASSUMING. Thank you for being human
gotta stay humble to learn ya know- im a student everyday, just wish I had more time to study and do experiments, lol
Enthalpy economizers take into consideration "total heat" of the air based on a sliding scale computation internal to the manufactures design. They are designed to allow the air with the least amount of heat to make contact with the evaporator coil as the evaporator is designed to remove two types of heat. One is sensible heat with the other latent heat. Both represent "total heat". By using enthalpy the system uses less power because it's removing less heat so it doesn't have to work as hard. However, at an outdoor air temperature of 92 even in a dry climate the enthalpy control should have automatically removed itself from the control circuit & switched over to mechanical refrigeration.
This helped me with the unit I'm working on right this minute, appreciate it sir.
Good job bro. I see a lot of guys that just don’t understand economizers and try to just bypass them all together and only use compressors. Good work getting them that free cooling!!
I love how you took us through your thinking process. Great! Video
I live in a dry climate, so we always set up economizers for dry-bulb only. But in areas of the northwest that are more humid, we sometimes use enthalpy. However, every economizer I have seen will have a maximum dry-bulb that will override the humidity sensor, so the situation in this video cannot happen. The logic looks something like "OK to economize if enthalpy
Thank you for that. I learned a lot there. It’s rare when we have a dry enough day here in Houston for that to be a problem but good to know. Thanks again.
Thanks man great informational video..I'll keep that in mind but haven't worked on a Trane one yet
Great content loving the free infro
Now THAT was interesting. I hope reliatel and Trane was listening. Great videos!
Excellent job. Economizers are mostly a joke here in Oklahoma with the humidity on average and get bypassed a lot. This is good to know about straight temp readings and bypassing all the humidity elements that are typically the problem. That and gears jamming from dust and dirt. Economizers made me a true believer in MAU’s, something that is made for the job versus something added on.
Thank you for making this video. I am trying to understand those types of controls (economizers) a bit better in order to troubleshoot when I find them in the field. Good 👍 job.
I don’t think they only look at humidity, they look at enthalpy (btu content in the air), which is a combination of temp and humidity. The controller is trying to determine if it is easier to cool dry, hot OA or more wet, but cooler return air. It is almost always cheaper to mechanically cool dry air. Regardless of the set up, it still should have turned on mechanical cooling if it was not able to meet setpoint. My money is you have a bad sensor and a bad board. But if it works with dry bulb, and the customer doesn’t care, all good 👍 sweet vid.
You make a good point Johnathan- I'll be going back soon for there spring pm so I'll get to revisit this case and see how it's been running. Thanks for watching
Curious HVAC Guy Did the unit have a 2 stage stat?
It compares ra enthalpy against oa enthalpy. If the math works out in the enthalpy calculations, it can cool with the oa, and it's lower enthalpy. The enthalpy math at 93 degrees and low humidity, should have calculated out to DX only. Those humidity sensors are not very reliable. I have 'fixed' many trane units the same way you did. There may be a day where it is just cool enough, and dry enough to free cool, and dry bulb only might miss that. Improved reliability is what I would shoot for also. Google enthalpy calculator, and fiddle with the inputs. Good video!
@@jonathanschulz5841 I see this overlooked all the time, the installers think because its a single stage unit, that they can use a single stage stat and not wire stage two. If there is no call on y2 then the economizer will never energize the first stage compressor while it thinks its suitable to economize even if economizing alone is not enough to satisfy the setpoint. At a minimum y2 needs to be jumped to y1 or better yet use a two stage stat.
Unfortunately not everyone checks the economizer settings. One time I ran into a rooftop unit that had the economizer still collapsed inside as shipped from the factory. Very funny to find things like that.
Wow- lol I havent found that before-- just a few units that had duct work ran to the unit but no actual hole in the ductwork for it to bring in air, lol
Great Job i learn something new today
Buen trabajo aprendí algo nuevo hoy
Yo también !!! Saludos
Great Job your a great teacher, and humble thanks.
I have some units like that on a building I take care of. I m going to check and see how their economicizers are set up. Thanks for the video.
Ya learn something new everyday
Some good info right there.............
Very good information!
Humidity sensing...
Ive only ran into ambient outside type..
So thank you ,i learned something new today..
Thanks for the great information.
Bryan tyler refrigeration
Thanks for the support Joseph
Great information!! Some of these economizers are made too complicated for no good reason!!
Thanks for the video I'm sure it will help me out one day.
Great vid!
Good work as always! (get knowed up! Ha ha) hey know its a pain and time consuming. Could possible to use a Shop Vac etc., to clean the inside area? Know all before the filter. But the build up can fall into ducting below, and grow icky stuff that filter will not remove. Use long wand with a brush head. Also see you and others on the coil side not clean up the build up! Why?
Cool great video 👍
Thanks
Sir, as a new sub. I do watch others. But like watching you mire than Ted Cook of anti Diy fame.
I appreciate the support- thanks for watching
If you want the service literature for the units with the reliatel and also the older units with the UCP controls let me know. I can send you digital copies. Nice video man.
John I'd love to get a copy of anything your willing to share. Hvacrvideos@gmail.com
@@HVACRVIDEOS I'll send it your way
@@HVACRVIDEOS I'll send it your way.
@@curioushvacguy6876 sweet man. I'm happy to share it.
👍
Did you change the filters ? They look dirty itll be really great if u did
Is there a MAT setpoint Trane is going for, like Carrier has?
Have you worked on the new carrier units with a vane axial motors
Hey Luke- I have not worked on those yet, but I have seen a few pictures of them. Have you gotten to work on them?
Would be nice if they would put that trick in the manual.
Did it have a 2 stage thermostat? If y2 is energized and it is ok to economize, the unit will economize and run the compressor. Every economizer should have a 2 stage stat. We run into this a lot in freezer farms.
Curious HVAC guy basically a freezer farm is a big room where they have a bunch of -80c freezers for storing test samples. Generates a lot of heat 24/7. The economizers really work over night bringing in the “free cooling”. Another interesting thing I learned with high heat load conditions with economizers is that y3 on a jade controller is actually a timer setting. The default is 2 hours. That is definitely a must change setting for something like a freezer farm.The company I work for does mostly pharmaceutical and clean rooms in Southern California.
Serious question. If the economizer is set for free cooling at 55°F what's the need for mechanical? I just got chewed out because I noted on two new rtu installs that these units with economizers need 2 stage stats for mechanical and free cooling to maintain a mixed air temp of 55°F. So instead of getting bitched at for trying to do what I thought was right I'm setting the enthalpy sensors for 55°F hoping that anything above that (given that the enthalpy sensors are working properly) it'll just drive the outside air dampers closed, open up the return damper and just bring on mechanical.
4!RF0RC3 JU4N should not have gotten bitched at. That’s dumb logic. When the economizer, sensor, damper, etc go bad a two stage stat will turn on the mechanical cooling if the economizer doesn’t keep up (probably because it’s broken). Or what if you have a high heat load like a server or elevator room? For those rooms I typically set the Econ for 60-65deg with mechanical cooling as. Back up. Easier to cool 65deg air vs 78deg (most cases).
I have to be smarter than what I'm working on in order to be effective. Most sophisticated economizers operate proportionally. As the outside air dampers open, the return air closes. This is to keep an air volume balance and to try and maintain a temperature setpoint. Some will use enthalpy setpoint control. This should be understood already, but I'll say it anyway.. The goal is to use the air source that will require the least amount of energy to cool and when the OSAT is low enough, require nothing more than fan power turning off the refrigeration section. I mean no offense to any hvac techs, but I find that economizers often get turned off because most HVAC techs don't understand them nor are they interested in taking the time to learn how they work.
BTW, enthalpy is a value that's a combination of humidity and temperature, not humidity alone. Not to get overly technical here, but the value measures the number of water molecules and their temperature . The energy of cooling that must be applied to the coil to meet setpoint is dependant on the number of water molicules and how much the temperature needs to be changed.. The return air enthalpy is compared to the ouside air enthalpy and the lowest of the two is the best choice. modulating of the economizer on the other hand is generally done based on maintaining a temperature. Humidity is also a concern because of the energy wasted in the coil to dehumidify.
From Trane’s own recommendations, to disconnect the humidity sensors, tells me their engineering design is flawed. In my view, external temperature sensors should be the primary control of the economizers. External humidity sensors should override the economizer’s function only when outdoor relative humidity is too high for indoor comfort even though the outside temperature is, say around 50°. Cool humid air being pumped indoors WILL bring complaints❗️Thanks for your coverage of this topic❗️