Only insulate the cold copper - right?


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Old 02-02-19, 03:52 PM
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Only insulate the cold copper - right?

The A/C installer ran both copper lines inside the insulation. I questioned the wisdom of putting the hot line in there but he assured me that's how it's supposed to be done.

Now I'm replacing the insulation because its deteriorated.

I only have to insulate the cold line - Right?
 
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Old 02-02-19, 04:42 PM
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Roatan, your installer is correct. By running the hot and cold lines side by side, your equipment gets the thermo benefit of increased subcooling and superheat by the transfer of heat between the two lines. Although it is not always required by the manufacturer, joined lines are a superior method of installation. Technically, the hot line does not need insulation, but the cold line always needs insulation to prevent condensation inside your home.
 
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Old 02-02-19, 05:43 PM
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It depends on what type of air conditioner you have.
A conventional split system would have the suction line which is the one that gets cold insulated and the liquid line is not normally insulated.
A mini split unit requires the suction and liquid line to be separate with both lines insulated.
 
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Old 02-04-19, 06:14 AM
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@airmark, @GregH

Thank you for the reply. I read through the installation manual for the unit, but it didn't explicitly note how to handle the insulation. There was a drawing of the outside unit with plumbing leading to it that had both lines within the insulation.
Honestly, that didn't make sense to me. Adding the hot to the cold produces warm, which isn't what I'm after. I don't pretend to understand how A/C works, so will take your and the manuals advice. I'll get new Armaflex insulation that can encapsulate both lines.

Thank You
 
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Old 02-04-19, 06:38 AM
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I'm far from being a pro on this subject but the explanations so far fail to convince me that both lines should be side by side inside some insulation. Maybe there are reasons that each should be insulated but seems to me they should be isolated from each other. Clarification needed.

Bud
 
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Old 02-06-19, 05:30 PM
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Smile All configurations are acceptable.

Hi Bud9051, It is intuitive that a hot and cold line should be separated, so it begs the question of why join them.
In a perfect A/C system, the hot line will always contain liquid refrigerant and the cold line will always contain cold vapor. In that case, there is never a need to join the hot and cold line together to exchange heat.
However, in practice, this is just not always the case. A hot liquid might contain undesirable hot 'vapor/gas' when it is 100 degrees outside or the blower filter is clogged, or other causes. A cold line might contain undesirable cold 'liquid' if it is overcharged or ambient's are below 60 degrees outside, or other causes. These two undesirable refrigerant states (liquid/vapor) are harmful to both the compressor and the capacity to cool the building.
By joining the two lines together, these undesirable states are either minimized or eliminated, which tends to bring the system back to the design equilibrium. Furthermore, there is no downside to this method when the two lines are 'always' within design states (liquid/vapor). The temperatures of the line contents may be affected by this heat sink affect, but the liquid/vapor 'state' is not. And it critical to the system design that there is liquid in the hot line and vapor in the cold line.
Given that there are millions of installers, you can expect different installation results. Joining lines is superior but not required, and may even be costly. For example cold lines are often factory made with the insulation already wrapped. There are other valid reasons to insulate or not to insulate, that are not critical to the installation. However, the most essential requirement is that the indoor cold line must be insulated to prevent condensation, which, oddly, has nothing to do with the critical liquid/vapor state of the line. It is easier to not group the two actions into one. There are millions of units with and without joins, with and without insulation here or there. Do not worry that something might be wrong. All configurations are acceptable. If you home is cool in 90 degree whether then you are in good hands. That is the real test of a working system.
 
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Old 02-11-19, 04:39 AM
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@Airmark:

Very good explanation. This does bring up a manufacturing or design issue. Having the compressor try to push vapor is, of course, not reasonable. There should be a portion of the cooling loop and a portion of the hot loop that is joined just prior to the compressor input to guarantee that no vapor enters the compressor. This should be on T'd off legs and switched on if needed as sensors indicate.

With my electrical costs already very high, and the "Greens" wanting to push everyone's costs higher to cure a non existent problem in the atmosphere, you would think that energy efficiency would be a top priority. Constantly mixing hot & cold to solve a problem that may or may not exist wastes energy. Adding $50 worth of parts to a unit would save hundreds in operating costs over its life time.
 
 

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