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If gravity is in your favor then don't worry about miscibility.

Thanks for reply. The parts house push oil change every time you change R22 to 407C. Reason I was wondering because sometimes you run across a customer that has refrigerant leak and wants to get by until summer to change the equipment. It just doesn't make a lot sense to do oil change if the equipment that is going to be change out soon.

Well; I guess the experiment is still ongoing as I have seen no trouble yet.

The concern is for oil return - not directly for lubrication. The 400 series refrigerants are not a solvent for mineral oil so it is not carried along with the circulating refrigerant. But most systems - most especially comfort cooling systems are under-piped. So the vapor turbulence and vapor velocity is almost always way too high. Sure this is easier to tolerate in comfort coolings - as opposed to refrigeration - because the suction pressures, and so the vapor densities, are higher than those in low temperature systems. So the pressure drop causes less compressor efficiency losses in comfort cooling applications.

But . . . . that Works For Us in terms of oil return. The high vapor velocity and turbulence in the piping serves to 'mechanically' return the mineral oil to the compressor and so all is well.

So far anyway. <g>

PHM
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Originally Posted by sammyray

I maybe wrong but didn't you post awhile back that you were experiment on R22 central air unit using 407C without oil change to see how long it will run before problem occurs. I was wondering what the results of that experiment was.

Originally Posted by sammyray

I maybe wrong but didn't you post awhile back that you were experiment on R22 central air unit using 407C without oil change to see how long it will run before problem occurs. I was wondering what the results of that experiment was.

Originally Posted by Snapperhead

Ive changed a bunch to 407c and never touched the oil ....

We did a bunch of 22 -> 407C (AC) conversions a few years ago... here are the procedures/results:
When the suction line was a definite downhill (evap coil in attic or 2nd story attic)... no oil change or additives...
When the suction line is more level: add 1/2 pt of POE to the system when changing refrigerants.
We have had ZERO failures so far...

Ive changed a bunch to 407c and never touched the oil ....

Originally Posted by Poodle Head Mikey

All design is compromise. You can't have everything.

I have used R-407A, C, and F. Although it's not technically accurate - I find it easiest to visualize / project the actions of the various 407's as though they were blends of R-410 and R-134. With A having the least 410 and F having the most 410.

R-410 is a nice refrigerant but it runs 'too hot' to work well for low temperature (high compression ratio) work. The R-134 component serves to 'cool down' the system. Of course R-134 has a much greater 'pounds pumped per hour' requirement to get equal BTU performance - so, for a given compressor, the greater the R-134 portion of the blend; the lower the BTU performance

So the 407 blends walk a fence-line between those two factors. It's nice to have the higher suction pressure / higher vapor density for the compressor efficiency but you can't burn the SOB up either. <g>

I have weighed in a 50/50 blend of R-410 and R-134 (in the field and not in a lab <g>) and found the performance to be the same as R-407C so far as I could tell. That was using an R-22 compressor with POE oil.

When R-410 first appeared my initial thought was: Here we go - a nice low temp refrigerant which will maintain great suction pressures at low temperatures. I was wrong about that. At first I was annoyed that all R-410 TXV's were for comfort cooling - but eventually I came to realize why. <g>

Most people I talk to in real life have zero interest in any of this. I know this because of their routine use of their signature-question. Which is:

"Yeah OK, so what should my pressures be?" <g>

PHM
---------

I maybe wrong but didn't you post awhile back that you were experiment on R22 central air unit using 407C without oil change to see how long it will run before problem occurs. I was wondering what the results of that experiment was.

Originally Posted by Poodle Head Mikey

All design is compromise. You can't have everything.

I have used R-407A, C, and F. Although it's not technically accurate - I find it easiest to visualize / project the actions of the various 407's as though they were blends of R-410 and R-134. With A having the least 410 and F having the most 410.

R-410 is a nice refrigerant but it runs 'too hot' to work well for low temperature (high compression ratio) work. The R-134 component serves to 'cool down' the system. Of course R-134 has a much greater 'pounds pumped per hour' requirement to get equal BTU performance - so, for a given compressor, the greater the R-134 portion of the blend; the lower the BTU performance

So the 407 blends walk a fence-line between those two factors. It's nice to have the higher suction pressure / higher vapor density for the compressor efficiency but you can't burn the SOB up either. <g>

I have weighed in a 50/50 blend of R-410 and R-134 (in the field and not in a lab <g>) and found the performance to be the same as R-407C so far as I could tell. That was using an R-22 compressor with POE oil.

When R-410 first appeared my initial thought was: Here we go - a nice low temp refrigerant which will maintain great suction pressures at low temperatures. I was wrong about that. At first I was annoyed that all R-410 TXV's were for comfort cooling - but eventually I came to realize why. <g>

Most people I talk to in real life have zero interest in any of this. I know this because of their routine use of their signature-question. Which is:

"Yeah OK, so what should my pressures be?" <g>

PHM
---------

Interesting... enjoyed the part about mixing 410 and 134...

Did you, by any chance, figure out the glide...
And even more interesting... which one would leak out first???

We have done a bunch of 22 to 407C conversions... they seem to work nicely!

All design is compromise. You can't have everything.

I have used R-407A, C, and F. Although it's not technically accurate - I find it easiest to visualize / project the actions of the various 407's as though they were blends of R-410 and R-134. With A having the least 410 and F having the most 410.

R-410 is a nice refrigerant but it runs 'too hot' to work well for low temperature (high compression ratio) work. The R-134 component serves to 'cool down' the system. Of course R-134 has a much greater 'pounds pumped per hour' requirement to get equal BTU performance - so, for a given compressor, the greater the R-134 portion of the blend; the lower the BTU performance

So the 407 blends walk a fence-line between those two factors. It's nice to have the higher suction pressure / higher vapor density for the compressor efficiency but you can't burn the SOB up either. <g>

I have weighed in a 50/50 blend of R-410 and R-134 (in the field and not in a lab <g>) and found the performance to be the same as R-407C so far as I could tell. That was using an R-22 compressor with POE oil.

When R-410 first appeared my initial thought was: Here we go - a nice low temp refrigerant which will maintain great suction pressures at low temperatures. I was wrong about that. At first I was annoyed that all R-410 TXV's were for comfort cooling - but eventually I came to realize why. <g>

Most people I talk to in real life have zero interest in any of this. I know this because of their routine use of their signature-question. Which is:

"Yeah OK, so what should my pressures be?" <g>

PHM
---------

Originally Posted by Snapperhead

I just spoke with my supply and they only stock 2 jugs 407F , and said they almost never sell it

Anyone use it ?

Hey Poodle , its been a few years , are you currently stocking both 407 A and C ?

Originally Posted by Chuck

I guess I just replied to a 7 year old post LOL

*

It happens

I guess I just replied to a 7 year old post LOL

This is interesting. I've done a few r22 to 407a conversions and the liquid injection still cycles, couldn't tell much difference, but of course I never timed it before the conversion so it very well could be less.

Originally Posted by Phase Loss

I just completed 2 stores (4 racks) from R-22 to R-407F.

Under R-22, liquid injection would cycle.

Under R-407F, liquid injection is not even needing to run.

I do

I just spoke with my supply and they only stock 2 jugs 407F , and said they almost never sell it

Anyone use it ?

Hey Poodle , its been a few years , are you currently stocking both 407 A and C ?

Didn't even know there was a 407F

Originally Posted by bunny

It's also the higher percentage of R-32 which causes the R-407F to have discharge temperatures much closer to R-22....not a good thing.

I just completed 2 stores (4 racks) from R-22 to R-407F.

Under R-22, liquid injection would cycle.

Under R-407F, liquid injection is not even needing to run.

I have heard that 407c doesn't have that great of oil return so using on a rack with an oil seperator is why it is for supermarkets. 407a has a better oil return (mixing ability). Kinda like r422d (I think) has crapy oil return and must be ran with about a 50/50 poe and alk.

Actually POE has a better tolerance for high temperatures. Mineral oil starts to decompose at 350F and POE starts to decompose at 400F.

I've attached a spreadsheet showing the chemical makeup of some of the popular R-22 replacements. It's the R-32 and R-125 (lower boiling point refrigerants) which give R-407A and R-407F more capacity than R-407C. It's also the higher percentage of R-32 which causes the R-407F to have discharge temperatures much closer to R-22....not a good thing.

We have a couple stores with 407C for medium and low temp.

If you all recall; the only reason for R-502 was that R-22 ran excessive DSH on LT applications. And this was a real problem with mineral lube oils as thermal oil breakdown would coke up the valves. Synthetic oils would have also solved the problem but Dupont makes refrigerants and not lube oils. <g>

I don't think POE oils like high temps either - although they don't coke, I do think something else comes out of them (whatever clogs up cap tubes) when they get overheated.

I wonder if there is any synthetic refrigeration oil which will both play nice with the 400 grade refrigerants And remain stable at high temps?

Any ideas?