buried suction/liquid lines

[bovast]

Hi

Does anybody see any reason, other than protection from physical damage, that buried linesets need to be inside conduit. Is this required by code?

[MB1211]

Why? Is burying them in conduit a problem? In my opinion, it's the correct way to have it done.

[bovast]

not wondering what is best, I agree with you, but I am wondering what the reason is for conduit so I can be better informed

[MB1211]

I like to insulate both lines inside the conduit to prevent rubbing. Around here there are alot of rocks and the conduit provides protection for the insulation from being crushed, nicked and then the copper nicked and potentially leak. I ever remember seeing anything in a code book about having to be in conduit but the key word is protected so yes it should be in conduit.

[bovast]

okay, so other than physical damage there is no other reason? This is what I suspected. But wanted to be sure. I was told it had to do with corrosion and this confused me. Copper water lines are direct buried all the time. Thanks for your input.

[MB1211]

No problem. Corrosion? Well maybe, but how acidic is the soil? There are plenty of copper water lines around here and they usually break because of rocks or tree roots. Vibration is my biggest worry. Good luck.

[bovast]

Soil is very alkaline (AZ). I was told by a building inspector "Make sure you put your lineset in conduit if you bury it" I thought to myself "yeah of course" but when I mentioned that it would probably be okay in my sandy soil, he started to feed me what I suspected was B.S. but I don't argue with people who appear to know more than me.

[bovast]

oh yeah, and he said iI need to seal both ends to keep out moisture??? Isn't that to keep out dirt and rocks?

[OregonYeti]

Once when i installed a heat pump outdoor unit, the line set had been roughed in and terminated right about at ground level (yeah thanks whoever did that). It went down from there. The ends had been taped off. When I pulled a vacuum it took over 2 hours to get down to 500 microns, and this was on a hot day. I bet a lot of water had gotten into the line set.

[Shophound]

oh yeah, and he said iI need to seal both ends to keep out moisture??? Isn't that to keep out dirt and rocks?

The suction line, although insulated, will be considerably colder than its surroundings. The insulation will slow down heat transfer from the surrounding air and conduit material but not stop it. Therefore, if the ends of the conduit are open to the atmosphere and moisture from air is allowed to enter, somewhere in that conduit it will sooner or later condense...even ground temperature can do it if normal ground temperature is low enough and entering air has a relatively high dew point.

Rain is another factor...you don't want water sitting in this conduit tube, ever. If you ever have a refrigerant leak in the system (let's say other than in the tube) and, with the compressor running, the suction side goes into a vacuum, you could pull an awful lot of moisture into the system and kill the compressor in the process.

There are likely other reasons as well but these two I thought of first.

[Airmechanical]

Soil is very alkaline (AZ). I was told by a building inspector "Make sure you put your lineset in conduit if you bury it" I thought to myself "yeah of course" but when I mentioned that it would probably be okay in my sandy soil, he started to feed me what I suspected was B.S. but I don't argue with people who appear to know more than me.


your correct he does know more than you! :(



.

[heatpumpguru]

I have seen in install books,due to oil migration issuses you should not bury linesets.

[bltinnc]

put it in dwv with long bends so you could get it out in the future if you wanted to increase the size, i've put uf in conduit just for saftey sake especially where it enters the ground and leaves

[MB1211]

I don't personally like the idea of burying linesets but if there is no other alternative it has to be done correctly. All the points brought up here should be considered and used in my opinion. Long turn 90 on ends, insulate both lines, seal both ends etc. I have only ever buried one lineset over the years and that one was last year. Condensor location was the low point. The linset was just under the patio so there was no fear of trapping oil. What can be learned from all of this? It really depends on a lot of little factors and should only be buried as a last resort IMHO.

[hvac_superman]

How about freezing. If water gets into the conduit and then freezes, It could possibly crush the copper tube.

[MB1211]

I guess it really depends where you are and your climate.

[docholiday]

Dont bury it, no matter what you do, it will be a potential issue. The problem is that the ground is a greater heat sink than the air. When you put something in the ground you pull heat from it (or add heat to it) much faster than you do the air. In the off cycle, the refrigerant will migrate to that coldest point and on start up, you just slugged the crap out of your compressor.

Also as mentioned, if you use a conduit and water forms, you end up with the same problem so the conduit was a waste of time.

If you have no olternative, then make sure the conduit is sealed at the top and has good drainage toward and into the house. In the long run, it's just not a good idea.