it's not.
isnt super heat measured at the coil when there is a txv and sub cooling measured at the condensing unit when there is another type of metering device such as cap tubes?
it's not.
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Not sure what your looking for with this question. Both methods can be used for diagnostics with either type system. Typically superheat is used to measure refrigerant charge of a normally operating fixed metering type system, and subcooling for expansion valve type system. Superheat can be useful for diagnosing the proper operation of an expansion valve, and subcooling can help in diagnosing a fixed metering system. Measurement can be taken from both inside and outside. This can give you an indication of refrigerant flow and possible restrictions, excessive lift, or length etc.
Superheat taken inside will help ensure proper and complete evaporation of refrigerant in the evaporator, and outside to ensure there is no liquid returning to the compressor.
Subcooling taken outside will give you an idea of the system charge and the amount of heat it can reject in regards to efficiency.
Taken inside, will help ensure there is a solid column of liquid entering the evaporator's metering device.
Subcooling combined with superheat can be a useful tool in diagnosing overcharging, undercharging, and metering restrictions.
Hope this helps. It's not everything about SC, and SH, but it's a start.
"The only true wisdom is in knowing you know nothing" Socrates
You have asked three rediculous questions with three different threads. What are you looking for?
"I am for doing good to the poor, but I differ in opinion of the means. I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it."
Benjamin Franklin, 1766
why you say ridiculouse. i am just getting in to this field and im trying to understand. there is a lot of things going on and i want to learn as fast as i can but it seems like i get differant answers from people and its hard to tell whos right.
You asked this in another thread.
The said this.i have a carrier 3 ton air handler in my attic and cant figure out how to clean the coil. there is no access what so ever. the coil is actually in the air handler. i think its a 3 year old system.
I can't see where this is even a serious question or statement. You plan on spraying a water hose inside the AH and didn't know the evap coil was supposed to be in there? Where else could it be? Then the no access statement?wow ...lots of work... i was hoping to stick a can of coil cleaner in there and spray. then hose down with water hose.
I will give a pass on the LRA/RLA question and maybe on the charging method of TXV and fixed metering device equipped systems even though a quick google search would have answered that question easily. Sorry but the whole coil post made me wonder it it wasn't serious and someone looking for laughs.
If you are serious I suggest reading some HVAC theory articles and even some youtube video's of how an A/C works before asking questions so you can get a basic understanding of what is going on and how things are generally set up. Then you can make better sense of other peoples answers even when they differ.
"I am for doing good to the poor, but I differ in opinion of the means. I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it."
Benjamin Franklin, 1766
Months ago, my instructor warned me about the amount of guys who dont understand the refrigeration cycle, or SH/SC. Also told me, if I could really get a good grasp on all that, I would be above and beyond the rest.
"I am for doing good to the poor, but I differ in opinion of the means. I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it."
Benjamin Franklin, 1766
"Better tell the sandman to stay away, because we're gonna be workin on this one all night."
"Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."
"Just get it done son."
Dad adjusted