Charging by weight question

[torch man]

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

[mo-flo]

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?

[fat eddy]

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.

[torch man]

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

[fat eddy]

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.

[mo-flo]

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.

[mo-flo]

or you could weigh how much you recover..........that might give you idea.GOOD-LUCK...

[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.

[docholiday]

Aww c'mon Norm, its obvious to me, I think the thingamajiggy needs to be circumvented by the whatchamacallit.

[dmoneyc22]

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

[beenthere]

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.

[torch man]

The system is an Amana, 2 ton heat pump with a 25' line.

Torch Man

[beenthere]

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.

[mo-flo]

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.

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?

[fat eddy]

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.

[docholiday]

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.

[NormChris]

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!

[fat eddy]

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

[markwolf]

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!

[docholiday]

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.

[NormChris]

Originally posted by lmtd

Originally posted by fat eddy
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

Every now and then one comes across a post that catches an eye.

The only problem that exist with your post is if you actually think any of it was more than comedy.

If this is your thought on how the refrigeration cycle actually works, I pity your clients and you owe them a huge thanks for allowing you to hack on their units.

Amazing is it not LMTD? We have people posting their ignorance without any shame who openly claim to be service managers. When they should be asking questions, they are posting their ignorance. I have been waiting to allow them to post a little more and hang themselves before I post the way it really works.

Norm

[fat eddy]

Hi Norm,

Please go ahead and hang me first, then I will not only tell you how it works I will also supply you with the porper documentation to verify it.

( just for you info I have won a lot of money on this question)

[NormChris]

Originally posted by lmtd
Oh Norm,

You got a live one here. You KNOW I want to take this one on and act like an ass while doing so, but I will let you instead as you will remain far more professional than I.

Hey fat boy, you're about to get handed your hat and expose just how clueless you really are sir.

LMAO gonna provide documentation on cap tubes lmgdao, have fun Norm!

In the interest of remaining professional I will allow him the dignity of explaining himself since he is the one who made the claims regarding how a cap tube really works.

Who knows, perhaps it is all a matter of semantics.

[fat eddy]

Come on Norm,

Forget the professional BS, go ahead and hang me you said ya could. I think you are scurrying to read up on it between posts. go ahed hang me high, and please don't worry about my dignity.Let me give ya a little common sense clue that you all may be able to relate to before you jump the gun and make fools of yourselves. If a cap tube were a fixed orifice don't you think they would of just used a fixed orifice ? Knaw on that a little while, as yur doing yur google search for "CAP TUBES REASON FOR BEING"

[Boss]

Keep it friendly, polite and educational guys. Leave the egos at the door.

Thanks

Boss

[NormChris]

Sure Boss, I have no interest in a flame war. Neither LMTD nor I have anything to prove. We have already established our credibility here.

I'll let it go as hard as it is to do so. Knowing fat eddy he will continue to post and folks will catch on soon enough without LMTD and I making a point of it.

Norm

[fat eddy]

Hold on,

I'm just having a little fun to, but please don't leave without answering. Don't tell me I'm wrong if you can't tell me what is right.If I didn't know any better I would say you are looking for an easy way out. If you don't post in ten minutes with your version then I win and I will drop it.

[fat eddy]

OK ten more minutes, I'm going outside to smoke when I come in I'm claiming victory.

[docholiday]

Lol

[fat eddy]

Have you ever hear the song by Queen, it goes something like this

And another one down and another one down and another one bites the dust.

Heres another little clue that may help you on your search for the truth about cap-tubes, which travels faster vapor or liquid ? if one of these travels faster do you think that there would be a potential for that cap-tube to modulate if the balance of liquid and vapor were to change ?

[dpatty]

yep if you can't show your docs just claim victory while he is trying to figure out how to dumb it down for you

[Edited by dpatty on 02-14-2005 at 10:12 PM]

[docholiday]

Hmmm sounds extremely inefficient to start the process of absorbing heat in a place where it does no good. Isnt that the process of cooling? Absorb heat by the changing of state IN the evaportator? Why would we change state prior to entering the evap? Changing the state of gas has very little effect since it requires very little heat to raise the temperature.

[fat eddy]

Hi Patty,

Yoget an A+ for catching your error then repairing it before you got a callback. Very Good, Very Good,

Original spelling of DOCS was DACS

[dpatty]

I turned all red faced when I noticed that

You might want to fix that first word. Wouldn't want anyone thinking your ignorant

[Edited by dpatty on 02-14-2005 at 10:52 PM]

[fat eddy]

Doc,

Its not a place to change state its called the bubble length. For documentation just open up any RSES SAMS manual or consult the manufacturer of the thing, and you will find the correct definition of a cap-tube, Vapor and liquid travel through the tube in varying proportions according to the load on the evaporator that is why the length of a cap-tube is so critical it is not the same metering device if you have the wrong length or size. This is simple stuff simply overlooked.There is no other definitin and no comparison to an orifice or a piston now I'm going to assume that everyone knows the difference between an orifice and a piston.

Oh yeah vapor travels slower restricts fluid,less liquid less cooling effect, less load on compressor, more liquid sent to cap-tube, travels faster, more lquid to evaporator,picks up more heat,more load on compressor less liquid to cap tube, on and on. I think that is pretty much the definition of modulating control however, inefficeint compared to TXV.

[docholiday]

A cap tube is a (explative) fixed metering device, unless you want to sit there and shorten and lengthen the tubes throughout the course of the day.

[Mr Bill]

Originally posted by fat eddy
I'm going to assume that everyone knows the difference between an orifice and a piston.

I don't could you please elaborate? I am here to learn like Doc.

[fat eddy]

I'm done with it, A cap tube is not a fixed metering device never has been, was never meant to be, and never will be.

[high mall drifter]

hey eddie, don't mistake a mountain top for a burro ride around the bottom of the Grand Canyon.

[fat eddy]

HIgh Mall,

Wave yur hand please, you look like yur pretty far down there buddy, wait a minute oh know thats not High Mall Drifter its Norm and the guy with four initials.

HELLOOOO down there can you heaer ear ear me down there Norm, hold on buddy I'll come and get ya I know ya took that one pretty hard I didn't mean to hurt ya though honest I didn't.

Patty will you try to keep those guys from hitting bottom while I hike down there ?

[dpatty]

so what kind of operating range would you say cap tube systems have. I have seen txv's operate over a several ton range.

could you say, take the cap tubes from a 3 ton evap and use them on anything from say 2 ton to 4 ton just as an example. if not why, I would consider an oprating range the defining charictaristic of a modulating metering device. Prove that then you may have a chance of actually winning this.

[airmechanix]

...this, is what makes me love this forum...humorous yet informative

Keep up the good work!

[fat eddy]

I never made claim that it was a good metering device or very versatile just simply stated that it is a modulating metering device and I got nothing but greif for my sincere efforts.

The cap tubes claim to fame was that it was more economical than the other devices of its day and that it nearly by itself propelled the domestication of small refrigeration systems.

[rsmith46]

Fast Eddy, you really should think about teaching seminars to enlighten other tradesmen. Somebody sure has had fun teaching you.

[dpatty]

i agree with you except for the modulating part. it is a action reaction device with known outcomes under known conditions and they do not change. that is the nature of fixed metering devices. a modulating device can change those outcomes or maintain them under other conditions

[fat eddy]

I then will assume that a TXV's reaction to an action is unknown and therefore it must truly be an uncontrollable but none the less modulating metering device, but wait a minute wait a minute here I think I remember reading somewhere that it was very well known how it would react to temperature change at the bulb wow wow wow this is great we are truly getting somewhere now if we are not very very careful we might discover something new to the field here tonight, since the reaction to an action is predictable the TXV must certainly be a fixed metering device, Nah, I'm going to go with modulating.

Give it up yur outmanned and I got to get some sleep.

Oh yeah I read that in the instructions.I remember it now, the little blue and white piece of paper with the label "read this first" on it.

[dpatty]

Lets take a poll.

Has anyone even began to think that on any level that fat eddie know what he is talking about?

I think I know what he talking about but I don't think anyone would define it as modulation much less to say that the device used is modulating.

unfortunately eddie I have to go to bed 5am comes to early in the morning to stay up debating this. I can say it has been fun.

I'll be back tomarrow

[Wild Leg]

A modulating device with NO moving parts.

Can you name another?

[Carnak]

Originally posted by dpatty
Lets take a poll.

Has anyone even began to think that on any level that fat eddie know what he is talking about?

I think I know what he talking about but I don't think anyone would define it as modulation much less to say that the device used is modulating.

unfortunately eddie I have to go to bed 5am comes to early in the morning to stay up debating this. I can say it has been fun.

I'll be back tomarrow

No I gave up on him when he told a HO to use B-vent for oil. He saw the error of his way on that one eventually.

[svtti123]

Some interesting information on cap tubes and more.



http://www.climaticcontrol.com/info/jjzgate/Infotec/Info-Tecs1-10/Infotec_8(rev1).htm Home Page[/url]


[Edited by svtti123 on 02-15-2005 at 02:03 AM]

[Carnak]

That is an interesting article svtti, it is the first thing in this thread that mentions subcooling which seems to be the key to it all.

The cap tube is still at the mercy of what leaves the condenser, a little more subcooling seems to compensate a bit for reduced head pressure.

More subcooling, less flash, more mass flow rate. I never thought of it as liquid having a higer velocity, I always thought of it as liquid having more mass.

[Carnak]

Same arguement would apply to distributer tubes after an orifice

[Wild Leg]

Quoting from http://www.climaticcontrol.com/info/jjzgate/Infotec/Info-Tecs1-10/Infotec_8(rev1).htm
"...cap tube itself cannot change its flow rate..."

[fat eddy]

It modulates, according to the load however not efficeintly. I'm done with it, I almost got booted because of this thread so I'm going to become more agreeable.I apolegize to anyone I may have offended.

[fat eddy]

Thank You,

For posting that info it is pretty much what I was saying, although I think they will still argue their mute point.

[dpatty]

I was at no time offended, to the contrary I was amused and entertained. although one of my remarks may have been, my apologies

[mo-flo]

how did you guys know i was coming?you guys have been waiting on me,ain't ya??.....got a cap tube system today,and i'm learning......would this explain why when i pressured lines i had equal pressure on both sides????i pulled vacum it held and pressured it up and thought i had leak.....................

[fat eddy]

neither the orifice or a piston have a bubble point, correct me if I am wrong.