Replydoes it have quick connects??i would think 84....what's your superheat,sub-cooling?then again you may be on right track....what are you adding per foot over 15 if you don't mind me asking....a 1/4 ounce?what tonnage is unit?
Professional Member
I have a 20 year old Amana heat pump. The condensing unit is stamped with 84 oz of R22. The A/H is stamped with 42 oz of R22.
Is the correct charge 84 + 42 = 126oz. + pipe length over 15 ft?
Or is it 84 oz + pipe length over 15 feet?
Torch Man
Professional Member*
does it have quick connects??i would think 84....what's your superheat,sub-cooling?then again you may be on right track....what are you adding per foot over 15 if you don't mind me asking....a 1/4 ounce?what tonnage is unit?
Banned
Split systems are not factory charged, they are guessed at and usually on the low side for a short run of pipe. You need to charge it properly on start-up.
Professional Member
This a rental property that I just bought. The I/D coil is clogged with dust. I am planning to recover, cut out coil, foam, then replace and charge.
The coil is so clogged I haven't bothered taking a superheat calculation yet. The unit does have quick connects, but it does NOT have valves so I have to recover. If I recover the refrigeant then I might as well charge by weight. I usually add .6 oz of freon for each foot of 3/8" liquid line over 15'.
I don't ever remember seeing an A/H with the R22 charge stamped on it. Remember this is a 20 year old system. comments?
Torch Man
Banned
Sounds like were going to mismatch coils with condensers which is fine just forget what he tag says you need to know what type of metering device. If it is a TXV then charge by subcooling if it is a piston or fixed orifice then charge by superheat the old one may have been a cap tube, don't worry the new one won't be.I wouldn't try to calculate the efrigerant chatge by weight but after you get it charged correctly you can write the correct weight down for the next time or next person.
Professional Member*
mod.&ser. #'s..???what tonnage is it????how much air you moving....didn't they use to have pre-charged line-sets???there is a difference between 3-5 ton.....on new factory charged units.all's i can say is get to it....first put in the lesser of 2 amounts....take readings...if that don't get you where you need to be then you will know that it is the sum of the 2...slowly add more to it until you are where you think your readings should be...all the while weighing your charge.this unit is 20 years old....it would be hard to say.....without tonnage.
Professional Member*
or you could weigh how much you recover..........that might give you idea.GOOD-LUCK...
Professional Member
We have the blind leading the blind here on this post as well as many other posts. When will you guys learn some applied theory and become real technicians?
Go to the "For Your Interest" area on the main page and there you will find a series of articles on both the theory behind and the practical application of properly charging systems.
Professional Member
Aww c'mon Norm, its obvious to me, I think the thingamajiggy needs to be circumvented by the whatchamacallit.
Regular Guest
well i'd just like to say if you charge a system and your pressures sub-cooling superheat are at the correct numbers for the seer system you are working on you'll do just fine
God Speed, Jim. We'll miss you - 2-26-23
What brand is the unit.
Mo Flo gave you a good answer.
You just have to remmember that if you remove 30LBS. from a 2 ton system, with 25' line set, you had a gas and go tech servicing that unit, so don't put 30lbs. back in.
Or you could start with the condensers 84ozs, and then adjust charge by superheat/or subcool as per your metering device.
Professional Member
The system is an Amana, 2 ton heat pump with a 25' line.
Torch Man
God Speed, Jim. We'll miss you - 2-26-23
Didn't know Amana used precharged line sets and coils back then.
They were common on Thermopride, GE, and Trane units in the early 80s. Still see them on mobile home units.
They kept techs from over charging new installs.
Weigh what you recover as Mo Flo said, but you might want to start out with the condensers charge and the do your fine tuning as i said above.
Professional Member*
doing the best i can do norm......troubleshooting over the net and it was getting late....and as far as that i must of been tired cause i told him 1/4 ounce per foot and not half.....anyway i have worked for numerous contractors and everyone of them had different method.....now i have my method....putting them in everyday....if you would like you could stop by and i will take you on some tours of completed jobs and you can check the charge on mine....i think you will find i know superheat and how to charge air conditioner.....if not,well then maybe you can show me how real techs. do it?Originally posted by NormChris
We have the blind leading the blind here on this post as well as many other posts. When will you guys learn some applied theory and become real technicians?
Go to the "For Your Interest" area on the main page and there you will find a series of articles on both the theory behind and the practical application of properly charging systems.
Banned
You may have lost an ( o ) somewhere,
Do you really beleive some of the things you post,some of us are posting knowledge real knowledge for the real world. Anyone can refer someone to a book, I've seen the book I've read the book and I have written some of the book.
I would bet that you beleive that a cap-tube is not a modulating metering device and that it is the same as a orifice or that a piston is like either of those two or that the metering device altogether denotes what type of charging should be used.
Professional Member
Hmm I would like to see the book you wrote.
A cap tube, oriface and piston all operate on the same principal - A pressure drop based on a specific load. The restriction is fixed. These all must be charged via superheat. A TXV gives a constant superheat once it receives a solid column of liquid which is charged by subcooling. The TXV is variable.
Professional Member
Some here are assuming things I never said and attempting to put words in my mouth. I suggest you read my articles before you try to speak for me.
And yes, purchase the book and read it!
Banned
Doc they all work on the pressure drop theory, but to say that a cap-tube and an orifice and a piston meter and modulate the same way, is just plain wrong a cap-tube is a modulating device that works much more like a txv than a piston or an orifice, GEES O MAN
Professional Member*
Personally I think everything posted so far is wrong!We should be telling him that a heat pump that is 20 years old has outlived it's lifespan & to try & repair it would be a waste of time & money!
Take your time & do it right!
Professional Member
Eddy,
I am afraid not, there is nothing remotely variable about a cap tube, it is a fixed metering device. The superheat is regulated by the restriction and the head pressure. The higher the head pressure, the more refrigerant flows just like an oriface or piston. What happens in the evaporator after the refrigerant enters it has no bearing on the cap tubes flow rate.
You do seem convinced so I am open to a logical explanation.
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