Avoid gaps and missing insulation along the refrigeration lines
Proper placement and securing of insulation on air conditioner or heat pump refrigeration lines is important to avoid condensation leaks into the building. One, or on some systems both refrigeration lines can be cool or cold under some operating conditions.
The cold copper tubing in contact with warm humid air causes moisture in the air to condense onto and then drip off of the refrigration lines.
The result can be leaks into the building, as our photo at left illustrates.
Missing or damaged refrigerant line insulation insulation on the refrigerant lines, particularly on the larger suction line, will cause condensation and drips from the lines in humid areas.
In our photo at above left where refrigerant line insulation is incomplete, the drip stains on the attic floor may well indicate a point at which leak stains or even mold appear on the ceiling below.
In our photo at left none of the refrigerant lines are insulated where they emerge from the building wall. If the lines were also uninsulated within the wall, depending on their location and the wall's dew point properties, a condensation, leak, mold, rot, or insect problme can ensue.
We have seen very costly building damage where lines were not properly insulated indoors: condensate drips wet gypsum board walls, leading to a costly mold remediation project.
Missing refrigerant line insulation also may increase system operating cost or in addition to a condensation worry, uninsulated high pressure refrigerant lines may result in unwanted heat transmission into some building areas.
At left we illustrate a neat insulation job visible on the outdoor portion of refrigerant piping for a split system ductless air conditioner installlation.
According to McQuay International, a large producer of refrigeration equipment,
Suction lines are cold – 40°F (4.4°C) SST – and cause condensation, even in conditioned spaces. In addition, any heat that enters the refrigerant adds to the superheat and reduces system efficiency.
For these reasons, suction lines should be insulated with a vapor proof insulation. This is a requirement of many building codes. Rubratex is the most common form of refrigerant line insulation.
Liquid lines generally are insulated. They are warm to hot (110°F (43.3°C) for air-cooled). If liquid lines pass through a space that is warmer than the refrigerant (i.e. the roof of a building at roof level), or if they could be considered hot enough to pose a safety risk, then insulation should be added.
Discharge lines are generally uninsulated. They may be very hot, in excess of 150°F (66°C), so insulation may be warranted as a safety consideration, or if the heat loss from the discharge gas line would be considered objectionable to the space.
Hot gas bypass lines should be insulated, especially if the runs are long or if the piping is exposed to cold temperatures.
Do Not Compress Insulation on A/C or Heat Pump Refrigeration Lines
But he made the same mistake on the insulation on the refrigeration lines and condensate drain where they extend outdoors between the building wall and the compressor/condenser unit.
Our photographs illustrate that the importance of not compressing refrigeration line insulation is no joke. In our photo at below left, notice those drip stains below the condensate lines at each location where the insulation was compressed by a too-tight plastic tie?
And in the two photos at below right, notice the incomplete insulation on the refrigeration line? It leaves me worried about condensation and water accumulation inside the wall cavity as well. Since I know this installer is not stupid we're left thinking he has a bit of contempt for his customers, or a limited concept of workmanship.
Imagine that same dripping and accumulation of water where the installer made the same mistake in a fiberglass-batt insulated wall or a wall or ceiling inside which the dew point may be reached on the refrigeration lines? The accumulation of water in a building cavity is asking for a costly mold, insect, or rot damage problem later on.
Missing insulation on the refrigeration lines outdoors is not a catastrophe - at least for a short un such as at this split system compressor/condenser unit. Perhaps a little loss in efficiency of the system operation in some weather conditions. On a long refrigeration line run, say between an attic air handler and a ground level compressor/condenser, the effects may be more significant.
We removed the leaky, incomplete, and ugly squashed insulation on the refrigeration lines for this system (above left), replacing the squashed foam insulating tubing with new insulation (above right).
Incidentally, just clipping off the old plastic wire ties to "release" the squashed refrigerant line foam insulation won't work: after a few months the insulating foam remains permanently squashed, as you can see in our photo at left.
The manufaturer (Sanyo) recommends covering the foam insulation on the refrigeration line with weatherproof tape which we did at the end of this job.
I admit that we "over-designed" the final insulation job shown in our last photo with that extra layer of foam that surrounds both lines, as we used more thickness of insulation than necessary.
We did so to end with a neat, weather-protected job that, combined with the application of black weatherproof tape, should last for a long time.
Notice that the aluminum or plastic ties used to hold components in place were left loose - we did not squash the new refrigerant line insulation, and we made sure it was continuous, neat, and protected from the weather.
A neat installation takes what, maybe five minutes longer than a sloppy one, but it took about an hour to buy the replacement refrigerant line insulation, remove the original sloppy installation, and do the job right the second time.
Protect outdoor refrigerant line insulation from the weather
Manufacturers also recommend wrapping the insulated refrigerant lines exposed to outdoor weather, using an appropriate weatherproof tape.
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