When a blend has different letters after the same number (A and C), it means they have different percentages of the same refrigerants used in the blends. They both have the same refrigerants in their blends, just different ratios.
My guess is 407A is blended to work better in low temp, whereas 407C is more toward medium temp, because of differences in pressure/temp relations.
I'm not a chemist or know exactly what it is but i think that 407a has something added to the blend to help with lowering the discharge temperatures on higher compression ration(MT/LT refrigeration, what ever it is i believe lowers the efficiency of the refrigerant a bit and also raises the GWP ratio of the gas,
407c is a bit more efficient and has lower GWP but only is good for HT refrigeration, but no good for MT/LT due to discharge temps
i could be completely wrong but thats what i'm going with for now hahaha
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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?
PHM
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When faced with the choice between changing one's mind, and proving that there is no need to do so, most tend to get busy on the proof.
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.
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.
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.
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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
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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 ?
PHM
--------
When faced with the choice between changing one's mind, and proving that there is no need to do so, most tend to get busy on the proof.
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
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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!
GA-HVAC-Tech
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Originally Posted by bunny
