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Is it OK to bury refrigerant lines?


Steven Hockstein
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I inspected a house this past week and the air conditioning compressor is located in the rear yard. The electrical supply and the refrigerant lines are buried in the ground. The furnace is in a utility closet that is accessed from an exterior door at the rear of the house.

Refrigerant pipe issues: Is it OK to bury the refrigerant lines and is the standard insulation wrap acceptable when buried. If not, what has to be done?

Electrical issue: The compressor is about 25 feet from the house and the electric shut-off is on the house, not on the enclosure adjacent to the A/C compressor. Is this allowed (the shut-off can be seen from the compressor).

Opinions please?

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I inspected a house this past week and the air conditioning compressor is located in the rear yard. The electrical supply and the refrigerant lines are buried in the ground. The furnace is in a utility closet that is accessed from an exterior door at the rear of the house.

Refrigerant pipe issues: Is it OK to bury the refrigerant lines and is the standard insulation wrap acceptable when buried. If not, what has to be done?

I've seen it done that way several times and I've never considered it to be a problem. I'm not aware of any rule against it.

Electrical issue: The compressor is about 25 feet from the house and the electric shut-off is on the house, not on the enclosure adjacent to the A/C compressor. Is this allowed (the shut-off can be seen from the compressor).

Opinions please?

If the disconnect is within sight and within 50' of the compressor, it's fine.

- Jim Katen, Oregon

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I inspected a house this past week and the air conditioning compressor is located in the rear yard. The electrical supply and the refrigerant lines are buried in the ground. The furnace is in a utility closet that is accessed from an exterior door at the rear of the house.

Refrigerant pipe issues: Is it OK to bury the refrigerant lines and is the standard insulation wrap acceptable when buried. If not, what has to be done?

I've seen it done that way several times and I've never considered it to be a problem. I'm not aware of any rule against it.

Electrical issue: The compressor is about 25 feet from the house and the electric shut-off is on the house, not on the enclosure adjacent to the A/C compressor. Is this allowed (the shut-off can be seen from the compressor).

Opinions please?

If the disconnect is within sight and within 50' of the compressor, it's fine.

- Jim Katen, Oregon

Thanks. I have never seen a system installed this way. I felt it was OK but was not sure.

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So it's ok for the high pressure(hot) line to be burried in the cool ground? Could this have a bad effect?

Perfectly fine, in fact you could pick up a little subcooling if the ground is below the air temperature. A heat pump would need both lines insulated.

A few years ago, I researched a HP that had the ground source copper coil buried.

I don't know if the system is still around though. If copper water lines can be buried, I don't see any problem.

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Here is Trane's opion on underground linesets.

Underground refrigerant line sets

Stay away from under ground refrigerant line sets when

possible. This design will create two situations:

The world’s longest oil trap

A vapor line that acts as a liquid receiver

Liquid refrigerant will always migrate to the coldest spot in

a system; this will likely be the line sets under ground.

A vapor line full of liquid refrigerant will slug the

compressor on start up—especially during long off cycles.

The addition of a liquid line solenoid valve (cooling only

units) will reduce the migration of liquid refrigerant and

help save the life of the compressor.

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Here is Trane's opion on underground linesets.

Underground refrigerant line sets

Stay away from under ground refrigerant line sets when

possible. This design will create two situations:

The world’s longest oil trap

A vapor line that acts as a liquid receiver

Liquid refrigerant will always migrate to the coldest spot in

a system; this will likely be the line sets under ground.

A vapor line full of liquid refrigerant will slug the

compressor on start up—especially during long off cycles.

The addition of a liquid line solenoid valve (cooling only

units) will reduce the migration of liquid refrigerant and

help save the life of the compressor.

When line sets are buried they are typically close to the surface, not five feet down (who in the hell goes through all that work?)

A liquid line solenoid valve will only help the condition when the unit has a pump down cycle - something that 99% of residential units do not have. A suction line accumulator will help prevent a slug of liquid coming back to the compressor - another option that most residential units do not have (my EMI ductless split system has one though). As far as the world longest oil trap goes I would be doubtful of that. Is the condensing unit 200 feet from the home? While oil does migrate through out the system more likely is a liquid slug than a pocket of oil (that is unless the evaporator is located stories above or below the condensing unit).

Should the client freak out and demand that the line set be dug up and run along the surface - no. We typically have bigger fish to fry.

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