Use of R22 compressor in R12 application?

[flintsys]

Hello,

I have a new R22 condensing unit available to me that I want to use in an R12 (R414B) system. Outside of removing any remaining R22 and resetting the pressure controls, does anyone know of any problems I may run into?

Thanks for any help.

[LRAC]

Hello,

I have a new R22 condensing unit available to me that I want to use in an R12 (R414B) system. Outside of removing any remaining R22 and resetting the pressure controls, does anyone know of any problems I may run into?

Thanks for any help.

Would imagine it will be oversized for the job and will over condense which in turn could cause big problems. Also miss match with evap duty.

Regards
LRAC

[lana]

Would imagine it will be oversized for the job and will over condense which in turn could cause big problems. Also miss match with evap duty.

Regards
LRAC

Very sorry to point this out but there is no "over condensing".
If the condenser is over sized then the condensing pressure would be normal but it can not decrease too much. The reason is the ambient or water temperature which is normal values. Assuming that the condenser is 100% efficient (not possible) then the condensing temperature would reach the ambient temperature. SO you can see there is no 'Over condensing".
If the condenser is over sized, the problem would be the refrigerant charge.
Cheers

[US Iceman]

lana,

"Over Condensing"
"Under Condensing"

I have seen these phrases used before on this site, but it is also the only place I have ever seen them used. I once asked what this meant and am still not sure.:rolleyes:

I'm still not sure of the definition. LRAC, can you help out with an explanation please?

[nh3wizard]

Im curious on this also, Ill hide and wait for an explanation

[US Iceman]

Why hide?:D

[chillin out]

"Over Condensing"

Temp at outfeed of condensor too cold.

"Under Condensing"

Temp at outfeed of condensor too warm.

Chillin:) :)

[LRAC]

Low ambient controllers or head pressure controllers When equipment is required to provide cooling in cold weather the external unit will over condense i.e. will reject too much heat. To overcome this problem it is necessary to fit a low ambient controller also known as a head pressure controller. This device slows down the condenser fan or uses other methods to prevent over condensing.Some equipment has this fitted as standard others do not.

Come on guys you've all worked on systems that use head pressure controls especially R22 systems for freezers or water chillers.

Kind regards
Lrac

[LRAC]

Peter 1 seems to use HP controls?

http://www.refrigeration-engineer.com/forums/showthread.php?t=3744

Kind regards
Lrac

[US Iceman]

Come on guys you've all worked on systems that use head pressure controls especially R22 systems for freezers or water chillers.


:D

Yeah, I've pulled a few wrenches in my time and probably have some refrigeration oil in my blood.

This forum is the only place I have heard these terms, so it must be something you guys use.

If the discharge pressure is too low, I certainly understand the need to keep the discharge pressure high enough for sufficient pressure to feed the TXV's. In this case, the "amount" of condensing does not change...only the liquid temperature does. In effect you have a much higher subcooling value for a given pressure.

If the ambient is warmer for the same discharge pressure, the only thing that changes is the amount of liquid in the condenser (assuming head pressure controls are used) and the liquid temperature will be slightly higher.

Again, the amount of condensing has not changed, only the liquid feed temperature for that discharge pressure.



"Over Condensing"

Temp at outfeed of condensor too cold.

"Under Condensing"

Temp at outfeed of condensor too warm.


I guess then according to that definition:

"condensing" = saturated liquid?

I'm not trying to start an argument, it's just this terminology is different than what we are used to hearing.:confused:

[frank]

You are quite right Iceman. It does appear to be an English term possibly bourne out of a lack of understanding of Thermodynamics.

Over condensing = Excessive sub-cooling
Under condensing = Lack of sub-cooling

To correctly identify it, any further cooling after the saturated condition is termed "sub-cooling" in the condenser.

[wambat]

You are quite right Iceman. It does appear to be an English term possibly bourne out of a lack of understanding of Thermodynamics.

Over condensing = Excessive sub-cooling
Under condensing = Lack of sub-cooling

To correctly identify it, any further cooling after the saturated condition is termed "sub-cooling" in the condenser.

HI Frank!! Long tme no talke
Therefor condening involves a change of state(latent heat) which is a constant state whereas subcooling is not a change of state only a change in liquid temperature...baby it's cold outside!:D

[US Iceman]

Welcome back wambat.:D

[wambat]

You are quite right Iceman. It does appear to be an English term possibly bourne out of a lack of understanding of Thermodynamics.

Over condensing = Excessive sub-cooling
Under condensing = Lack of sub-cooling

To correctly identify it, any further cooling after the saturated condition is termed "sub-cooling" in the condenser.

Therefor condening involves a change of state(latent heat) which is a constant state whereas subcooling is not a change of state only a change in liquid temperature...baby it's cold outside!:D

[The MG Pony]

tell me about it! it was warm for a bit here in BC then BAM chilly! Now I know where it came from! ;)

[Dan]

I have a new R22 Condensing Unit available to me that I want to use in an R12 (R414B) system. Outside of removing any remaining R22 and resetting the pressure controls, does anyone know of any problems I may run into?

The problem with converting an R12 condensing unit into an R22 compressor unit is that the motor will tend to overload. R12 requires a lot of displacement (piston, bore, stroke) compared to the horsepower of the motor. R22 requires a lot of horsepower compared to the displacement. You might need a CPR valve to keep from overloading the motor.

What compressor is this and what application are you using it in?

[lana]

Hi everybody,

USIceman explained in detail. I just add.

LARC says when ambient temp. drops ......condeser will reject too much heat.:confused:

When this happens then condensing pressure drops but this doesn't mean 'over-condensing'. The condensation occurs at lower temperature. Still this doesn't mean high sub-cooling:cool: . Heat rejection (kW) is the same as high ambient.

For better understanding think in terms of temperature not pressure.

When over charged the sub-cooling increases. WHY?
Because condensing pressure goes up. NOT because condenser cools more;) , it's the opposite. Sub cooling is the difference, like super heat.
Cheers

[Sledge]

Over condensing/undercondensing

We use that term a lot. Our winters are VERY cold, and summers are very hot. Condensers are sized for the summer, so without head pressure controls we have a head pressure troubles in the colder weather.
Although it is an incorrect term, we use the term "over condensing" as an industry term to explain low head pressure in a low ambient. Common term in the industry in Toronto.

[flintsys]

Thanks to everyone so far for the input. I'm relatively new to refrigeration systems, and the only systems I have worked on to date are those that have a condenser fan control to start or stop the fan at some given pressure. These are systems where the condenser needs to operate correctly in low ambients, and I always assumed it was a standard method.

If I'm interpreting the responses correctly, the expected outcome will be too low a pressure at the outlet of the condenser. I'm gathering this assumes the condenser fan runs in sync with the compressor.

If you were to regulate and restrict the condenser capacity (variable speed fan) would this counteract the expected outcome?

Thanks again for any additional input.

[flintsys]

I missed some responses before my last post...

The compressor I have is a 1 horsepower Copeland hermetic. I would be using it to replace a 1 horsepower semi-hermetic on a milk cooling tank. The condensing unit will be indoors, and won't see extreme ambients, but it will see some wide swings.

From Dans post (please correct me if I'm wrong) I'm figuring an R12 compressor will have a lower compression ratio than an R22 unit? With R12 in an R22 compressor this would mean higher discharge pressure, hence the need for the CPR valve?

From here it seems intuitive (A bad word in refrigeration I know) that this would result in too high a condenser outlet pressure... This seems to conflict the original reply from LRAC. I know I'm missing something in understanding this. I'll admit my understanding of the thermodynamics is pretty weak.

Thanks again.

[Dan]

Ok. Let's take your example. A typical Copeland compressor 1 hp for R12 duty is a KAK-0100. It has 2 cylinders, a bore of 1.69 and a stroke of .94, with cubic foot per hour displacement (CFH) of 4.20. It's capacity is 7,250 btu/hr at 20 deg F evaporating and 120 deg f condensing.

A typical Copeland hermetic compressor 1 hp for R22 duty has 1 cylinder, a bore of 1.5 and a stroke of .75 for a CFH of 1.33. Its capacity is 6,170 btu/hr at the same conditions with R22. This is less than a third of the pumping ability your semi-hermetic compressor. So if you do not change the refrigerant to R22, and the refrigerant specific components such as the TEV, you will not come close to cooling compared to the semi-hermetic compressor.

Does this make sense, stated this way?

[US Iceman]

Dan provides a good explanation on a simple but often overlooked principle. Horsepower or input kW should not be used to compare compressor capacity.

For the same reason 1 Ton (or 1 kW of cooling) at one temperature is not the same capacity at another temperature as far as the compressor is concerned.

Compounding this is the proposed change in refrigerants.

Each refrigerant will require a specific mass and volume flow to produce a specific cooling effect. The volume volume flow is particularly important when comparing compressor capacity.

If one compressor will pump "x" cubic feet (or meters) per minute that is it's useful displacement. If another compressor has "x" plus or "x" minus displacement the system responds by having either a lower suction pressure or higher suction pressure (respective to the "x" plus or "x" minus). This is what Dan was saying.

In other words, if a 1 HP compressor designed for R-12 is replaced by a 1 HP compressor designed for R-22 you will be sorely disappointed in the outcome.

The rule to remember is...Never compare motor size for compressor capacity. This does not work for refrigeration or comparison to different refrigerants.

[wambat]

Quote: "In other words, if a 1 HP Compressor designed for R-12 is replaced by a 1 HP Compressor designed for R-22 you will be sorely disappointed in the outcome."

Ice man is correct the difference in about 60% less volumetric displacement

[wambat]

Quote: "In other words, if a 1 HP Compressor designed for R-12 is replaced by a 1 HP Compressor designed for R-22 you will be sorely disappointed in the outcome."

Ice man is correct the difference is about 60% less volumetric displacement

[setrad7791]

Hi there! In response to your reply their is an overcondensing problem... You are assuming that the ambient temp is at an acceptable levels continously... what about at night where the temperature drops to 10 degress? Low head pressure equals low suction pressure... equals PROBLEMS. pressure control tripping/tx valve fluctuation/unstable superheat oil return problems.... And call outs at night which are no fun at all!

[flintsys]

Ah Hah! I see where I was missing the point...

I was looking at horsepower as a direct correlation to cooling capacity, not pumping capacity. What I was overlooking was that different refrigerants have different heat capacity per unit mass... I was thinking as if this was the same for R12 and R22, just at different pressures. Remakably basic item to overlook, great lesson learned.

Thanks to everyone for the input, I've learned a lot from this.

Regards,
Ryan

[Air duster]

Dan’s general point is correct....... but....Something doesn’t look quite right with those figures............ (see below)


Ok. Let's take your example. A typical Copeland compressor 1 hp for R12 duty is a KAK-0100. It has 2 cylinders, a bore of 1.69 and a stroke of .94,

And what is the operating RPM of the compressor? What type of duty, Is it for low temp, med temp, or high temp?


with cubic foot per hour displacement (CFH) of 4.20. It's capacity is 7,250 btu/hr at 20 deg F evaporating and 120 deg f condensing.


Ah..... that isn’t right.... (pulls out big book) The latent heat of vaporization of R12 at 20F is 66.52 BTU per pound. Total circulated refrigerant for 7250BTU/hr is about 109 pound per hour. Density of vapor is 1.1cubic foot per pound at 20F evaporator temp(21PSIG). Total cubic foot per hour is about 120 CFH. Or about 2 CFM (cubic foot per minute) for the suction side. Density of vapor at 120F(157.65PSIG) is 0.23 cubic foot per pound. Total cubic foot per hour is about 25CFH or about 0.42CFM on the discharge side.


A typical Copeland hermetic compressor 1 hp for R22 duty has 1 cylinder, a bore of 1.5 and a stroke of .75

Again. what RPM, and what type of duty?


for a CFH of 1.33. Its capacity is 6,170 btu/hr at the same conditions with R22.

(cut and past from above with R22 figures)
The latent heat of vaporization of R22 at 20F is 90.344 BTU per pound. Total circulated refrigerant for 6,170BTU/hr is about 68.3 pound per hour. Density of vapor is 0.9343 cubic foot per pound at 20F evaporator temp(43PSIG). Total cubic foot per hour is about 64 CFH. Or about 1 CFM (cubic foot per minute) for the suction side. Density of vapor at 120F(262.6PSIG) is 0.19 cubic foot per pound. Total cubic foot per hour is about 12.98CFH or about 0.216CFM on the discharge side.



This is less than a third of the pumping ability your semi-hermetic compressor.


The CFM pumping ability will depend on the designed application. Low temp, med temp, high temp.


So if you do not change the refrigerant to R22, and the refrigerant specific components such as the TEV, you will not come close to cooling compared to the semi-hermetic compressor.


Lets look at some figures. A 10,000BTU R22 compressor pulling a 20F evaporator. From above figures. Circulated refrigerant is around 110 pound per hour. Or around 103.416CFH / 1.7236CFM suction side.

You take that exact same compressor and put R12 in it. 103.416CFH. 94 pounds per hour at 1.1 cubic foot per pound. That is 6254BTU per hour. Or a little more than 62% of R22 capacity.

Compression ratios are about the same so head space shouldn’t affect the suction CFM levels any from the switch from R22 to R12.

A R22 compressor for the exact same application and capacity has a displacement value of about 62% of it’s R12 counterpart. That figure closely matches the stated figure in my other books.

For switching a complete system from R22 to R12 (or a R12 system running at reduced capacity with a R22 compressor) the delta T of the evaporator, and the condenser will be less with a reduced capacity. (They will be closer to the temp of the medium that it is cooling, or the medium that is cooling it.) So there will be a lower temperature separation that it has to move heat across. Lower compression ratio, and higher suction pressure. That will increase capacity a bit. So, real world difference is probably around 66% (or more if the evaporator or condenser was under sized) of original capacity. Or a capacity loss of about 33%. That is the most common figure that I have seen bantered about.

[Dan]

Ah..... that isn’t right.... (pulls out big book) The latent heat of vaporization of R12 at 20F is 66.52 BTU per pound. Total circulated refrigerant for 7250BTU/hr is about 109 pound per hour. Density of vapor is 1.1cubic foot per pound at 20F evaporator temp(21PSIG). Total cubic foot per hour is about 120 CFH. Or about 2 CFM (cubic foot per minute) for the suction side. Density of vapor at 120F(157.65PSIG) is 0.23 cubic foot per pound. Total cubic foot per hour is about 25CFH or about 0.42CFM on the discharge side.

I just took the data from Copeland data sheets, hopefully attached for your perusal

[US Iceman]

There is another part of this I'll offer for discussion. Since Dan used the rating sheets I think his info. is OK.



The latent heat of vaporization of R12 at 20F is 66.52 BTU per pound.


That's true for a latent heat value for that refrigerant at that temperature, BUT...This is not what you use to calculate the cooling duty or the mass or volume flow.

You have to take into account the liquid feed temperature also.

If the liquid temperature is 100°F (37.7°C), the the mass flow is derived by 200 btu/min-Ton divided by(hg-hf), where,

hg=vapor enthalpy @ evaporating temp. = 79.385 Btu/lb
hf = liquid enthalpy @ liquid feed temp. = 31.1 Btu/lb

So, 200/(79.385-31.1) = 4.1421 lbs/minute per Ton
Or, 4.1421 x (79.385-31.1) = 200 Btu/min-Ton

(79.385-31.1) = 48.285 Btu/lb which is a lot lower than just using the latent heat value (66.522 Btu/lb).

As a result the volume flow requirements will increase because the mass flow will be about 30% greater.

You were on the right path but took a wrong turn.:o

[Air duster]

If the liquid temperature is 100°F (37.7°C), the the mass flow is derived by 200 btu/min-Ton divided by(hg-hf), where,

hg=vapor enthalpy @ evaporating temp. = 79.385 Btu/lb
hf = liquid enthalpy @ liquid feed temp. = 31.1 Btu/lb

So, 200/(79.385-31.1) = 4.1421 lbs/minute per Ton
Or, 4.1421 x (79.385-31.1) = 200 Btu/min-Ton

(79.385-31.1) = 48.285 Btu/lb which is a lot lower than just using the latent heat value (66.522 Btu/lb).

ooops........ a little oversight indeed... Forgot that the liquid temp is not 20F when it enters the expansion device.


I just took the data from Copeland data sheets, hopefully attached for your perusal
I am currently scratching my head over them.....
“CFH”............... :confused: :confused: :confused: :confused:

[US Iceman]

CFH is simply cubic feet per hour. Since the displacement is so small, the term of CFH is used to have a relatively decent number.

1.5 CFH is easier to say than 0.025 CFM.

In some SI units you will see these small displacements listed as cubic meters per second for the same reason.

[Air duster]

CFH is simply cubic feet per hour. Since the displacement is so small, the term of CFH is used to have a relatively decent number.

1.5 CFH is easier to say than 0.025 CFM.

I know it stands for cubic foot per hour....... But...........

There figure they have in the box makes no sense..........

It is orders of magnitude off from what I would expect to see listed in the CFH box.

Like the copeland ZBD30KCE. It has a displacement of 498 CFH. At that CFH it has a BTU capacity of 30,500 BTU with R404A at a 20F/120F split. At 7000BTU you would be looking at around 114 CFH.

The 1.33 CFH and 4.2 CFH figures for R22 and R12 just don’t compute in my mind.:o

At this point, I just right it off as a typo, unless proven otherwise. :(

[Tocoldtohold]

I was being a noob and im stupid!!

[Dan]

I was being a noob and im stupid!!

Don't be harsh on yourself. You are going through the same thoughts I had many years ago. Chances are that you are ahead of me in your thinking because you are smart enough to ask the "dumb" question. Look at all the stir you have caused!:)


The 1.33 CFH and 4.2 CFH figures for R22 and R12 just don’t compute in my mind.

At this point, I just right it off as a typo, unless proven otherwise.

Okay, let's try a 1/2 hp comparison. See if the pattern holds up.

[Dan]

Hmmm. Here are the pages downloaded from the Emerson site. Good eye, air duster.

I was using an old copy of Compass.

[US Iceman]

Dan,

I did not look over this very closely but it appears the old datsheets did have a typo. The CFH values were actually CFM.

[Dan]

Dan,

I did not look over this very closely but it appears the old datsheets did have a typo. The CFH values were actually CFM.

I am glad Air Duster stuck to his guns. I really appreciate his courtesy and stubbornness. I enjoy standing corrected.

Even cubic feet per minute was hit and miss from one compressor to another. My general point was solid but the data was whacked and Air Duster wouldn't let it slide.

Looking forward to more posts by Air Duster. :)

[Air duster]

By golly, I think you are right!!!

All right......... let me re-chomp the figure to see if I can make the ends meet......

As US iceman pointed out, around 48 BTU pound. At 7250BTU that would be 151 pounds per hour.

Ow...... look, the R12 compressor data sheet has mass flow at 150 for 20/120 split. so the mass flow units must be “pounds per hour”

All right.... now R22. From 100F liquid to 20F gas is..... 106.4 - 39.5 = 67 BTu per pound. at 6170 BTU that is 92 pounds per hour.

And look at the data sheet for the R22 compressor.......... Yep....... mass flow rate for 20/120 split is 90!

Everything is connecting on that point...... Now lets go to vapor flow rates.

Back to R12. At 150 pounds per hour (their spec). Vapor density is 1.1cubic foot per pound at 21PSIG. That is 165 CFH “cubic foot per hour“. That is 2.75 CFM...... Which doesn’t match their displacement figure if it is actually in CFM!!!!!!! They quote “4.2”.

Lets look at R22. At 90 pounds per hour (their spec). Vapor density is 0.93cubic foot per pound at 43PSIG. That is 83.7CFH. or about 1.4 CFM. That would closely match the figure they have in the “CFH” box if it is actually A CFM figure. They quote “1.33”

Is there still something I am missing on the R12 calculation that is causing it not to match on the CFM figure???? or is the figure they quoted just totally wrong?

According to my figures at the 20/120 temp split. The R12 system is running at 2636BTU per CFM. The R22 system is running at 4407 BTU per CFM. So the R12 capacity per CFM in relation to R22 capacity per CFM is at 60%. That is, A R12 system has 60 percent of the capacity of an R22 system with the same compressor. Which is still close to the figures I have heard. It’s still close to the figure I quoted the first time with messed up calculations.

Besides that one discrepancy with the R12 compressor CFM rating on the PDF, is there anything I am missing here?

[Air duster]

I have checked my other books, and they agree. R12 vapor is 1.1 cubic foot per pound at 21PSIG.

All right. 150 pounds of R12 vapor will fill a volume of 165 cubic feet at 21PSIG.

If you move 165 cubic feet in an hour you have a flow rate of 165 CFH

If you move 165 cubic foot in an hour, then you must move 2.75 cubic foot every minute.

But they list 4.2

On the other R12 PDF’s They list 71 and 72 pounds per hour.

At 1.1 cubic foot per pound that is, 78.1 and 79.2 cubic foot respectively.

To move that many cubic foot in an hour, you must move 1.3 and 1.32 CFM respectively.

They list 123.4 CFH (2.05CFM) and 2.03CFM respectively.

They say you have to move 123.4 cubic foot per hour to move 71 pounds of R12 per hour which has a volume of 1.1 cubic foot per pound.

Please tell me what I am missing here? :(

If i keep scratching my head this hard, I won’t have any hair left!!!!! :eek:

[Dan]

Please tell me what I am missing here?

I always thought that the CFH was a direct result of RPM and bore and stroke. Is it possible that we have some 4 pole motors and some 6 pole motors? The inconsistancy has me baffled as well. Motor slippage? Clearance considerations?

I always relied on the CD "Compass" because it showed this sort of data. Cpcalc does not. The website has changed so many that I only reluctantly go there for data. In this case, I am glad I did. It is obviously time to chuck the Compass program. :(

[US Iceman]

I thought all of the motors were 4 pole, so on 60 Hertz that would be a nominal speed of 1800 RPM. Motor slip, efficiency and other factors may reduce this down to approximately 1750 RPM as an average rotational speed.

Now if I remember correctly, the displacement listed is that of the compressor, NOT the CFM or CFH of the vapor volume flow. This is normally considered the ACFM or ACFH.

What you will find is the ACFM X the VE = CFM.

ACFM = Actual Cubic Feet per Minute
VE = Volumetric Efficiency of the compressor at a specific compression ratio. The VE changes for any compression ratio and refrigerant, in a practical sense.

Since we are dealing with the actual vapor volume we have to take that into account also.

In order to understand compressor ratings you have to see how the ratings are developed. All of the Copeland compressors are usually rated on a 65°F return gas temperature.

This temperature fixes the gas density (and volume) at the stated operating suction pressures. For any given suction pressure at 65°F gas temperature you can find the actual suction superheat at that condition.

This superheat increases the gas volume and decreases the gas density. In effect, the compressor is still pumping the ACFM, but the mass flow decreases because the gas density has decreased.

You also have to check if any subcooling is provided in the ratings.

In closing, you HAVE to verify the actual rating conditions of the compressor. You cannot compare saturated refrigerant properties to a compression cycle if the rating basis includes superheat and subcooling.

[US Iceman]

I thought I might add some more to this...

ACFM / rho_gas X (hg-hf) = capacity

ACFM / rho_gas = mass flow

rho_gas is the gas density at the specific operating condition.

ACFM and (hg-hf) were covered earlier.

[Air duster]

Thanks for the info! :)

[Air duster]

Hold it here..........
My mind keeps saying something is not right.......

I got it......

We keep talking about the mechanical CFM of the compressor, the volumetric efficiency and how that affects the actual CFM flow.

All that is irrelevant.

I was trying to do calculations based on the premise that those mattered to the calculation. The premise is in error.

What makes it an error is the fact that given a set of condensing temps and evaporating temps. R12 and R22 have roughly the same compression ratio. Be it from 20F to 120F or -10F to 50F. It doesn’t make a difference. The pressure shift that R22 will see across 20F to 120F will produce the same compression ratio as R12 when you take the pressure shift from 20F to 120F.

So volumetric efficiency will affect R12 and R22 the exact same amount.

When you take into account the effect of super heating of the suction gas on vapor density. It will affect both refrigerant about the same.

So the mechanical 1 to 1 compression ratio CFM rating is irrelevant. And volumetric efficiency is irrelevant. How they come up with the CFH...... I mean CFM figure....... or what ever the he!! the figure is on the copeland data sheets.... is irrelevant. If it is not the actual CFM at the intended operating condition then forget about it!

The only thing that counts is the actual CFM the compressor produces under the intended temperature shift.

The CFM that a compressor produces with R22 under a temperature shift will be almost the exact same CFM it will produce with R12. And vice versa.

The only difference is the cooling capacity per pound the refrigerant is producing. Which for R12 is a little bit more than 60 percent of the R22 capacity.

The only difference the compressor feels is the lower pressure shift of the R12 for the same temperature shift. That lower pressure shift causes a lower level of load on the compressor motor. That lower load is also about 60% of the R22 motor load. (60% percent of the pressure shift at same compression ratio).

Volumetric efficiency may come into effect for other refrigerants besides R12 because some of them have a compression ratio that is considerably different from R22. For the same temp shift. But it doesn’t count for R12. (And by some extrapolation, R134A)

Everything makes sense again!!! It was bugging the heck out of me.:D

[PoodleHeadMikey]

Weirdly enough; I want to do something almost like that right now.

I have a 1 HP TPCo R-12 medium-temp compressor which is stuck.

I also have an almost-new 2 HP Copeland R-404 low temp condensing unit sitting here.

R-404 acts just about like R-22 - so far as I know. Am I right? <g>

Now then - what will happen if I replace the 1 HP R-12 condensing unit with the 2 HP R-404 condensing unit AND charge the system with R-414 ? (an R-12 drop-in replacement)

After reading the posts above I am thinking that while the R-404 compressor will pump 60% less refrigerant per ton - it will be roughly double the capacity to start with. Making it only slightly oversized for the system's capacity requirements.

Opinions?

PHM
---------





. . . . Ice man is correct the difference is about 60% less volumetric displacement

[winks]

hi every one,
im a new member, and i need HEAT LOAD CALCULATION softwear or program