Refrigerant Condensors

sorry there has been a mistake so I repeat my question,,

What will be the effect of fitting a 2 TR condenser to a 1.5 RT domestic split air conditioner, presuming all other system components are in good condition?

Is there any way to check a compressor independently for performance before fitting in the system??

How does the quality of a refrigerant affect the performance of a domestic split air conditioner and what is the way to check refrigerant quality??

usually quality of a refrigerant is judged here by its price and seller...

Domestic split conditioners are rated for 1.5 TR but after some time their capacity drops,,,Given that condenser , evaporator are in good condition can I fit a 2 TR used compressor to my old 1.5 TR air conditioner??

The internal volume of the 2tr condenser will be larger, the condensing pressure will be lower and as the "heat exchange" surface area will be larger the condensing temperature will be lower. the difference between ambient and condensing temperature will decrease leading to lower heat transfer.

If you feel that your unit is not cooling enough or that it has reduced, you can try cleaning the condenser with a "car high pressure washer" ( take care not to damage the fins ). The surface of the fins once cleaned will lead to better heat transfer and better efficiency.

Don't unbalance the system.

that does make sense but wouldn't the larger condenser reach an optimum pressure limit after a short while and correspond to condensing temperature? I think the purpose of installing liquid receivers in the system too is to store condensed vapor into them for release at low evaporating pressure/temp to the evaporator through expansion valves . Then why would the bigger size of a condenser wount do that??

still I am not able to get answer to my question viz how to check a hermetically sealed rotary compressor, old or even a new one, for fitness without installing it in the system?? Of course this would be without knowing manufacturers guidance.

The volume of gas pumped by the compressor is the volume per stroke x rpm. or in case of rotary compressors it is a function of the rpm. However the "mass" of gas is dependent on the temperature and pressure.

Normally the amount of gas charged is based on the amount of liquid that will fill the evaporator at the desired temperature, having a larger condenser will only mean a lower condensing pressure.

Receivers are used to prevent ingress of liquid refrigerant into the compressor ( in case of a sudden reduction of heat load or flooding of evaporator.

Most split units have a capillary as a throttling device and the above holds true. In case of expansion valves the receiver will hold the excess liquid refrigerant.

Q? Why are you considering a larger condenser? If you feel that the cooling capacity has gone down, suggest you check for gas leakage. Look for oil residue - that's where the leak if any is.

If you just throw something together with miscellaneous parts, and questionable refrigerant, there is no guarantee of performance spec....These systems are engineered from start to finish with components designed for the purpose needed....Having said that, generally speaking increasing the condenser size 1/2 ton will not hurt performance and oversizing the compressor may throw the pressures off enough to make the system problematic, or maybe just lose some efficiency....

thanks but could you please let me know the 'rule' which governs 'misc parts' co relationship?

I do understand that fitting a larger capacity compressor will handle gas volume too quickly and create cooling problem but I agree with you that fitting a bit larger condenser will not matter.

anons

Addressing your question "what is the way to check refrigerant quality?"

I don't understand why if you are using a known refrigerant, that you are concerned with it's "quality". If it's e.g. R410A, then why would your vendor deliver something that is not pure, and mixed with unknown gases.

If you know what is in your refrigerant drum, and there is enough quantity to have a saturated vapor/liquid state, and if you can let it stabilize in an area that has a constant temperature, measuring the pressure in the drum, and comparing this to the pressure vs temperature chart for that refrigerant, will validate it is correct if they correlate.

It's possible you may need to check this at different temperatures, as this will prove a known refrigerant in the drum.

R22 is sold here from usd5 to usd 25 per kg .If the gas was the same then why this price difference? The pricey gas works better,,,,,hence my question.

New R22 has been banned for use since 2010, only reclaimed R22 is allowed. This is true in the EU and US markets. So unless your country is not part of this agreement, you are getting R22 as reclaimed only. The cheap stuff is probably mixed with R12, R134A, R410A, R502, and any other condensible recovered refrigerant. There are R22 replacements that would be a better route to go if you want predictable system operation. But R410A has a higher working pressure, and this may lead to system leaks if your compressor and condenser is not capable of this.

Thanks . I take your point..

and have voted your answer as a

good answer!!

Now, I want to ask how does fitting an oversized condenser affect the performance of a refrigerating system? Conversely how does fitting an over sized evaporator affect the refrigerating system? I know in the latter case flash gases will reduce the cooling effect.

In the former case I imagine vapor will get turned into liquid more quickly ...but I am not sure how will it improve 'cooling effect'?

There is NO restriction on using arctons in my country.....

It is not easy to check the quality of the refrigerant and I have no alternative but to buy by the price of it as only the dealer knows what the hell he is selling!

gas charging is not a difficult job ...either I will hire a guy..our professionals hold NO qualification certificate...and can't be trusted...so will have to buy refrigerant myself and tell the bugger to evacuate the system and recharge it with new gas....

I hope that way I might be able to get better cooling from my AC i return for the electricity it consumes..

Deleted as SE already said this.

are you referring to Mollier's chart?

"fitting a (did you mean 2? here) TR condenser to a 1.5 RT domestic split air conditioner?"

"can I fit a 2 TR used compressor to my old 1.5 TR air conditioner??"

Are you fitting a condenser or a compressor to your unit?

Have you considered hiring a pro?

lyn, it's a used compressor n i guess used compressor provide lesser efficiency which may be near or equal to a new one of lower TR

No....that is not true...a 24,000 btu compressor will remain so until it fails.....The actual BTU's of a rated system may vary considerably from unit to unit....to be accurate you need to check the actual btu rating by model number of the compressor, and I would also get a new run capacitor of the proper size that would be recommended by the compressor manufacturer.....If you are buying used refrigerant, you need to be concerned with contamination, but a good filter drier should help...you should charge the unit through a separate filter drier and add another to the system....you can check the ph of the refrigerant with a test kit, if it tests acidic, you need to add a neutralizer....are these sealed or semi-hermetic compressors? Do you have a thermostatically controlled x-valve, or other restriction device? By increasing the size of the evaporator coil you increase the load, and the amount of refrigerant required, and the need for more pumping power from the compressor....I don't recommend this....with a larger condenser coil, more refrigerant will be required, but the velocity of flow reduced, this might result in a slightly lower load on the compressor,,,,but it depends on the condition of the coil, and other factors....

thanks,,,,

my compressors are sealed hermetic rotary type,,,

yes, capacitor needs to be changed bt that's no problem

A little perplexing is the fact that a used or old compressor would always have the same efficiency is not understandable, What about the wear and tear it would have undergone during its previous use>?

I take you point on increased load on evaporator but it again depends upon the capillary tube feeding it with liquid refrigerant. Even if it doesn't increase the load on evaporator the use of a thinner capillary Or a smaller expansion valve will increase flash gases in the evaporative thereby reducing its cooling effect,.

I guess that the refrigerant 'charged' by the pro's is used one,,,,they lie and sell it as fresh one,..'

here is a link showing the AC

https://www.google.com.pk/search?q=split+room+air+conditioner%2Bimages&client=firefox-a&hs=joO&rls=org.mozilla:en-US:official&channel=fflb&tbm=isch&tbo=u&source=univ&sa=X&ei=CpveU4ymCMSb0QXVvoHQBw&ved=0CB4QsAQ&biw=1958&bih=942&dpr=0.7

hi...the above problem is not mine but a friend's working on my puter!!

Well do older motors lose hp? No they don't...The txvalve or capillaries are sized to the evaporator coil, which is sized to the compressor....In other words you need matching components, an 18k compressor needs and 18k evaporator coil which needs an 18k restriction device, any alteration will cut performance, raise cost of operation, and shorten the life of the equipment.....The coils can lose effectiveness over time through corrosion and dirt and/or debris accumulation, damage to fins or algae growth...so the coils need to be clean, the fan blades need to be clean and straight and properly located and situated.....the motors need new capacitors occasionally, but do not lose speed over time.....the bearings wear out, or the windings short out....A compressor relies on the return refrigerant to keep it at operating temperature...if you alter this, the compressor will overheat....I would switch to some other reliable source for virgin gas...

http://www2.dupont.com/ISCEON/en_US/products/ISCEON_MO99.html#.U97kz_ldWSo

http:/https://www.youtube.com/watch?v=nl9geEG-pUs

www.coolingpost.com/world-news/pakistan-plugs-hcfc-loophole/

thanks a lot... I get your point ..

but doesn't a mechanical device such as an engine etc lose its efficiency with time??

I think it does if some of its internal moving elements such as rings and piston etc get worn out? This may not happen with electrical devices such as motors..though

anyway, thanks again and one vote for good answer,...catch the gift!!

..."doesn't a mechanical device such as an engine etc lose its efficiency with time??"

Generally speaking for an engine this may be true, but it's due to lack of maintenance...Properly maintained it retains it's efficiency....check your gas mileage....if it starts to go down, you have a problem....A compressor, on the other hand, is a sealed unit, electric motor driven pump constantly lubricated in a bath of oil...like an automatic transmission in a car, properly maintained will last indefinitely...almost all compressor failures are from electrical stress from unusual load...and/or contamination of the refrigerant which causes an acidic ph that in turn causes loss of motor winding integrity, resulting in subsequent short circuit....

you are right but no machine always operates in 'ideal conditions'. Same holds true for AC compressors. In a country like Pakistan you are never sure of what you get for your money..it could be adulterated oil, gas and even bad workmanship. For example a bad pro is liable to leave kinks in the suction line without you knowing it until your compressor goes bust! This has happened to me,,,often..and that's why I asked how to check the quality of refrigerant? Will try the acid test though...

Is there any way to check a second hand AC compressor, hermetic, rotary type , for efficiency without it being fitted to the system?? Usually it is done by running compressor for pumping air and noting the discharge pressure. However, some clever pro do check the 'back'' for fitness and if the compressor valves are leaky they will throw back air to the suction inlet. I have not tried this method..have you?

The compressor, if used and being repurposed, should be sealed when removed, and remain sealed until it's installed....There's no such thing as a static valve test for a compressor, it's needs to be tested under load....The only way I know to test the valves in a rotary compressor, is to run it under full load conditions and check the output and amp draw....If you know how to measure true btu output of the unit....if the valves are bad you won't be able to get proper pressure readings....low head, high suction, low amp draw, overheating of compressor....these would be signs of bad valves, or weak valves....You might also install a sight glass in the liquid line....this should be solid, no bubbles, when unit is under full load.....

http://www.profengineering.com/node/137

unfortunately the second hand compressors here and even the new ones are sold without warranty...

old compressors are seldom closed at their inlet and outlet....and that is not good too as moisture gets in them

So what I have to do is to take a chance or bind the seller to his word of honor so that if the compressor doesn't work on load it will be returned or replaced ...in a couple of days. However, this is not so simple because often it takes time to fit and if it doesn't work the refrigerant and the whole exercise of refurbishing the AC goes waste.

Thus the only way for a safer and cheaper way to buy a second hand compressor is to find some , yes some way to check it for performance in static...ie on hand and without installing in a system.

I think with science having got so much advanced there might be some way to solve this problem...wonder if some friend here has worked on it.

the idea of fixing a sight glass in the liquid line is good,....and is already in vogue with some brands..nowadays refrigerators are coming in with built in 'inverters' to control power fluctuations from 130 V to 270 V...and that is a good development.

I just fixed my AC after fitting a second hand compressor to it...on seller's word for being good.. The first time he gave me one didn't work so i had to dismantle it and exchange with another one, which is working quite well...

Because the outer condensing unit of a domestic AC is hung outside the house in a casing,,,it becomes more difficult to check the feel of temp between the suction and liquid lines....as emanating from the compressor...however, i will try to check from their branches leading indoor...

By the rule of thumb the suction line should be cooler than the liquid line,...

I cannot check compressor to see if it is hot or tepid because it is shut in a casing...and overhung...

I would need a tong tester to check the amperes...yes. Can anybody lend me one or do I buy a new one for myself?:)

thanks again, SE!

However, I still feel it isn't working as well as I feel....maybe bad refrigerant , choked drier filter or perhaps the compressor itself? I serviced other components myself and they are in perfect condition,,,so problem if any lies with the former elements i doubted...but it is okay for our summers.

One day I am going to buy me refrigerant on my own,,,,,will search for a good supplier.....evacuate the system and recharge it anew..If even then the AC didn't give good performance I will have to throw it out!

Not being an engineer,,life seems so hard strugling to fix a poor AC!!

It is the struggling of life that makes us stronger, and smarter.....a compressor that has been open to the air for any length of time, will require an oil change, 24hr evacuation, and new filter driers, suction and liquid line...even then you'll be lucky if it lasts past 6 mos.....when fully charged the suction line should be cold, and the liquid line warm....another way to check if the unit is carrying a good load is to check the condensate flow....the unit when first started and running for say 10 minutes, should have a rapid steady dripping of condensate, possibly even a constant ribbon of flow....another way is to measure the temperature gain across the condenser coil, it should be about a 30ºF temperature rise across the coil....

Thanks, there is least to disagree with you:)