Thread: Buried Refrigerant Line and Run Distance ?

I know this was discussed many moons ago, but I cannot locate the thread.

Today, I found a refrigerant line at a condensing unit that was at the rear of a home that was buried below the ground and ran approximately 60ft around the structure where it entered the brick veneer and across the attic to the air handler. We're talking 70-80ft. in distance.

The line did enter into some PVC material near the the condensing unit but where it came up from the ground no such protection was present.

Can the line be buried as such and for such a long distance. Seems as if it could reduce the efficiency of the equipment not counting the possibility of damages to the line being below the ground. This same side of the structure where the line is present is going to have extensive foundation repairs next week, so I can just see the damages coming to this line.

Any thoughts on this I'd would appreciate as always.

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Yup... guess who they'll call after the foundation repairs have been made and the unit is not functional...
(see photo for culprit)

Rich

Dang, that is one good looking ole boy. Hope he watches his step.

Seriously Richard, me and my son drove by that old house one day and thought we take some pics of it. Next thing I knew we had a ladder up against the roof as if we were going up on the thing. A few months ago someone sit that old house on fire. It was firestarter material for sure.

Originally Posted by Rick Hurst

Can the line be buried as such and for such a long distance.

Yes, they can.

I've seen some even further away.

I called an HVAC contractor I knew at the time and his response was 'Under the right design conditions, size of the refrigerant lines, manufacturers allowances for distances and height between the two units, it varies on many things - you'd need to look it all up in the book and check out what is there.'

I advised my client that 'it might have been designed within all the appropriate parameters, but I recommend having an HVAC contractor check it out and verify it is okay, that spending a hundred or so would provide the answer of *yes, it is okay* or *no, it is a problem*'.

I personally would not be too concerned. Its true that some small loss of efficiency or system capacity may be experienced due to the line set being buried. I would not expect that loss to be significant enough to lose much sleep over though.

The overall length of run of the refrigerant lines is a somewhat larger issue in my mind and might have called for an increase in the copper tubing diameter.

Check the manufactures' "long line" requirements, both horizontal and vertical separation have to be considered.

For example, here's Carrier's requirements for residential Puron units:

http://www.xpedio.carrier.com/idc/gr...t/llgp-2xa.pdf

I encouned the same situaion, the line buried under conrete but only about 15 feet. I'm going to report it as wrong. I don't believe that the line is meant to be buried unprotected, the copper may deteriorate faster.

Opinions?

Why do you think the copper will deteriorate rapidly? I have never seen this done with HVAC refrigerant lines, but most of the propane lines in this part of the country are copper. They serve well.

Thank you Darrel. I was told that it did, but I'm glad to hear that from you, my other source was not very trustworthy.

Originally Posted by Darrel Hood

Why do you think the copper will deteriorate rapidly? I have never seen this done with HVAC refrigerant lines, but most of the propane lines in this part of the country are copper. They serve well.

In my Hood the ground water is very low PH ~ high acidity, ( the foot hils / acid rain thing ). Fine for human consumption, but it slowly eats away at copper. If there's a well, it slowly eats up the copper above ground also.

In my area we have thousands of homes with copper water supply pipes that have been buried for years. I would have a very difficult time trying to sell the notion that buried copper pipe is going to deteriorate.

Thanks to all, actually here in San Diego copper is buried all the time, I don't know what I was thinking, I just have a bad feeling about the way this was done. (besides the insulation being damaged)

Originally Posted by Jack Feldmann

In my area we have thousands of homes with copper water supply pipes that have been buried for years. I would have a very difficult time trying to sell the notion that buried copper pipe is going to deteriorate.

Low PH water and resultant copper deteriation is not about code or legality. It just is. My home was built in 1990 and the copper water piping was replaced somewhere around 2000 because of deterioration. I've been here for eight years and have had three pinhole leaks. Helped my neighbor replace some of his copper water line, ( older home ), and the copper we took out was newspaper thin. It is not a universal problem, but it lives. Water acidic neutralizing and filtering systems are sold for this.

To add to the discussion.
Conditions Contributing to Underground Copper Corrosion

Originally Posted by Marzio Fernandez

I encouned the same situaion, the line buried under conrete but only about 15 feet. I'm going to report it as wrong. I don't believe that the line is meant to be buried unprotected, the copper may deteriorate faster.

Opinions?

Here in SoCal, any copper going through a concrete slab MUST be sleeved to prevent direct contact.

This can be done if done correctly. I have done it several times. The lines should be run inside PVC conduit with long sweep bends, they need to be over sized and the factory charge needs to be adjusted. Units come charged for about 25 ft of run. More than that requires more refrigerant be added.

Given the location and the pending foundation work, I think this would be a great time to check all that and repair as needed.

My largest concern is not that the line would deteriorate any faster (necessarily) but that the cool below grade pipe may pool the refrigerant oil when not in operation. ESPECIALLY when the entire length of the horizontal run is basically a trap. In other words if it drops below grade at the CU then travels horizontally below grade then rises back up, which if I read correctly is exactly what you have.

The compressor starts up and that pool of oil/refrigerant slugs the compressor.

Hi, I am a refrigeration tech. - Copper corrosion is NOT the main issue with the line sets buried underground.

In any AC or refrigeration system the refrigerant will migrate to the coldest part of the system and collect as a liquid when it is not running.

When this occurs and the system starts, this liquid is drawn into the compressor - this is refereed to as liquid slugging. Compressors are designed to pump vapor only and this will break valves, bend or snap connecting rods, etc.

Some manufacturers state in the IOM that 2 to 3 feet is OK and others state under no circumstance will they warranty the equipment if the lines are buried.

Picture connecting a fire hose to the air intake of the engine of your car, turning on the hose, then trying to start the engine....

-John

A suction accumulator is all that would be needed if liquid refrigerant in the buried line set did become a problem. Adding one would be a little bit of an added expense (if the unit is not already equipped with one) but it would keep the liquid refrigerant from getting into the compressor cylinders.

Originally Posted by Dana Bostick

Here in SoCal, any copper going through a concrete slab MUST be sleeved to prevent direct contact.

Ditto in British Columbia.

Originally Posted by Dana Bostick

Here in SoCal, any copper going through a concrete slab MUST be sleeved to prevent direct contact.

Originally Posted by Dale Trach

Ditto in British Columbia.

That may be because the code *requires* it to be sleeved.