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Old 09-07-2012, 05:07 PM   #1
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Sweating return line


My attic is semi-conditioned.My heat pump air handler is in attic. In cooling mode the uninsulated return line sweats and drips a little in attic. Would it hurt to insulate the uninsulated line that is in the attic .The other half of lineset is outside going down the wall. I assume it is uninsulated for a reason and I don'nt want to hurt perfomance, because it works great. Joe in North Ga

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Old 09-07-2012, 07:38 PM   #2
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Sweating return line


Return duct or return refrigerant line? Either way, insulate it.

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Old 09-07-2012, 08:02 PM   #3
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Insulate it.
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Old 09-07-2012, 09:00 PM   #4
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I assume it is uninsulated for a reason



The reason being the installer was too lazy to insulate it.
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Old 09-07-2012, 09:08 PM   #5
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Sweating return line


Insulate the suction line which is the return line
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Old 09-08-2012, 06:43 AM   #6
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Sweating return line


The line that is sweating is the ininsulated refrigerant line (on the lineset) not duct. I have never seen a heatpump lineset for a house that both lines on lineset were insulated only one. It only sweats in the insulated attic and in cooling mode. Not outside where it goes down the outside side of the house. So my question is .Can you insulate both sides of a lineset on a heatpump lineset and would it effect performance. Thanks for the replies.
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Old 09-08-2012, 07:10 AM   #7
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Sweating return line


[quote=Joe Boulware;1005412]The line that is sweating is the ininsulated refrigerant line (on the lineset) not duct. I have never seen a heatpump lineset for a house that both lines on lineset were insulated only one. It only sweats in the insulated attic and in cooling mode. Not outside where it goes down the outside side of the house. So my question is .Can you insulate both sides of a lineset on a heatpump lineset and would it effect performance. Thanks for the replies. July of 2010 I had Isonene sprayed in my attic under the roofing and it is now unvented . My power usage has been cut in half summer and winter compared to the previous 18 years . So far this sweating deal has been the only other change up there.
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Old 09-08-2012, 07:23 AM   #8
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Sweating return line


Since you reduced the cooling load, the line is getting colder then it use to. The vapor line should always be insulated to prevent condensation.
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Old 09-08-2012, 07:27 AM   #9
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Sweating return line


Both lines can be insulated with no ill effects to your system. The big line,suction , should have been insulated already. The liquid line,small one, should be a few degrees warmer than the outside air temp. If the small line is cool enough to condensate then you have a refrigerant problem.

Last edited by Marty S.; 09-08-2012 at 07:29 AM.
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Old 09-08-2012, 07:27 AM   #10
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http://www.hvacfun.com/a-understandi...rig-piping.htm

Piping Insulation

All piping joints and fittings should be thoroughly leak tested before insulation is sealed. Suction lines should be insulated to prevent sweating and heat gain. Insulation covering lines on which moisture can condense or lines subjected to outside conditions must be vapor sealed to prevent any moisture travel through the insulation or condensation in the insulation.

Although the liquid line ordinarily doesn't require insulation, the suction and liquid lines can be insulated where the two lines are clamped together. When it passes through an area of higher temperature, the liquid line should be insulated to minimize heat gain. Hot gas discharge lines usually are not insulated; however, they should be if the heat dissipated is objectionable or to prevent injury from high-temperature surfaces.
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Old 09-08-2012, 07:34 AM   #11
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Sweating return line


On a heat pump, the vapor line becomes the hot gas discharge line in heat mode. And it should be insulated so it doesn't lose too many BTUs to the ambient air, and cost you more to heat your house.
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Old 09-08-2012, 05:01 PM   #12
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Sweating return line


Yes ur right Marty..if the refrigerant line is sweating that means that there is a problem with the pressures u should have a a/c tech come out an do a routine maintaince to be safe
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Old 09-08-2012, 07:27 PM   #13
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Yes ur right Marty..if the refrigerant line is sweating that means that there is a problem with the pressures u should have a a/c tech come out an do a routine maintaince to be safe

It is not uncommon for an uninsulated low pressure line to sweat in an unconditioned space...especially in an attic.

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