high/low side insulation

Can anyone tell me the reason that the low pressure line of home A/C unit is insulated, and the high side line is not?? It seems to me you would minimize the affects of external heat gain/loss by insulating both lines, thus being able to fine tune the system a little better.
Thanks, Brad (AZ - very hot)
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Cost...
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efficiency( Albeit not very much)- there's no need to insulate it unless you have a situation where it runs for a distance in a very hot attic after a hefty lift or something goofy like that where you could get flash gas at the metering device.
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Back that one up..
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Exception to the rule in AZ
Here almost always using HP and so typically both line have a foam layer.
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Then there that danged clear one no iders, seemingly leaks condensate all the time
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If there is a temperature difference between ambient air and the liquid line you WILL either have greater subcooling of less. Heat transfer doesn't stop when it leaves the condenser.
Back it up? Ok, why do they say take your subcooling measurements at the outlet of the condenser coil: if it didn't make any difference take it at the reciever outlets. I know, line pressure friction loss ect, but heat transfer is also a factor, the reciver doesn't have 'line friction loss' but we try not to take our readings on the outlet of the reciever.
I've seen units not run because they GAINED temperature and LOST subcoolling and then the units capacity was short. Happens all the time in steel mills, attics etc. Happened at a Glidden paint plants computer room a few years back. So the reverse is true as well too.
The key words were "Albeit not very much-" But in a foundry it can make a difference if you don't insulate the liquid lines.
Rich
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Brad said- "Brad (AZ - very hot)"
From the perspective that Brad was in AZ -plus he even felt the need to mention the fact that it was very hot- It is reasonably obvious that he was concerned that heat on the liq line has an effect on efficiency...
Jr said "If you ""insulated"" the high side line you would probably ""lose some efficiency"" ( Albeit not very much)"
You also confirm that heat can and indeed does effect subcool etc so you too question jr's response
So within the context of Brads post Jr's quip is way off, which is why I asked him to back it up..
Cheers
Richard
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even in arizona you can still gain ambient subcooling on the liquid line . Op said nothing about an attic in the original post-- cheers Mark

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Hell, most people out there have a package unit on the roof. <G>
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If for no other technical reason, the low pressure suction line will sweat from humidity in an attic and possibly drip water on the ceiling below it. Foam insulation reduces the contact area of the suction line from the humid air. It keeps the suction line from picking up unwanted additional heat in an unconditioned space. However, now that I notice you are in AZ, you don't have to worry much about humidity.

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actually right now is the rainy season in arizona, very humid

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But he does have to worry about cooling the compressor.
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Are you HVAC person because if you are god help ous Tony

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No, I am not an hvac person. I am just trying to get some understanding of how this stuff works. I would think that you would want the liquid line to be as cool as possible when it hits the expansion valve. In the heat of the summer, the attic may be 150 degrees, which would be a bad thing if the line heats up enough. I also have a fairly long run ~60ft in the attic.
I peronally haven't seen anyone have the liquid line insulated (in AZ - residential), so I guess I have to assume that the subcooling is sufficient to prevent any flashing.
Brad
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For your installation, insulate that biatch!
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I am sorry Brad I was being wise ass If liquid line is subjected to hotter conditions then condensing temperature then yes perhaps it would help to be insulated that goes for any refrigeration system. If sub-cooler is use then sub-cooler must be located as close as possible to the TXV and liquid line should be insulated. Sub-coolers in cap tube jobs are not much beneficial unless is on refrigeration system at -20 or lower temperatures. in domestic and commercial set ups sub-cooler is use to keep suction line from freezing up or sweating and not for efficiency as what some guys believe and I am not saying that it does not help. What I am saying that OEMs have put those sub-coolers in to system to super-heat the suction line as I have stated and perhaps at same time preventing any slugging to compressor. Tony www.cas-environ.com
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